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Long-distance migrants are under strong selection to arrive on their breeding grounds at a time that maximizes fitness. Many arctic birds start nesting shortly after snow recedes from their breeding sites and timing of snowmelt can vary substantially over the breeding range of widespread species. We tested the hypothesis that migration schedules of individuals co-occurring at the same non-breeding areas are adapted to average local environmental conditions encountered at their specific and distant Arctic breeding locations. We predicted that timing of breeding site availability (measured here as the average snow-free date) should explain individual variation in departure time from shared non-breeding areas. We tested our prediction by tracking American Golden-Plovers (Pluvialis dominica) nesting across the North-American Arctic. These plovers use a non-breeding (wintering) area in South America and share a spring stopover area in the nearctic temperate grasslands, located >1,800 km away from their nesting locations. As plovers co-occur at the same non-breeding areas but use breeding sites segregated by latitude and longitude, we could disentangle the potential confounding effects of migration distance and timing of breeding site availability on individual migration schedule. As predicted, departure date of individuals stopping-over in sympatry was positively related to the average snow-free date at their respective breeding location, which was also related to individual onset of incubation. Departure date from the shared stopover area was not explained by the distance between the stopover and the breeding location, nor by the stopover duration of individuals. This strongly suggests that plover migration schedule is adapted to and driven by the timing of breeding site availability per se. The proximate mechanism underlying the variable migration schedule of individuals is unknown and may result from genetic differences or individual learning. Temperatures are currently changing at different speeds across the Arctic and this likely generates substantial heterogeneity in the strength of selection pressure on migratory schedule of arctic birds migrating sympatrically.

Breeding bird response to habitat rehabilitation after anthropogenic disturbance has received little attention in the Arctic. The North Slope of Alaska is an important breeding ground for many populations of migratory birds and has also supported major oilfields since the late 1960s. The most obvious impacts of industrial development to nesting birds are direct habitat loss and fragmentation resulting from the construction of infrastructure, along with increased mechanical noise, vehicle traffic, and other forms of anthropogenic disturbance. In response to state and federal requirements, efforts have been made to rehabilitate abandoned portions of the oilfields. We compared bird use at rehabilitation sites and at nearby paired reference sites. Densities of shorebirds and passerines varied between rehabilitation sites and reference sites, but waterfowl densities did not. Specifically, passerine and shorebird densities were higher at reference sites in the early or mid-season and lower at reference sites in the late season. Additionally, birds on rehabilitation sites were primarily observed foraging and resting, while behavior observed on paired reference sites was more diverse and included courtship displays, nesting, and aggression. Further, rehabilitation sites supported significantly fewer nests and fewer species than recorded at reference sites. Our findings suggest that sites 3 to 10 years post rehabilitation do not provide bird habitat comparable to nearby reference sites and, by extension, do not provide shorebird and passerine habitat comparable to that found prior to development. However, rehabilitation sites appear to provide adequate habitat for waterfowl and are important to shorebirds and passerines as foraging areas. Continued monitoring will be needed to establish the long-term suitability of rehabilitation sites, compared to reference sites, as breeding habitat for birds.

Semipalmated Sandpiper (Calidris pusilla) populations have undergone significant declines at core nonbreeding sites in northeastern South America. Breeding populations have also declined in the eastern North American Arctic, but appear to be stable or increasing in the central and western Arctic. To identify vulnerable populations and sites, we documented the migratory connectivity of Semipalmated Sandpipers using light-level geolocators, deploying 250 at 8 Arctic sites across the species' breeding range from 2011 to 2015, plus 87 at a single wintering site in northeastern Brazil in 2013 and 2014. We recovered 59 units and resighted 7 more (26% return rate) on the breeding grounds, but none at the nonbreeding site. We recovered only ∼3% of units deployed in 2013 at eastern Arctic breeding sites, but recovered 33% of those deployed in 2015. Overall, birds with geolocators were 57% as likely to return as those carrying alphanumeric flags. Stopover durations at prairie sites (mean: 8.7 days southbou...

The Black Oystercatcher is a large shorebird found along the west coast of North America. Because of its small global population size, low reproductive rate, and dependence on rocky intertidal habitats, it is considered a “species of high conservation concern” and may act as an indicator of intertidal ecosystem health. In 2015, Portland Audubon initiated a 3-y shore-based population survey in Oregon building upon long-term monitoring previously conducted by the US Geological Survey (USGS) and others. The objectives were to: (1) estimate the current minimum population of breeding Black Oystercatchers in Oregon and compare to previous estimates; (2) document oystercatcher abundance on shoreline adjacent to the Oregon's system of Marine Reserves (MRs) and Marine Protected Areas (MPAs); and (3) describe the spatial distribution of breeding oystercatchers along the coast. We targeted all rocky shoreline along Oregon's coastline to conduct abundance surveys each spring from 2015–2017. A total of 75 survey routes were sampled using a standardized land-based survey protocol. Trained volunteer community scientists conducted the majority of the surveys. We used N-mixture statistical models to estimate oystercatcher population size and probability of detection. Population estimates from the best-fitting models were consistent, with estimates ranging from 506 oystercatchers in 2016 (95% credible interval, 463–560) to 629 (548–743) in 2015. These estimates described a small but stable population. Probability of detection remained consistent across years (ranging from 0.51 to 0.53). Breeding density of oystercatchers was higher in southern Oregon. Oystercatcher abundance adjacent to MRs-MPAs accounted for between 12.4–18.3% of the total population estimate, which was lower than expected (approximately 25%). Subsequent conservation efforts for Black Oystercatchers in Oregon could be successful by focusing on limiting human disturbance, particularly on the north and central coasts, and protecting core habitats on the south coast where much of the population resides.

Range-wide monitoring of shorebirds (Aves: Charadriiformes) suggests that many species are declining. For most species, it is unknown whether distinct population units exist, which makes management and conservation difficult. One shorebird of conservation concern, the Buff-breasted Sandpiper (Tryngites subruficollis), is a New World migrant that breeds at Arctic latitudes in North America and Russia and winters in southeastern South America. We conducted a molecular survey of samples representing each of three migratory regions (breeding, migration, and wintering) using nine polymorphic microsatellite loci and 1.5 kb of highly variable mitochondrial DNA (mtDNA) from the cytochrome b gene and mtDNA control region. We analyzed contemporary population structure, demographic trends, and phylogeographic patterns. Overall, microsatellite and mtDNA analyses revealed that Buff-breasted Sandpipers are panmictic both regionally and at a global scale, with no signal of a recent genetic bottleneck. The mtDN...

Counts of Semipalmated Sandpiper (Calidris pusilla) at some migratory stopover sites have shown pronounced declines over the last 35 years. Counts from breeding grounds avoid sources of bias that have proven troublesome for trends estimated from migration surveys. Published and unpublished data were reviewed to examine trends in densities of Semipalmated Sandpipers at breeding sites across Alaska and arctic Canada. Information was sparse, and some comparisons are tenuous because methods varied over time. Valid time series were obtained for 13 sites across the species' range. In Alaska, Semipalmated Sandpipers either increased or were at least stable at six sites and decreased at one site. Surveys at both sites in the central portion of the range suggested no change in abundance. In the eastern portion of the range, trends were variable: decreases were observed at two sites, a possible increase at one site, and no change at another. Thus, the species was generally increasing or stable in the west...