| the shivering pattern in an arctic (willow ptarmigan) and a tropical bird (bantam hen). | | 1976 | 3318 |
| the occurrence of gapeworm (syngamus trachea) in willow grouse. | 21.4% of the willow grouse (lagopus lagopus) examined from a coastal locality in northern norway were infected with syngamus trachea. none of the willow grouse examined from an inland locality with colder and longer winters were infected with the parasite. it is suggested that the parasite may influence survival of the grouse population. | 1975 | 124787 |
| studies of louping-ill virus (flavivirus group) in wild red grouse (lagopus lagopus scoticus). | studies were made to find evidence of louping-ill virus infection in free-living red grouse and relate this to their breeding success. in areas where ticks were abundant 61 (84%) adult grouse had antibody to the virus compared with 1 (10%) in areas where ticks were relatively scarce. of 162 chicks tested 25 were shown to be viraemic. infected chicks were of significantly less weight than comparably aged uninfected birds and the probability that they died was much greater than that of uninfected ... | 1978 | 212479 |
| atrophy of a breast muscle with a single fibre type (m. pectoralis) in fasting willow grouse, lagopus lagopus (l.). | the willow grouse (lagopus lagopus) are arctic gallinaceous birds with small fat stores and large muscles. in winter, these birds may starve for periods of several days. it was important to know which energy reserves were utlized during periods of starvation. body composition of female willow grouse and bantam hens was studied before and after fasting. grouse have much larger breast muscles than do bantams, but reproductive organs are larger in hens. the relative amounts of adipose tissue are ab ... | 1978 | 681910 |
| haematology, weight and condition of captive red grouse (lagopus lagopus scoticus) infected with caecal threadworm (trichostrongylus tenuis). | red grouse infected with the caecal threadworm trichostrongylus tenuis developed a mild anaemia. haemoglobin and albumin levels in the blood fell but there were no significant changes in the number of red blood cells or their size. in infected birds the numbers of circulating eosinophils and heterophils increase, as did the concentration of alpha, beta and gamma globulin. body weights did not change but muscle masses shrank. birds that subsequently died had the lowest concentration of haemoglobi ... | 1978 | 749086 |
| listeriosis among willow grouse (lagopus lagopus) in captivity. | | 1975 | 803676 |
| the effects of castration on concentrations of luteinizing hormone in the plasma of photorefractory red grouse (lagopus lagopus scoticus). | | 1977 | 892416 |
| multilocus dna fingerprints in gallinaceous birds: general approach and problems. | multilocus profiles were investigated in five different species of galliformes (ring-necked pheasant phasianus colchicus, indian peafowl pavo cristatus, japanese quail coturnix coturnix japonica, domestic chicken gallus gallus, and red grouse lagopus lagopus scoticus) using two human multilocus probes (33.6 and 33.15) in combination with each of four restriction enzymes (alui, ddei, haeiii or hinfi). all the species show a dna fingerprint-like pattern using at least one restriction enzyme in com ... | 1992 | 1612925 |
| factors affecting the establishment of the caecal threadworm trichostrongylus tenuis in red grouse (lagopus lagopus scoticus). | the resistance of captive reared red grouse to trichostrongylus tenuis was measured as the proportion of ingested infective 3rd-stage larvae which failed to develop to adult worms. individual grouse showed wide, repeatable variations in resistance. seasonal variations may also have occurred. red grouse acquired little or no effective immunity to reinfection after challenge with a single dose of infective larvae. in trickle-dosed grouse, however, adult worms weakly inhibited the establishment of ... | 1989 | 2594417 |
| development and survival of the free-living stages of trichostrongylus tenuis, a caecal parasite of red grouse lagopus lagopus scoticus. | in the laboratory, yields of infective 3rd-stage larvae of trichostrongylus tenuis were determined by temperature when moisture was adequate. on the moor, eggs in caecal faeces did not develop to infective larvae during the winter. in summer, development did occur and yields of infective larvae were related to temperature: greatest yields were obtained when mean monthly soil surface temperatures ranged between 7.6 and 10.3 degrees c. rainfall was unimportant, as was desiccation. during summer th ... | 1989 | 2797866 |
| arrested development of trichostrongylus tenuis as third stage larvae in red grouse. | worms were counted in red grouse (lagopus lagopus scoticus) in north east scotland in march, april, august, september, november and december 1986. immature worms occurred as third (l3) and fourth (l4) stage larvae throughout. two kinds of evidence suggest that l3 larvae spent much of the winter in a state of arrested development. first, recently acquired l3 larvae could be distinguished by the fact that they retained outer l2 cuticles for a few days; these were present only in the august and sep ... | 1988 | 3194598 |
| regulation and grinding ability of grit in the gizzard of norwegian willow ptarmigan (lagopus lagopus). | fluctuations in grit composition in the gizzards of willow ptarmigans and the grinding ability of various grit assortments from wild ptarmigans were examined. we confirmed reports of other investigators that larger, fewer and rounder stones were present in the winter than in the autumn. experiments showed that ptarmigans prefer stones with diameters between 2-5 mm. birds on a constant diet maintained a constant stone intake throughout the year. the composition of gizzard grit was influenced by t ... | 1975 | 1228713 |
| thermoregulatory behavior and body temperature in chicks of willow grouse (lagopus lagopus lagopus). | clocal temperatures (tcl) of outdoor living captive willow grouse chicks (lagopus lagopus lagopus) were found to increase from 39.4 +/- 0.5 degrees c. the first day to 40.3 +/- 0.5 degrees c. the twelfth day after hatching. average tcl of adults was 40.7 +/- 0.3 degrees c. when left alone for 30 min. in a controlled test environment providing temperatures ranging from 21 degrees c. to 46 degrees c., the one day old chicks preferred significantly higher ambient temperatures than eight day old bir ... | 1975 | 1161703 |
| proceedings: seasonal variations in plasma luteinizing hormone levels in male red grouse (lagopus lagopus scoticus). | | 1975 | 1133531 |
| endocrine changes in photostimulated willow ptarmigan (lagopus lagopus lagopus) and svalbard ptarmigan (lagopus mutus hyperboreus). | changes in plasma luteinizing hormone (lh), testosterone, thyroxine (t4), and triiodothyronine (t3) and the height of supraorbital combs were compared in captive willow ptarmigan (lagopus lagopus lagopus) and svalbard ptarmigan (lagopus mutus hyperboreus) exposed to an artificial annual cycle of daylength simulating that at 70 degrees n. plasma lh and testosterone and comb height increased more slowly in svalbard than in willow ptarmigan as daylength increased. in both species, plasma lh and tes ... | 1988 | 3371650 |
| the effect of trichostrongylus tenuis on the caecal mucosa of young, old and anthelmintic-treated wild red grouse, lagopus lagopus scoticus. | the caecal mucosa of wild young and adult grouse infected naturally with trichostrongylus tenuis was examined by means of scanning electron microscopy and compared with adult grouse which had been treated with an anthelmintic. the caecal mucosa of young red grouse with low worm burdens possessed longitudinal plicae and exhibited little damage. the caeca from adult grouse, most of which carried high worm burdens, showed a localized depression of plicae and atrophy and cell disruption in areas of ... | 1987 | 3588017 |
| changes in aromatase activity in the neuroendocrine tissues of red grouse (lagopus lagopus scoticus) in relation to the development of long-day refractoriness. | changes in aromatase activity in the neuroendocrine tissues of captive male and female red grouse (lagopus lagopus scoticus) were measured during a photo-induced breeding cycle. the gonads enlarged and subsequently regressed, as a consequence of the development of long-day refractoriness, within 84 days of transferring photoinsensitive birds from a non-stimulatory to a stimulatory daylength. the object of the study was to determine whether long-day refractoriness is related to an increase in aro ... | 1986 | 3944533 |
| the influence of ascorbic acid on the occurrence of tibial dyschondroplasia in young broiler chickens. | two distinctly different basal diets were used to test the influence of supplementary ascorbic acid on the occurrence of tibial dyschondroplasia. addition of either .1 or .25% ascorbic acid to these diets did not alter the occurrence of tibial dyschondroplasia in 25-day-old broiler chickens. however, supplementary ascorbic acid did increase the amounts of ascorbic acid present in blood plasma. also, individual differences in circulating ascorbic acid were not associated with this disease. furthe ... | 1985 | 4011557 |
| clostridium perfringens type a toxins in relation to nephritis and uric acid diathesis in captive willow ptarmigan (lagopus l. lagopus). | | 1982 | 6295118 |
| yersinia pseudotuberculosis infection in captive black grouse (tetrao lyrurus) and willow ptarmigan (lagopus l. lagopus). | | 1982 | 6762820 |
| orienting and freezing responses in incubating ptarmigan hens. | behavior studies and telemetric recordings of heart and respiration rates were performed on five wild and two captive, incubating, willow ptarmigan hens (lagopus lagopus lagopus) and on four wild, incubating, svalbard ptarmigan hens (lagopus mutus hyperboreus). sounds and sight of approaching humans, egg predators, or dogs near the nests elicited behavior in the hens which we have interpreted as an orienting response (or) followed by freezing behavior. during both types of behavioral responses, ... | 1985 | 4059382 |
| the digestion of heather (calluna vulgaris) by red grouse (lagopus lagopus scoticus). | | 1972 | 5015248 |
| annual cycle of plasma concentrations of growth hormone in red grouse (lagopus lagopus scoticus). | | 1982 | 7152243 |
| on caecal synthesis and absorption of amino acids and their importance for nitrogen recycling in willow ptarmigan (lagopus lagopus lagopus). | the willow ptarmigan has two large caeca housing dense populations of microorganisms. urine, containing uric acid, is transported from the cloaca into the caeca when these are filled. here the uric acid is rapidly broken down, suggesting that the caeca take part in a recycling of excretory nitrogen. in this work it is shown that ammonia produced by the uric acid decomposition is incorporated into new amino acids in a glutamic dehydrogenase catalyzed reaction. we have, however, not been able to d ... | 1981 | 7348031 |
| host specificity of trichostrongylus tenuis from red grouse and northern bobwhites in experimental infections of northern bobwhites. | the red grouse (lagopus lagopus scoticus) and northern bobwhite (colinus virginianus) are parasitized by the cecal nematode, trichostrongylus tenuis. our objective was to determine if t. tenuis from red grouse is infective in bobwhites. we inoculated bobwhites with infective-stage t. tenuis larvae that originated from red grouse in northern england and bobwhites in florida. we also inoculated domestic chickens with larvae from the same sources. none of the 6 bobwhites inoculated with larvae from ... | 1993 | 8331474 |
| caecal threadworms trichostrongylus tenuis in red grouse lagopus lagopus scoticus: effects of weather and host density upon estimated worm burdens. | trichostrongylus tenuis eggs were counted in faeces from individually marked wild red grouse for 8 years. egg counts varied seasonally and annually. in some years, a sudden increase in mid-april was consistent with delayed maturation of larvae which had overwintered in the birds in a hypobiotic state. a more gradual increase in summer was probably due to uninterrupted maturation of larvae ingested then. despite 30-fold year-to-year variation in mean egg counts, relative differences in egg counts ... | 1993 | 8414674 |
| hypobiosis of trichostrongylus tenuis in experimentally infected grey partridges. | storage of infective larvae (l3) of trichostrongylus tenuis at +4 degrees c for six weeks before being given as single infections to grey partridges (perdix perdix) did not increase the proportion of worms subsequently found to be hypobiotic. however, after repeated infections, hypobiotic larvae were numerous. three infections given over three weeks resulted not only in the presence of many hypobiotic larvae, but also in the coincident loss of most adult worms. this indication of the role of imm ... | 1993 | 8460270 |
| the effect of parasites on wildlife. | populations of animals which live in the wild are regulated by many biotic and abiotic factors. parasites are one of the biotic factors. parasites may influence their hosts in different ways. they may cause the death of the host due to a direct lethal effect or an indirect effect. direct lethal effects may occur if killing is a part of the life cycle of the parasite or if hosts and parasites have not developed an equilibrium. the introduction of hosts or parasites into a new environment with sui ... | 1996 | 8933697 |
| isolation and characterization of hypervariable microsatellites in the red grouse lagopus lagopus scoticus. | | 1997 | 9004522 |
| transmission dynamics and host-parasite interactions of trichostrongylus tenuis in red grouse (lagopus lagopus scoticus). | two components of the transmission dynamics of trichostrongylus tenuis in red grouse are examined and quantified, namely parasite transmission rate and density-dependent reductions in egg production. age-intensity data for birds of known age suggest that the rate of parasite uptake increases during the first 6 mo of a bird's life and this increase reflects an increase in feeding rate with age and exhibits no signs of self-cure. analysis of these age-intensity curves permits us to estimate the tr ... | 1997 | 9105295 |
| efficacy of acaricidal tags and pour-on as prophylaxis against ticks and louping-ill in red grouse. | this paper examines the efficacy of 10% lambdacyhalothrin-impregnated plastic tags and a deltamethrin pour-on preparation in protecting red grouse chicks from parasitism by ticks and subsequent infection with the louping-ill virus. in 1995, ten red grouse hens (lagopus lagopus scoticus) in a free-living population in north-east scotland were fitted with lambdacyhalothrin-impregnated plastic tags, glued to radio transmitters. chicks of more than 10 days of age from a further ten untreated radio-c ... | 1997 | 9430120 |
| a comparison of the responses of captive willow ptarmigan (lagopus lagopus lagopus), red grouse (lagopus lagopus scoticus), and hybrids to increasing daylengths with observations on the modifying effects of nutrition and crowding in red grouse. | | 1981 | 7286635 |
| the response of three grouse species (tetrao urogallus, lagopus mutus, lagopus lagopus) to louping-ill virus. | | 1980 | 6253539 |
| local genetic structure in red grouse (lagopus lagopus scoticus): evidence from microsatellite dna markers. | allelic variation at seven hypervariable tri- and tetranucleotide microsatellite loci was used to determine levels of population differentiation between 14 populations of red grouse (lagopus lagopus scoticus) in northeast scotland, uk. despite the potential for long-distance dispersal in grouse, and a semicontinuous habitat, significant population divergence was observed (mean rst = 0.153; p < 0.01) and an isolation-by-distance effect detected (mantel test: p < 0.001). examination of the spatial ... | 1998 | 9859199 |
| development of photorefractoriness in willow ptarmigan (lagopus lagopus lagopus) and red grouse (lagopus lagopus scoticus) exposed to different photoperiods. | | 1982 | 7067969 |
| the epidemiology of louping-ill, a tick borne infection of red grouse (lagopus lagopus scoticus). | the epidemiology of louping-ill in red grouse was studied in northern britain concentrating on the possible role of other species and mechanisms of disease persistence. this tick borne viral disease caused heavy mortality in red grouse, particularly chicks. louping-ill induced mortality reduced the strength of the density dependence that generates the tendency of grouse populations to cycle and in some populations may cause population sinks. four routes of transmission were examined and non-vira ... | 1997 | 9802086 |
| matrilineal genetic structure and female-mediated gene flow in red grouse (lagopus lagopus scoticus): an analysis using mitochondrial dna. | dna sequence variation at the hypervariable 5' end of the mitochondrial control region was examined in 247 individuals to detect genetic divergence among 14 populations of red grouse (lagopus lagopus scoticus) in northeastern scotland. ten haplotypes were resolved, several of which were shared among populations. analysis of molecular variance, nei's gamma st, and a cladistic estimate of the amount of gene flow indicated a lack of overall population differentiation. patterns of overall panmixia a ... | 2000 | 10937204 |
| vitamin c deficiency in growing willow ptarmigan (lagopus lagopus lagopus). | willow ptarmigan chicks raised on a diet containing 265 mg ascorbic acid/kg develop scury-like symptoms and die by 4 weeks of age. if blueberry plants are given as an ad libitum supplement to this diet, the malady is prevented. we have described the clinical, pathological and histological changes which accompany this malnutrition and conclude that they are in accord with the description of scurvy in guinea pig and man. biochemical determination of ascorbic acid synthesis in the kidney of ptarmig ... | 1979 | 512712 |
| role of small mammals in the persistence of louping-ill virus: field survey and tick co-feeding studies. | louping-ill (li) is a tick-borne viral disease of red grouse, lagopus lagopus scoticus lath. (tetraonidae: galliformes), and sheep, ovis aries l. (bovidae: artiodactyla), that causes economic loss to upland farms and sporting estates. unvaccinated sheep, grouse and mountain hares, lepus timidus l. (leporidae: lagomorpha), are known to transmit li virus, whereas red deer, cenrus elaphus l. (cervidae: artiodactyla), and rabbits, oryctolagus cuniculus l. (leporidae: lagomorpha), do not. however, th ... | 2000 | 11016435 |
| analysis of aggregation, a worked example: numbers of ticks on red grouse chicks. | the statistical aggregation of parasites among hosts is often described empirically by the negative binomial (poisson-gamma) distribution. alternatively, the poisson-lognormal model can be used. this has the advantage that it can be fitted as a generalized linear mixed model, thereby quantifying the sources of aggregation in terms of both fixed and random effects. we give a worked example, assigning aggregation in the distribution of sheep ticks ixodes ricinus on red grouse lagopus lagopus scoti ... | 2001 | 11393830 |
| evolution of the mitochondrial dna cytochrome b gene in tetraonidae birds]. | mitochondrial fragments containing the cytochrome b gene (1020 bp in size) of four bird species belonging to four genera of the family tetraonidae (tetrao parvirostris, bonasa umbellus, lagopus lagopus scoticus, and falcipennis falcipennis) were directly sequenced. of the 1020 nucleotide positions, 186 were variable and uniformly distributed over the gene and only 46 were parsimony informative. most substitutions were synonymous. replacement substitutions were detected for 15 out of 340 amino ac ... | 2000 | 10994496 |
| platinum group elements in the feathers of raptors and their prey. | platinum (pt), palladium (pd), and rhodium (rh) concentrations were determined in the feathers of three raptor species in sweden, the sparrowhawk ( accipiter nisus), the peregrine falcon ( falco peregrinus), and the gyrfalcon ( falco rusticolus), as well as the main prey of the sparrowhawk (the house sparrow, passer domesticus) and the gyrfalcon (the willow grouse, lagopus lagopus). the analysis of feathers from 1917-1999 revealed a clear temporal trend, with significantly higher rh concentratio ... | 2002 | 11910463 |
| cestodiasis in the red grouse in scotland. | little is known about the cestode parasites of red grouse lagopus lagopus scoticus. the carcasses of 71 free-living and grouse collected from northeastern scotland (uk) between june 1991 and september 1992 were examined for the cestode paroniella urogalli. over 70% of young and old birds were infected in summer and winter. cestode abundance ranged from 0 to 29 (mean +/- se = 5.54 +/- 0.81) worms per host and did not differ significantly between young and old grouse, or between seasons. cestode i ... | 1999 | 10231751 |
| habitat loss and raptor predation: disentangling long- and short-term causes of red grouse declines. | the number of red grouse (lagopus lagopus scoticus) shot in the uk has declined by 50% during the 20th century this decline has coincided with reductions in the area of suitable habitat and recoveries in the populations of some avian predators. here we use long-term records of shooting bags and a large-scale manipulation of raptor density to disentangle the effects of habitat loss and raptor predation on grouse populations. the numbers of grouse harvested on the eskdale half of langholm moor in ... | 2000 | 10821608 |
| the role of non-viraemic transmission on the persistence and dynamics of a tick borne virus--louping ill in red grouse ( lagopus lagopus scoticus) and mountain hares ( lepus timidus). | there exist many tick borne infections that are of either economic or public health interest. mathematical models have previously been used to describe the dynamics of these infections. however it has recently come to light that there is an alternative mechanism for the transmission of these diseases that has not been considered in a modelling framework. this is transmission through ticks co-feeding on non-viraemic hosts. this paper extends a simple mathematical model to include this alternative ... | 2004 | 14745507 |
| the effect of aggressiveness on the population dynamics of a territorial bird. | a central issue in ecology lies in identifying the importance of resources, natural enemies and behaviour in the regulation of animal populations. much of the debate on this subject has focused on animals that show cyclic fluctuations in abundance. however, there is still disagreement about the role of extrinsic (food, parasites or predators) and intrinsic (behaviour) factors in causing cycles. recent studies have examined the impact of natural enemies, although spatial patterns resulting from r ... | 2003 | 12610624 |
| generation of periodic waves by landscape features in cyclic predator-prey systems. | the vast majority of models for spatial dynamics of natural populations assume a homogeneous physical environment. however, in practice, dispersing organisms may encounter landscape features that significantly inhibit their movement. we use mathematical modelling to investigate the effect of such landscape features on cyclic predator-prey populations. we show that when appropriate boundary conditions are applied at the edge of the obstacle, a pattern of periodic travelling waves develops, moving ... | 2002 | 11886619 |
| weak compensation of harvest despite strong density-dependent growth in willow ptarmigan. | ptarmigan and grouse species (lagopus spp.) are thought to be able to compensate for a modest harvest because there is a surplus of breeding birds that are prevented from breeding by territory holders. to estimate the degree of harvest-mortality compensation reliably we experimentally harvested 0%, 15% and 30% of the willow ptarmigan (lagopus lagopus) on 13 estates ranging from 20 to 54 km2 in size during four hunting seasons in norway according to a regional block design. population overwinter ... | 2004 | 15101697 |
| standard sampling techniques underestimate prevalence of avian hematozoa in willow ptarmigan (lagopus lagopus). | a total of 68 willow ptarmigan (lagopus lagopus l.) was collected during september 1995 from two localities in troms county, northern norway. thin blood smears were prepared and examined for blood parasites. of the 68 willow ptarmigan examined, 94% harbored one or more species of hematozoa. there were four (6%), 44 (65%), 16 (24%), and four (6%) birds infected by zero, one, two, and three species of parasites, respectively. prevalences at the coastal locality, kattfjord (n = 43), were leucocytoz ... | 2003 | 12910763 |
| faecal egg counts provide a reliable measure of trichostrongylus tenuis intensities in free-living red grouse lagopus lagopus scoticus. | the reliability of different egg counting methods for estimating the intensity of trichostrongylus tenuis infections in red grouse, lagopus lagopus scoticus, was investigated in the autumn, when grouse may harbour high parasite intensities. possible limitations to the use of these methods were also examined. faecal egg counts were found to accurately estimate t. tenuis worm intensities, at least up to an observed maximum of c. 8000 worms. two egg counting methods (smear and mcmaster) gave consis ... | 2004 | 14972040 |
| population biology of trichostrongylus tenuis, a parasite of economic importance for red grouse management. | the caecal nematode, trichostrongylus tenuis, is associated with dramatic decreases in the density of red grouse (lagopus lagopus scoticus) resulting in a significant loss of sporting income to many upland estates in the uk. in this article peter hudson and andrew dobson describe the dynamics of the grouse-t. tenuis system, show that the parasites can cause population crashes and present preliminary findings from the development of new control methods. | 1989 | 15463233 |
| rising burden of immature sheep ticks (ixodes ricinus) on red grouse (lagopus lagopus scoticus) chicks in the scottish uplands. | the sheep tick ixodes ricinus (l.) (acari: ixodidae) is an ectoparasite of major economic and pathogenic importance in scotland. its distribution in the scottish uplands is assumed to be governed by the abundance and distribution of its definitive hosts (deer and sheep) and climatic variables such as temperature and rainfall. as the numbers of its major host in scotland, red deer, have increased dramatically and climatic conditions have become more favourable, the level of parasitism could have ... | 2004 | 15009449 |
| interactions between population processes in a cyclic species: parasites reduce autumn territorial behaviour of male red grouse. | the causes of population cycles fascinate and perplex ecologist. most work have focused on single processes, whether extrinsic or intrinsic, more rarely on how different processes might interact to cause or mould the unstable population dynamics. in red grouse (lagopus lagopus scoticus), two causal mechanisms have been supported: territorial behaviour (changes in autumn aggressiveness) and parasites (parasite induced reduction in fecundity). here, we report on how these two regulatory processes ... | 2005 | 15891828 |
| ticks need not bite their red grouse hosts to infect them with louping ill virus. | for pathogens transmitted by biting vectors, one of the fundamental assumptions is often that vector bites are the sole or main route of host infection. here, we demonstrate experimentally a transmission route whereby hosts (red grouse, lagopus lagopus scoticus) became infected with a member of the tick-borne encephalitis virus complex, louping ill virus, after eating the infected tick vector. furthermore, we estimated from field observations that this mode of infection could account for 73-98% ... | 2004 | 15252984 |
| comparative tissue distribution of metals in birds in sweden using icp-ms and laser ablation icp-ms. | cadmium, copper, lead, palladium, platinum, rhodium, and zinc profiles were investigated along feather shafts of raptor and other bird species by laser ablation inductively coupled plasma mass spectrometry (la-icp-ms). the distribution of external versus internal metal contamination of feathers was investigated. the species examined were peregrine falcon (falco peregrinus), sparrowhawk ( accipiter nisus), willow grouse (lagopus lagopus), and house sparrow (passer domesticus) in sweden. for habit ... | 2004 | 15386152 |
| lead concentrations in ruffed grouse, rock ptarmigan, and willow ptarmigan in québec. | between 1996 and 1998, ruffed grouse, spruce grouse, willow ptarmigan, and rock ptarmigan harvested by hunters in québec were examined for lead contamination. on examination of the gizzards of these birds, lead shot was found only in ruffed grouse (1.2%). the probability of ingestion of lead shot by grouse and ptarmigans is low. analyses of the lead concentrations in the wing bones of grouse and ptarmigans and in the muscle tissue of ptarmigans were conducted. although differences were observed ... | 2005 | 15959706 |
| organochlorines and trace elements in upland game birds harvested in canada. | american woodcock, common snipe, two species of ptarmigan (willow and rock), and three species of grouse (ruffed, spruce, and sharp-tailed) were collected from 21 locations between 1991 and 1994 as part of a nationwide survey of contaminants in game birds harvested in canada. breast muscle was analysed for organochlorines (chlorobenzenes, hexachlorocyclohexanes, chlordane-related compounds, ddt metabolites, mirex, dieldrin, and pcbs) and trace elements (hg, cd, se, and as). the concentrations of ... | 2006 | 16055172 |
| interactions between intrinsic and extrinsic mechanisms in a cyclic species: testosterone increases parasite infection in red grouse. | field studies of mechanisms involved in population regulation have tended to focus on the roles of either intrinsic or extrinsic factors, but these are rarely mutually exclusive and their interactions can be crucial in determining dynamics. experiments on red grouse lagopus lagopus scoticus have shown that population instability can be caused both by the effects of a parasitic nematode, trichostrongylus tenuis, on host production or by changes in testosterone influencing aggressive behaviour and ... | 2005 | 16191643 |
| vector-borne parasites decrease host mobility: a field test of freeze or flee behaviour of willow ptarmigan. | transmission mode has been suggested to be a strong predictor of virulence. according to theory, the transmission of vector-borne parasites should be less dependent on host mobility than directly transmitted parasites. this could select for increased exploitation of host resources in parasites transmitted by vectors, which may be manifested as higher virulence. here, we test the prediction that there is an association between transmission mode and the effect on host mobility by comparing parasit ... | 2006 | 16696980 |
| demographic consequences of age-structure in extreme environments: population models for arctic and alpine ptarmigan. | organisms living in arctic and alpine environments are increasingly impacted by human activities. to evaluate the potential impacts of global change, a better understanding of the demography of organisms in extreme environments is needed. in this study, we compare the age-specific demography of willow ptarmigan (lagopus lagopus) breeding at arctic and subalpine sites, and white-tailed ptarmigan (l. leucurus) breeding at an alpine site. rates of egg production improved with age at the alpine and ... | 2005 | 16010534 |
| ornamental comb colour predicts t-cell-mediated immunity in male red grouse lagopus lagopus scoticus. | sexual ornaments might reliably indicate the ability to cope with parasites and diseases, and a better ability to mount a primary inflammatory response to a novel challenge. carotenoid-based ornaments are amongst the commonest sexual signals of birds and often influence mate choice. because carotenoids are immuno-stimulants, signallers may trade-off allocating these to ornamental colouration or using them for immune responses, so carotenoid-based ornaments might be particularly useful as honest ... | 2008 | 17898979 |
| separating behavioral and physiological mechanisms in testosterone-mediated trade-offs. | testosterone often mediates trade-offs between reproduction and other life-history traits, which are usually investigated using testosterone implants. however, this approach does not distinguish between the physiological and behavioral effects of testosterone. we studied a wild game bird, the red grouse lagopus lagopus scoticus, and took a new approach to investigate mechanisms linking elevated testosterone to increased parasite intensity. we caught males in autumn, removed their parasites, impl ... | 2005 | 16032571 |
| testosterone and autumn territorial behavior in male red grouse lagopus lagopus scoticus. | in many bird species, males exhibit territorial aggression outside the breeding season, when testosterone concentrations are low and may not regulate territorial behaviors. the hormonal regulation of aggression at this time of year has only been studied in passerine birds. here, we investigated the role of testosterone in the regulation of aggression in a non-passerine bird, the red grouse lagopus lagopus scoticus. male red grouse are aggressive in early spring when breeding starts, in autumn wh ... | 2005 | 15811360 |
| nematode parasites reduce carotenoid-based signalling in male red grouse. | carotenoids determine the yellow-red colours of many ornaments, which often function as signals of quality. carotenoid-based signalling may reliably advertise health and should be particularly sensitive to parasite infections. nematodes are among the commonest parasites of vertebrates, with well-documented negative effects on their hosts. however, to date, little is known about the effects that these parasites may have on carotenoid-based signalling. tetraonid birds (grouse) exhibit supra-orbita ... | 2007 | 17264052 |
| trends in ixodid tick abundance and distribution in great britain. | the popular, but rarely documented, view in britain is that ticks have increased in distribution and abundance over recent years. to assess this, we gathered evidence for changes in tick distribution and abundance by distributing a survey questionnaire throughout britain and by analysing trends in the prevalence of tick infestation on red grouse chicks lagopus lagopus scoticus latham (galliformes: tetranoidae), gathered over 19 years at three scottish sites, and on deer (cetartiodactyla: cervida ... | 2008 | 18816272 |
| monitoring of raptors and their contamination levels in norway. | this article summarizes results from raptor monitoring and contamination studies in norway of the golden eagle, gyrfalcon, white-tailed sea eagle, osprey, peregrine, and merlin. golden eagle and gyrfalcon populations have been monitored since 1990 as part of the "monitoring programme for terrestrial ecosystems" (tov). no long-term trend in the population size or productivity of golden eagle has been shown in any of the 5 study areas. the reproductive output of gyrfalcon is monitored in 3 areas. ... | 2008 | 18833794 |
| factors affecting unintentional harvesting selectivity in a monomorphic species. | 1. changes in the abundance of populations have always perplexed ecologists but long-term studies are revealing new insights into population dynamic processes. long-term data are often derived from harvest records although many wild populations face high harvesting pressures leading to overharvesting and extinction. additionally, harvest records used to describe population processes such as fluctuations in abundance and reproductive success often assume a random off-take. 2. selective harvesting ... | 2009 | 19021782 |
| interactions between harvesting, noise and territoriality in a model of red grouse population cycles. | 1. population cycles are mostly thought to arise through extrinsic rather than intrinsic processes. however, in red grouse (lagopus lagopus scoticus), intrinsic male territoriality has been proposed as a driver of the cycles, possibly in conjunction with an extrinsic interaction with specialist parasitic worms. here we examine how harvesting and environmental noise may also interact with territoriality to determine how grouse populations cycle. 2. a stochastic model of grouse dynamics based on t ... | 2009 | 19021784 |
| sensitivity to assumptions in models of generalist predation on a cyclic prey. | ecological theory predicts that generalist predators should damp or suppress long-term periodic fluctuations (cycles) in their prey populations and depress their average densities. however, the magnitude of these impacts is likely to vary depending on the availability of alternative prey species and the nature of ecological mechanisms driving the prey cycles. these multispecies effects can be modeled explicitly if parameterized functions relating prey consumption to prey abundance, and realistic ... | 2007 | 18027760 |
| a multilocus assay reveals high nucleotide diversity and limited differentiation among scandinavian willow grouse (lagopus lagopus). | there is so far very little data on autosomal nucleotide diversity in birds, except for data from the domesticated chicken and some passerines species. estimates of nucleotide diversity reported so far in birds have been high (approximately 10(-3)) and a likely explanation for this is the generally higher effective population sizes compared to mammals. in this study, the level of nucleotide diversity has been examined in the willow grouse, a non-domesticated bird species from the order galliform ... | 2008 | 19099558 |
| temporal changes in kin structure through a population cycle in a territorial bird, the red grouse lagopus lagopus scoticus. | populations of red grouse (lagopus lagopus scoticus) undergo regular multiannual cycles in abundance. the 'kinship hypothesis' posits that such cycles are caused by changes in kin structure among territorial males producing delayed density-dependent changes in aggressiveness, which in turn influence recruitment and regulate density. the kinship hypothesis makes several specific predictions about the levels of kinship, aggressiveness and recruitment through a population cycle: (i) kin structure w ... | 2008 | 18430149 |
| characterising functionally important and ecologically meaningful genetic diversity using a candidate gene approach. | over the past two decades the fields of molecular ecology and population genetics have been dominated by the use of putatively neutral dna markers, primarily to resolve spatio-temporal patterns of genetic variation to inform our understanding of population structure, gene flow and pedigree. recent emphasis in comparative functional genomics, however, has fuelled a resurgence of interest in functionally important genetic variation that underpins phenotypic traits of adaptive or ecological signifi ... | 2010 | 18803023 |
| absence of three known benzimidazole resistance mutations in trichostrongylus tenuis, a nematode parasite of avian hosts. | benzimidazole (bz) resistance is widespread in nematode parasites of livestock, but very little is known about the levels of bz resistance in parasites with avian hosts. we investigated bz resistance in trichostrongylus tenuis, a nematode parasite of red grouse, lagopus lagopus scotica. bz anthelmintics had been in use in this system for up to 15 years, yet existing phenotypic evidence for resistance was inconclusive. we screened 1530 individuals from 14 populations at the principal beta-tubulin ... | 2008 | 19027239 |
| bone lead levels and lead isotope ratios in red grouse from scottish and yorkshire moors. | leg and foot bones of adult and juvenile red grouse (lagopus lagopus scoticus) were collected from hunter-shot birds on two scottish estates (glendye and invermark) and one yorkshire estate in september, 2003. the lead content of bones was measured by atomic absorption spectrophotometry, and corresponding stable lead isotopes (pb(204, 206, 207, 208)) by inductively coupled plasma mass spectrometry. at the glendye (n=111) and invermark (n=85) estates, relatively few birds (5.4% and 3.5%, respecti ... | 2009 | 19264349 |
| physiological stress mediates the honesty of social signals. | extravagant ornaments used as social signals evolved to advertise their bearers' quality. the immunocompetence handicap hypothesis proposes that testosterone-dependent ornaments reliably signal health and parasite resistance; however, empirical studies have shown mixed support. alternatively, immune function and parasite resistance may be indirectly or directly related to glucocorticoid stress hormones. we propose that an understanding of the interplay between the individual and its environment, ... | 2009 | 19319197 |
| fitting models of multiple hypotheses to partial population data: investigating the causes of cycles in red grouse. | there are two postulated causes for the observed periodic fluctuations (cycles) in red grouse (lagopus lagopus scoticus). the first involves interaction with the parasitic nematode trichostrongylus tenuis. the second invokes delayed regulation through the effect of male aggressiveness on territoriality. empirical evidence exists to support both hypotheses, and each hypothesis has been modeled deterministically. however, little effort has gone into looking at the combined effects of the two mecha ... | 2009 | 19627232 |
| testing the interactive effects of testosterone and parasites on carotenoid-based ornamentation in a wild bird. | testosterone underlies the expression of most secondary sexual traits, playing a key role in sexual selection. however, high levels might be associated with physiological costs, such as immunosuppression. immunostimulant carotenoids underpin the expression of many red-yellow ornaments, but are regulated by testosterone and constrained by parasites. we manipulated testosterone and nematode burdens in red grouse (lagopus lagopus scoticus) in two populations to tease apart their effects on caroteno ... | 2010 | 20536879 |
| altitudinal patterns of tick and host abundance: a potential role for climate change in regulating tick-borne diseases? | the impact of climate change on vector-borne infectious diseases is currently controversial. in europe the primary arthropod vectors of zoonotic diseases are ticks, which transmit borrelia burgdorferi sensu lato (the agent of lyme disease), tick-borne encephalitis virus and louping ill virus between humans, livestock and wildlife. ixodes ricinus ticks and reported tick-borne disease cases are currently increasing in the uk. theories for this include climate change and increasing host abundance. ... | 2010 | 19685082 |
| is hunting mortality additive or compensatory to natural mortality? effects of experimental harvest on the survival and cause-specific mortality of willow ptarmigan. | 1. the effects of harvest on the annual and seasonal survival of willow ptarmigan lagopus lagopus l. were tested in a large-scale harvest experiment. management units were randomly assigned to one of three experimental treatments: 0%, 15% or 30% harvest. seasonal quotas were based on the experimental treatment and estimates of bird density before the hunting season. survival rates and hazard functions for radio-marked ptarmigan were then estimated under the competing risks of harvest and natural ... | 2010 | 21054381 |
| physiological stress links parasites to carotenoid-based colour signals. | vertebrates commonly use carotenoid-based traits as social signals. these can reliably advertise current nutritional status and health because carotenoids must be acquired through the diet and their allocation to ornaments is traded-off against other self-maintenance needs. we propose that the coloration more generally reveals an individual's ability to cope with stressful conditions. we tested this idea by manipulating the nematode parasite infection in free-living red grouse (lagopus lagopus s ... | 2010 | 20074170 |
| quantifying fenbendazole and its metabolites in self-medicating wild red grouse lagopus lagopus scoticus using an hplc-ms-ms approach. | on red grouse estates in the uk the nematode parasite trichostrongylus tenuis is often controlled by application of grit medicated with the anthelmintic fenbendazole (fbz). to date, assessment of the efficacy has been inhibited by the inability to quantify uptake of fbz by the birds. we have developed a simple and sensitive hplc-ms-ms method for detecting and quantifying fbz and its metabolites from a 300 mg sample of red grouse liver. this method could be used to improve the efficacy of medicat ... | 2010 | 21236579 |
| condition- and parasite-dependent expression of a male-like trait in a female bird. | in many species, females display brightly coloured and elaborate traits similar to those that males use in intra- and inter-sexual selection processes. these female characters are sometimes related to fitness, and might function as secondary sexual characteristics that have evolved through sexual selection. here, we used descriptive data from 674 females in 10 populations and an experimental removal of trichostrongylus tenuis parasites in four populations, to examine the effects of season, age, ... | 2011 | 21247939 |
| identification of genes responding to nematode infection in red grouse. | the identification of genes involved in a host's response to parasite infection provides both a means for understanding the pathways involved in immune defence and a target for examining host-parasite co-evolution. most studies rely on a candidate gene approach derived from model systems to identify gene targets of interest, and there have been a dearth of studies geared towards providing a holistic overview of immune response from natural populations. we carried out an experiment in a natural p ... | 2011 | 21429137 |
| impact of unintentional selective harvesting on the population dynamics of red grouse. | 1. the effect of selective exploitation of certain age, stage or sex classes (e.g., trophy hunting) on population dynamics is relatively well studied in fisheries and sexually dimorphic mammals. 2. harvesting of terrestrial species with no morphological differences visible between the different age and sex classes (monomorphic species) is usually assumed to be nonselective because monomorphicity makes intentionally selective harvesting pointless and impractical. but harvesting of the red grouse ... | 2011 | 21595686 |
| oxidative stress and the effect of parasites on a carotenoid-based ornament. | oxidative stress, the physiological condition whereby the production of reactive oxygen and nitrogen species overwhelms the capacity of antioxidant defences, causes damage to key bio-molecules. it has been implicated in many diseases, and is proposed as a reliable currency in the trade-off between individual health and ornamentation. whether oxidative stress mediates the expression of carotenoid-based signals, which are among the commonest signals of many birds, fish and reptiles, remains contro ... | 2010 | 20086124 |
| genetic diversity and differentiation among lagopus lagopus populations in scandinavia and scotland: evolutionary significant units confirmed by snp markers. | single nucleotide polymorphism in four scandinavian populations of willow grouse (lagopus lagopus) and two scottish populations of red grouse (lagopus lagopus scoticus) were assessed at 13 protein-coding loci. we found high levels of diversity, with one substitution every 55 bp as an average and a total of 76 unlinked parsimony informative snps. different estimators of genetic diversity such as: number of synonymous and non-synonymous sites, average number of alleles, number and percentage of po ... | 2010 | 20636891 |
| transcriptomic response of red grouse to gastro-intestinal nematode parasites and testosterone: implications for population dynamics. | a central issue in ecology is in understanding the relative influences of intrinsic and extrinsic effects on population regulation. previous studies on the cyclic population dynamics of red grouse (lagopus lagopus scoticus) have emphasized the destabilizing effects of either nematode parasites or territorial behaviour and aggression. the potential interacting effects of these processes, mediated through density-dependent, environmentally induced alterations of host immunocompetence influencing s ... | 2010 | 21073676 |
| environmental heterogeneity influences the reliability of secondary sexual traits as condition indicators. | numerous studies have shown positive associations between ornaments and condition, as predicted by indicator models of sexual selection. however, this idea is continuously challenged by opposite results, which reveal our lack of full understanding of how sexual selection works. environmental heterogeneity may explain such inconsistencies, but valid field tests of this idea are currently lacking. we first analysed the relationship between condition and ornament expression from nine populations ov ... | 2012 | 22022806 |
| the importance of willow thickets for ptarmigan and hares in shrub tundra: the more the better? | in patchy habitats, the relationship between animal abundance and cover of a preferred habitat may change with the availability of that habitat, resulting in a functional response in habitat use. here, we investigate the relationship of two specialized herbivores, willow ptarmigan (lagopus lagopus) and mountain hare (lepus timidus), to willows (salix spp.) in three regions of the shrub tundra zone-northern norway, northern european russia and western siberia. shrub tundra is a naturally patchy h ... | 2011 | 21833646 |
| The ornament-condition relationship varies with parasite abundance at population level in a female bird. | Environmental heterogeneity is expected to create variation in the ornament-condition relationship. This topic has been studied in males with less attention being given to females. Here, we explore inter-population variation in the relationship between the size of a male-like trait, supra-orbital combs, and body mass in female red grouse Lagopus lagopus scoticus. We used the abundance of the nematode Trichostrongylus tenuis, a parasite with strong negative effects on this species, as a proxy of ... | 2011 | 21858505 |
| Enhanced control of sheep ticks in upland sheep flocks: repercussions for red grouse co-hosts. | Sheep ticks Ixodes ricinus (Acari: Ixodidae) and tick-borne diseases cause major economic losses in both upland sheep farming and moorland shoots of red grouse Lagopus lagopus scoticus. Sheep were treated with acaricide four times between March and October and double-vaccinated against louping ill virus (LIV), instead of the conventional regime of two acaricide treatments and no vaccinations, on two moors in northern England. Enhanced treatment started at Westerdale Moor in 1995 and at Danby Moo ... | 2011 | 22112150 |
| electrophoretic separation of serum esterases in willow ptarmigan (lagopus lagopus lagopus). | | 2012 | 3436830 |
| micromorphological studies on the small intestine and caeca in wild and captive willow grouse (lagopus lagopus lagopus). | | 2004 | 506873 |
| helminths from willow grouse ( lagopus lagopus ) in two localities in north norway. | a total of 77 adult and 123 juvenile willow grouse ( lagopus lagopus ) from the island of karlsöy, and 75 adult and 63 juvenile willow grouse from sennaland on the mainland of north norway were examined for helminths. raillietina urogalli and hymenolepis microps , and ascaridia compar and syngamus trachea were found. all four species occurred regularly in grouse from karlsöy between april and september-october, but only h. microps was frequently found in birds from sennaland. s. trachea only par ... | 1977 | 24228962 |
| louping ill virus in the uk: a review of the hosts, transmission and ecological consequences of control. | louping ill virus (liv) is a tick-borne flavivirus that is part of the tick-borne encephalitis complex of viruses (tbev) and has economic and welfare importance by causing illness and death in livestock, especially sheep, ovies aries, and red grouse, lagopus lagopus scoticus, an economically valuable gamebird. unlike western tbev which is found primarily in woodlands and is reservoired by small rodents, liv is not generally transmitted by small rodents but instead by sheep, red grouse and mounta ... | 2016 | 26205612 |
| a model to test how ticks and louping ill virus can be controlled by treating red grouse with acaricide. | ticks are the most important vectors of disease-causing pathogens in europe. in the u.k., ixodes ricinus l. (ixodida: ixodidae) transmits louping ill virus (liv; flaviviridae), which kills livestock and red grouse, lagopus lagopus scoticus lath. (galliformes: phasianidae), a valuable game bird. tick burdens on grouse have been increasing. one novel method to reduce ticks and liv in grouse may be acaricide treatment. here, we use a mathematical model parameterized with empirical data to investiga ... | 2013 | 23088727 |
| an alternative to killing? treatment of reservoir hosts to control a vector and pathogen in a susceptible species. | parasite-mediated apparent competition occurs when one species affects another through the action of a shared parasite. one way of controlling the parasite in the more susceptible host is to manage the reservoir host. culling can cause issues in terms of ethics and biodiversity impacts, therefore we ask: can treating, as compared to culling, a wildlife host protect a target species from the shared parasite? we used susceptible infected recovered (sir) models parameterized for the tick-borne loup ... | 2013 | 22939093 |
| spread of cryptosporidium baileyi in red grouse lagopus lagopus scoticus. | | 2014 | 24934399 |
| cycles in voles and small game in relation to variations in plant production indices in northern sweden. | population dynamics for voles (cricetidae), tengmalm's owl (aegolius funereus (l.)), red fox (vulpes vulpes (l.)) willow grouse (lagopus lagopus (l.)), black grouse (lyrurus tetrix (l.)), capercaillie (tetrao urogallus l.), hazel hen (tetrastes bonasia (l.)), mountain hare (lepus timidus l.) and tularemia (francisella tularensis (mccoy & chapin)) and game bird recruitment were studied by index methods in northern sweden. in addition contemporary temperature records and spruce (picea abies (l.) k ... | 1986 | 28311702 |
| digging for gold nuggets: uncovering novel candidate genes for variation in gastrointestinal nematode burden in a wild bird species. | the extent to which genotypic variation at a priori identified candidate genes can explain variation in complex phenotypes is a major debate in evolutionary biology. whereas some high-profile genes such as the mhc or mc1r clearly do account for variation in ecologically relevant characters, many complex phenotypes such as response to parasite infection may well be underpinned by a large number of genes, each of small and effectively undetectable effect. here, we characterize a suite of novel can ... | 2015 | 25752450 |