Calidris Ptilocnemis Research Articles

Inventory of Lowland-Breeding Birds on the Alaska Peninsula

AbstractWe conducted the first systematic inventory of birds in the lowlands (areas ≤100 m above sea level) of the Alaska Peninsula during summers of 2004–2007 to determine their breeding distributions and habitat associations in this remote region. Using a stratified random survey design, we allocated sample plots by elevation and land cover with a preference for wetland cover types used by shorebirds, a group of particular interest to land managers. We surveyed birds during 10-min counts at 792 points across 52, 5 km × 5 km sample plots distributed from south of the Naknek River (58.70°N,157.00°W) to north of Port Moller (56.00°N,160.52°W). We detected 95 bird species including 19 species of shorebirds and 34 species (36% of total) considered at the time to be of conservation concern for the land managers in the region. The most numerous shorebirds on point counts were dunlin Calidris alpina, short-billed dowitcher Limnodromus griseus, and Wilson's snipe Gallinago delicata. We found the breeding-season endemic marbled godwit Limosa fedoa beringiae at 20 plots within a 3,000-km2 area from north of Ugashik Bay to just north of Port Heiden and east to the headwaters of the Dog Salmon and Ugashik rivers. The most abundant passerines on point counts were American tree sparrow Spizelloides arborea, Lapland longspur Calcarius lapponicus, and savannah sparrow Passerculus sandwichensis. Sandhill crane Antigone canadensis, glaucous-winged gull Larus glaucescens, and greater scaup Aythya marila were also relatively abundant. We categorized habitat associations for 30 common species and found that lowland herbaceous vegetation supported wetland-focused species including sandhill crane, marbled godwit, short-billed dowitcher, and dunlin; whereas, dwarf shrub-ericaceous vegetation supported tundra-associated species such as willow ptarmigan Lagopus lagopus, rock sandpiper Calidris ptilocnemis, and American pipit Anthus rubescens. Tall shrub vegetation was important to several species of warblers and sparrows, as well as one species of shorebird (greater yellowlegs Tringa melanoleuca). We found that point counts augmented with incidental observations provided an almost complete inventory of lowland-breeding species on the study area. These data form a baseline to monitor any future changes in bird distribution and abundance on the Alaska Peninsula.

Assessment of bioavailable hydrocarbons in Pribilof Island rock sandpiper fall staging areas and overwintering habitat

At present, significant adverse hydrocarbon influence on the Pribilof Island rock sandpiper (Calidris ptilocnemis ptilocnemis) is unlikely. Almost the entire population overwinters in Cook Inlet and breeds on four Bering Sea islands. Passive samplers deployed several times in a three year period and corresponding sediment and soft tissue samples on St. Paul Island and in Cook Inlet generally accumulated small quantities of polycyclic aromatic hydrocarbons (PAHs). Composition was consistent with oil in <15% of the passive samplers and rarely in soft tissue. Total PAH concentrations in corresponding sediment were very low (<42ng/g dry weight); composition was consistent with oil in 39% of these samples and biomarker composition confirmed this on St. Paul Island. However, composition was dominated by normal alkanes from natural sources.

Passive recovery of an island bird community after rodent eradication

The number and scale of island invasive species eradications is growing, but quantitative evidence of the conservation efficacy of passive recovery is limited. We compare relative abundances of breeding birds on Hawadax Island (formerly named Rat island), Aleutian Archipelago, Alaska, pre- and post- rat eradication to examine short-term (<1 year post-eradication) changes due to rodenticide application, and medium-term (5 years post-eradication) changes due to the absence of invasive rats. In the short term, Bald Eagle (Haliaeetus leucocephalus) numbers decreased from 24 individuals pre-eradication to two individuals <1 year post-eradication, but recovered to 10 individuals (42 % of pre-eradication) 5 years post-eradication, with all individuals nesting (63 % of the pre-eradication nesting). Five years post-eradication relative abundances of most terrestrial birds surveyed using point counts either significantly increased [Gray-crowned Rosy Finch (Leucosticte tephrocotis), Lapland Longspur (Calcarius lapponicus), Snow Bunting (Plectrophenax nivalis), Song Sparrow (Melospiza melodia)] or did not differ [Pacific Wren (Troglodytes troglodytes)]. Shorebirds also increased 5 years post-eradication with Black Oystercatchers (Haematopus palliates) increasing fivefold, and Rock Sandpiper (Calidris ptilocnemis) nesting increasing from one to five nests. We confirmed two species of ground nesting seabirds [Tufted Puffin (Fratercula cirrhata) and Leach’s Storm-petrel (Oceanodroma leucohoa)] as nesting (puffin) or engaged in courtship behavior (Storm-petrel) 5 years post-eradication. Our results indicate that despite the short-term impact on Bald Eagles, and without further human intervention, most terrestrial and marine birds have newly-colonized, re-colonized, or increased in abundance following the eradication of invasive rats.

Development and characterization of microsatellite loci for two species of Beringian birds, rock sandpiper (Calidris ptilocnemis) and Pacific wren (Troglodytes pacificus)

Identification and assessment of small, endemic populations are priorities for conservation. We isolated and characterized 8 microsatellite loci from rock sandpiper (Calidris ptilocnemis) and 5 microsatellite loci from Pacific wren (Troglodytes pacificus), species with endemic populations of named subspecies that are of conservation concern. Eighteen to 20 individuals of each species from several locations in Alaska were screened for polymorphism. Loci for each species showed high polymorphism, with rock sandpiper ranging from 5 to 14 alleles per locus and 0.73–0.88 expected heterozygosity and Pacific wren ranging from 5 to 14 alleles per locus and 0.55–0.91 expected heterozygosity. Loci developed for rock sandpipers were also polymorphic in closely related taxa. These loci are the first developed for either species and will be used to identify and conserve endemic populations in the Bering Sea region.

Coping with the Cold: An Ecological Context for the Abundance and Distribution of Rock Sandpipers during Winter in Upper Cook Inlet, Alaska

Shorebirds are conspicuous and abundant at high northern latitudes during spring and summer, but as seasonal conditions deteriorate, few remain during winter. To the best of our knowledge, Cook Inlet, Alaska (60.6˚ N, 151.6˚ W), is the world’s coldest site that regularly supports wintering populations of shorebirds, and it is also the most northerly nonbreeding location for shorebirds in the Pacific Basin. During the winters of 1997–2012, we conducted aerial surveys of upper Cook Inlet to document the spatial and temporal distribution and number of Rock Sandpipers (Calidris ptilocnemis) using the inlet. The average survey total was 8191 ± 6143 SD birds, and the average of each winter season’s highest single-day count was 13 603 ± 4948 SD birds. We detected only Rock Sandpipers during our surveys, essentially all of which were individuals of the nominate subspecies (C. p. ptilocnemis). Survey totals in some winters closely matched the population estimate for this subspecies, demonstrating the region’s importance as a nonbreeding resource to the subspecies. Birds were most often found at only a handful of sites in upper Cook Inlet, but shifted their distribution to more southerly locations in the inlet during periods of extreme cold. Two environmental factors allow Rock Sandpipers to inhabit Cook Inlet during winter: 1) an abundant bivalve (Macoma balthica) food source and 2) current and tidal dynamics that keep foraging substrates accessible during all but extreme periods of cold and ice accretion. C. p. ptilocnemis is a subspecies of high conservation concern for which annual winter surveys may serve as a relatively inexpensive population-monitoring tool that will also provide insight into adaptations that allow these birds to exploit high-latitude environments in winter.

Ecological correlates of variable organ sizes and fat loads in the most northerly wintering shorebirds

Shorebirds at northern latitudes during the nonbreeding season typically carry relatively large lipid stores and exhibit an up-regulation of lean tissues associated with digestion and thermogenesis. Intraspecific variation in these tissues across sites primarily reflects differences in environmental conditions. Rock (Calidris ptilocnemis (Coues, 1873)) and Purple (Calidris maritima (Brünnich, 1764)) sandpipers are closely related species having the most northerly nonbreeding distributions among shorebirds, living at latitudes up to 61°N in Cook Inlet, Alaska, and up to ∼71°N in northern Norway, respectively. Cook Inlet is the coldest known site used by nonbreeding shorebirds, and the region’s mudflats annually experience extensive coverage of foraging sites by sea and shore-fast ice. Accordingly, Rock Sandpipers increase their fat stores to nearly 20% of body mass during winter. In contrast, Purple Sandpipers exploit predictably ice-free rocky intertidal foraging sites and maintain low (&lt;6.5%) fat stores. Rock Sandpipers increase the mass of lean tissues from fall to winter, including contour feathers, stomach, and liver components. They also have greater lean pectoralis and supracoracoideus muscle and liver and kidney tissues compared with Purple Sandpipers in winter. This demonstrates a combined emphasis on digestive processes and thermogenesis, whereas Purple Sandpipers primarily augment organs associated with digestive processes. The high winter fat loads and increased lean tissues of Rock Sandpipers in Cook Inlet reflect the region’s persistent cold and abundant but sporadically unavailable food resources.

Small Population Size of the Pribilof Rock Sandpiper Confirmed through Distance-Sampling Surveys in Alaska

Abstract. The Rock Sandpiper (Calidris ptilocnemis) is endemic to the Bering Sea region and unique among shorebirds in the North Pacific for wintering at high latitudes. The nominate subspecies, the Pribilof Rock Sandpiper (C. p. ptilocnemis), breeds on four isolated islands in the Bering Sea and appears to spend the winter primarily in Cook Inlet, Alaska. We used a stratified systematic sampling design and line-transect method to survey the entire breeding range of this population during springs 2001–2003. Densities were up to four times higher on the uninhabited and more northerly St. Matthew and Hall islands than on St. Paul and St. George islands, which both have small human settlements and introduced reindeer herds. Differences in density, however, appeared to be more related to differences in vegetation than to anthropogenic factors, raising some concern for prospective effects of climate change. We estimated the total population at 19 832 birds (95% CI 17 853–21 930), ranking it among the smallest ...

Anticoagulant Residual Concentration and Poisoning in Birds Following a Large-Scale Aerial Application of 25 ppm Brodifacoum Bait for Rat Eradication on Rat Island, Alaska

Author(s): Ebbert, Steve; Burek-Huntington, Kathy | Abstract: To eradicate invasive Norway rats, an aerial broadcast of the rodenticide Brodifacoum-25W Conservation was conducted on 2,777-ha Rat Island, within the Aleutian Islands Unit of Alaska Maritime National Wildlife Refuge, between 29 September and 5 October 2008. During subsequent visits to Rat Island (in spring and fall 2009) to check for evidence of remaining rats and to look for evidence of nontarget mortality, personnel found an unexpectedly high number of dead birds: more than 420 carcasses, mostly glaucous-winged gulls and bald eagles, but also included 24 other species. Some carcasses had tissue suitable for analysis and were collected. Seventy bird carcasses were necropsied and cause of death was determined for 50 birds; 45 died of brodifacoum toxicosis. Necropsy determined almost all gulls and eagles had extensive hemorrhaging, consistent with brodifacoum poisoning. All eagles and all but 1 gull tested positive for brodifacoum residues. Positive tests for brodifacoum also were recorded for single specimens of emperor goose, northern fulmar, pelagic cormorant, peregrine falcon, rock sandpiper, and gray-crowned rosy finch. Two Lapland longspurs tested positive for exposure to brodifacoum. Nontarget bird mortality from brodifacoum exposure at Rat Island was higher than predicted in the Environmental Assessment.

Behavior and Reproductive Success of Rock Sandpipers Breeding on the Yukon-Kuskokwim River Delta, Alaska

We studied Rock Sandpiper (Calidris ptilocnemis) breeding behavior and monitored reproductive success from 1998 to 2005 on the Yukon-Kuskokwim River Delta, Alaska, USA. We banded 24 adults and monitored 45 nests. Annual return rate of adults ranged between 67 and 100%. Six pairs of Rock Sandpipers bred at our study site for ≥2 years, and among these we did not observe mate change (i.e., when both members of a pair returned and each mated with a new individual). Nests were typically initiated by mid-May and 53% of females laid second clutches if first clutches were lost through mid-June. Males regularly incubated clutches during the morning (0800–1259 hrs AKDT) and afternoon (1300–1759 hrs) and rarely during the evening (1800– 2300 hrs), whereas female incubation was relatively consistent throughout the day. Apparent nest success (percent of known nests successfully hatching >1 chick) among first and second nests was 19 and 44%, respectively (n = 45). A minimum of 44% of hatching nests fledged at least one young. Males cared for young but half of females deserted mate and brood 1–7 days post-hatch. This first description of North American Rock Sandpiper breeding behavior from a color-marked population complements previous work on this species on the Chukotsky Peninsula, Russia.

Evidence for cryptic northern refugia among high- and temperate-latitude species in Beringia

Stewart and Dalen (2008) argue that only temperate species were locked in cryptic northern refugia during Pleistocene glacial cycles, while species presently found at high latitudes had much wider distributions during glaciations. We present evidence supporting the existence of cryptic northern refugia that likely harbored both high- and temperate-latitude species in the Bering Sea region. Genetic signals of refugial isolation are found in island populations of rock ptarmigan (Lagopus muta), rock sandpiper (Calidris ptilocnemis), common raven (Corvus corax), and winter wren (Troglodytes troglodytes). These species have high-latitude, a mixture of high- and temperate-latitude, and temperate-latitude distributions. In addition, there are no data showing historically larger distributions of the high-latitude rock sandpiper or rock ptarmigan in North America during the Pleistocene. Although exact dating of isolation events is not possible using molecular genetic data, the species we examined have similar genetic signals and thus were isolated at similar times. It is evident that Pleistocene glaciations produced refugial genetic signatures among multiple bird species in the North Pacific Ocean.

Biological Impacts of Climatic Change on a Beringian Endemic: Cryptic Refugia in the Establishment and Differentiation of the Rock Sandpiper (Calidris Ptilocnemis)

The importance of climatic change on the establishment and differentiation of high-latitude species is largely unknown. Biological effects of historic climate change can be determined from historic signals in genetic data. The rock sandpiper (Calidris ptilocnemis) is a good test case for examining these biological effects because it has a known sister species, the purple sandpiper (Calidris maritima), and it is the only endemic Beringian bird with multiple described subspecies, suggesting a process of initial establishment and subsequent differentiation in the high-latitude regions of Beringia. We sequenced 2,074 bp of mitochondrial DNA from 40 rock sandpipers from nine breeding locations and four purple sandpipers. We used phylogenetic and coalescence methods to reconstruct trees and to evaluate the population demography, migration rates, and relative times of population divergence. Phylogenetic trees show that purple and rock sandpipers are monophyletic sister species. Within the rock sandpiper, clade branching patterns and coalescence estimates suggest that there were multiple refugial populations in Beringia, which correspond loosely to different glacial cycles. Rock sandpipers show the establishment, persistence, and accumulation of partitioned genetic diversity across several glacial cycles, implicating the presence of multiple cryptic biological refugia in this region through repeated cycles of climate change.