| 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 |
| effects of seasonal weather on breeding phenology and reproductive success of alpine ptarmigan in colorado. | animal populations occurring at high elevations are often assumed to be in peril of extinctions or local extirpations due to elevational-dispersal limitations and thermoregulatory constraints as habitats change and warm. however, long-term monitoring of high-elevation populations is uncommon relative to those occurring at lower elevations, and evidence supporting this assumption is limited. we analyzed 45 years of reproductive data for two colorado populations of white-tailed ptarmigan (lagopus ... | 2016 | 27420478 |
| two new species of coccidia, eimeria leucuri and e. oreoecetes (protozoa: eimeriidae), in grouse from colorado. | eimeria leucuri is described from white-tailed ptarmigan (lagopus leucurus), and e. oreoecetes from white-tailed ptarmigan and blue grouse (dendragapus obscurus) from colorado. oocysts of e. leucuri are ellipsoidal, 26.6 by 17.7 micron, each bearing a micropyle, micropyle cap, up to 4 polar granules, but no oocyst residuum. the lemon-shaped sporocysts are 15.4 by 6.7 micron, and have stieda bodies and large amounts of sporocyst residuum. the sporocyst contents are enclosed in a membrane. oocysts ... | 1979 | 448611 |
| cadmium toxicity among wildlife in the colorado rocky mountains. | cadmium is known to be both extremely toxic and ubiquitous in natural environments. it occurs in almost all soils, surface waters and plants, and it is readily mobilized by human activities such as mining. as a result, cadmium has been named as a potential health threat to wildlife species; however, because it exists most commonly in the environment as a trace constituent, reported incidences of cadmium toxicity are rare. here we have measured trace metals in the food web and tissues of white-ta ... | 2000 | 10910356 |
| mismatches between breeding phenology and resource abundance of resident alpine ptarmigan negatively affect chick survival. | phenological mismatches-defined here as the difference in reproductive timing of an individual relative to the availability of its food resources-occur in many avian species. mistiming breeding activities in environments with constrained breeding windows may have severe fitness costs due to reduced opportunities for repeated breeding attempts. therefore, species occurring in alpine environments may be particularly vulnerable.we studied fitness consequences of timing of breeding in an alpine-ende ... | 2019 | 31380043 |
| environmental gradients of selection for an alpine-obligate bird, the white-tailed ptarmigan (lagopus leucura). | the warming climate will expose alpine species adapted to a highly seasonal, harsh environment to novel environmental conditions. a species can shift their distribution, acclimate, or adapt in response to a new climate. alpine species have little suitable habitat to shift their distribution, and the limits of acclimation will likely be tested by climate change in the long-term. adaptive genetic variation may provide the raw material for species to adapt to this changing environment. here, we use ... | 2020 | 32807852 |
| temperature regulation in the white-tailed ptarmigan, lagopus leucurus. | | 1968 | 5650476 |
| costs and benefits of nest cover for ptarmigan: changes within and between years. | selecting an 'optimal' nest site is believed to be an important component of fitness for birds, but paradoxically there is often considerable intraspecific variation in nest sites. few studies have tested whether nest-site selection by birds changes after experience with nest predators. using data collected over 9 years, we examined within- and between-year variation in 331 nests of white-tailed ptarmigan, lagopus leucurus. we found the first direct evidence for a fitness trade-off with amount o ... | 1998 | 9819329 |
| effect of high altitude and in vivo adenosine/(&bgr;)-adrenergic receptor blockade on atp and 2,3bpg concentrations in red blood cells of avian embryos | in chick embryos, developmental changes of the blood oxygen tension control hemoglobin (hb) oxygen affinity via modulation of atp and 2, 3bpg concentrations in red blood cells. hypoxia, which is a normal developmental condition for late chick embryos, causes a decrease of the red cell atp concentration (and increase of red cell oxygen affinity) as well as activation of 2,3bpg synthesis via cyclic amp-dependent signaling. adenosine and catecholamines have been implicated as signaling substances i ... | 1999 | 10504314 |
| signatures of large-scale and local climates on the demography of white-tailed ptarmigan in rocky mountain national park, colorado, usa. | global climate change may impact wildlife populations by affecting local weather patterns, which, in turn, can impact a variety of ecological processes. however, it is not clear that local variations in ecological processes can be explained by large-scale patterns of climate. the north atlantic oscillation (nao) is a large-scale climate phenomenon that has been shown to influence the population dynamics of some animals. although effects of the nao on vertebrate population dynamics have been stud ... | 2002 | 12242476 |
| genetic and ecological data provide incongruent interpretations of population structure and dispersal in naturally subdivided populations of white-tailed ptarmigan (lagopus leucura). | the dispersal of individuals among populations affects the demographic and adaptive trajectories of animal populations and is fundamental to understanding population dynamics. white-tailed ptarmigan (lagopus leucura) are a high elevation grouse species that live year-round in patchily distributed alpine areas in western north america. we investigated the patterns of dispersal and identified barriers to gene flow for a threatened subspecies (l. l. saxatilis) endemic to vancouver island, canada. c ... | 2008 | 18363666 |
| influence of life history strategies on sensitivity, population growth and response to climate for sympatric alpine birds. | the life history strategy of a species can influence how populations of that species respond to environmental variation. in this study, we used a matrix modeling approach to examine how life history differences among sympatric rock and white-tailed ptarmigan affect the influence of demographic rates on population growth (λ) and the potential response to a changing climate. rock ptarmigan have a slower life history strategy than white-tailed ptarmigan in the study region with lower annual reprodu ... | 2012 | 22747571 |
| mother knows best: functionally referential alarm calling in white-tailed ptarmigan. | functionally referential alarm calls have stimulus specificity, distinct acoustic structure, and elicit different escape responses that are appropriate to the threat. the mechanisms by which escape responses are evoked are not fully understood and may range from eliciting innate responses to conveying representational information. white-tailed ptarmigan (lagopus leucurus) are a long-lived alpine tundra grouse, which are preyed upon by aerial and terrestrial predators. we investigated the hypothe ... | 2014 | 24132414 |
| effects of climate change on habitat availability and configuration for an endemic coastal alpine bird. | north america's coastal mountains are particularly vulnerable to climate change, yet harbour a number of endemic species. with little room "at the top" to track shifting climate envelopes, alpine species may be especially negatively affected by climate-induced habitat fragmentation. we ask how climate change will affect the total amount, mean patch size, and number of patches of suitable habitat for vancouver island white-tailed ptarmigan (lagopus leucura saxatilis; viwtp), a threatened, endemic ... | 2015 | 26529306 |
| rhabdometra alpinensis n.sp.(cestoda: paruterinida: dilepididea) from southern white-tailed ptarmigan (lagopus leucurus altipetens osgood) in colorado, u.s.a., with a key to the species of rhabdometra cholodkowsky, 1906. | | 1978 | 647529 |