| osteological histology of the pan-alcidae (aves, charadriiformes): correlates of wing-propelled diving and flightlessness. | although studies of osteological morphology, gross myology, myological histology, neuroanatomy, and wing-scaling have all documented anatomical modifications associated with wing-propelled diving, the osteohistological study of this highly derived method of locomotion has been limited to penguins. herein we present the first osteohistological study of the derived forelimbs and hind limbs of wing-propelled diving pan-alcidae (aves, charadriiformes). in addition to detailing differences between wi ... | 2014 | 24357466 |
| aploparaksis borealis sp. n. (cestoda: hymenolepididae) from passeriform and charadriiform birds in chukotka and alaska. | aploparaksis borealis sp. n. (cestoda: hymenolepididae), from the long-tailed jaeger, stercorarisu longicaudus vieillot, on the seward peninsula, alaska, and from the red-throated pipit, anthus cervinus (pallas), and the lapland longspur, calcarius lapponicus (linnaeus), in chukotka, northestern siberia, is described. this cestode is distinguished by the structure of the cirrus and other morphologic characters from other species of aploparaksis clerc 1903 in which there are 10 rostellar hooks an ... | 1977 | 845746 |
| predation pressure by avian predators suggests summer limitation of small-mammal populations in the canadian arctic. | predation has been suggested to be especially important in simple food webs and less productive ecosystems such as the arctic tundra, but very few data are available to evaluate this hypothesis. we examined the hypothesis that avian predators could drive the population dynamics of two cyclic lemming species in the canadian arctic. a dense and diverse suite of predatory birds, including the snowy owl (bubo scandiacus), the rough-legged hawk (buteo lagopus), and the long-tailed jaeger (stercorariu ... | 2014 | 24649646 |
| response of an arctic predator guild to collapsing lemming cycles. | alpine and arctic lemming populations appear to be highly sensitive to climate change, and when faced with warmer and shorter winters, their well-known high-amplitude population cycles may collapse. being keystone species in tundra ecosystems, changed lemming dynamics may convey significant knock-on effects on trophically linked species. here, we analyse long-term (1988-2010), community-wide monitoring data from two sites in high-arctic greenland and document how a collapse in collared lemming c ... | 2012 | 22977153 |
| cyclic dynamics in a simple vertebrate predator-prey community. | the collared lemming in the high-arctic tundra in greenland is preyed upon by four species of predators that show marked differences in the numbers of lemmings each consumes and in the dependence of their dynamics on lemming density. a predator prey model based on the field-estimated predator responses robustly predicts 4-year periodicity in lemming dynamics, in agreement with long-term empirical data. there is no indication in the field that food or space limits lemming population growth, nor i ... | 2003 | 14593179 |
| differences in speciation progress in feather mites (analgoidea) inhabiting the same host: the case of zachvatkinia and alloptes living on arctic and long-tailed skuas. | recent molecular phylogenetic analyses have revealed that some apparently oligoxenous feather mite species are in fact monoxenous cryptic species with little morphological differentiation. in this study we analyzed two species, zachvatkinia isolata (avenzoariidae) and alloptes (sternalloptes) stercorarii (alloptidae) which prefer different parts of the plumage of two sister species of birds: arctic skua (stercorarius parasiticus) and long-tailed skua (s. longicaudus) breeding on tundra in the hi ... | 2015 | 25342243 |
| demographic responses of a site-faithful and territorial predator to its fluctuating prey: long-tailed skuas and arctic lemmings. | environmental variability, through interannual variation in food availability or climatic variables, is usually detrimental to population growth. it can even select for constancy in key life-history traits, though some exceptions are known. changes in the level of environmental variability are therefore important to predict population growth or life-history evolution. recently, several cyclic vole and lemming populations have shown large dynamical changes that might affect the demography or life ... | 2014 | 24128282 |
| trans-equatorial migration routes, staging sites and wintering areas of a high-arctic avian predator: the long-tailed skua (stercorarius longicaudus). | the long-tailed skua, a small (<300 g) arctic-breeding predator and seabird, is a functionally very important component of the arctic vertebrate communities in summer, but little is known about its migration and winter distribution. we used light-level geolocators to track the annual movements of eight adult birds breeding in north-east greenland (n = 3) and svalbard (n = 5). all birds wintered in the southern hemisphere (mean arrival-departure dates on wintering grounds: 24 october-21 march): f ... | 2013 | 23705000 |
| enigmatic phylogeny of skuas (aves:stercorariidae) | multiple sources of evidence show that the skuas (aves:stercorariidae) are a monophyletic group, closely related to gulls (laridae. on morphological and behavioural evidence the stercorariidae are divided into two widely divergent genera, catharacta and stercorarius, consistent with observed levels of nuclear and mitochondrial gene divergence. catharacta skuas are large-bodied and with one exception breed in the southern hemisphere. stercorarius skuas otherwise known as jaegers) are smaller bodi ... | 1997 | 9061968 |
| the genetic basis and enigmatic origin of melanic polymorphism in pomarine skuas (stercorarius pomarinus). | a key outstanding issue in adaptive evolution is the relationship between the genetics of intraspecific polymorphism and interspecific evolution. here, we show that the pale/dark ventral plumage polymorphism that occurs in both the pomarine skua (stercorarius pomarinus) and arctic skua (s. parasiticus) is the result of convergent evolution at the same locus (mc1r), involving some of the same amino acid sites. the dark melanic mc1r allele in the pomarine skua is strongly divergent from the pale m ... | 2017 | 29187628 |