Arenaria Melanocephala Research Articles

Alaska’s climate sensitive Yukon–Kuskokwim Delta supports seven million Arctic-breeding shorebirds, including the majority of six North American populations

Abstract Baseline information about declining North American shorebird populations is essential to determine the effects of global warming at low-lying coastal areas of the Arctic and subarctic, where numerous taxa breed, and to assess population recovery throughout their range. We estimated population sizes on the Yukon–Kuskokwim Delta (YKD) in western Alaska on the eastern edge of the Bering Sea. We conducted ground-based surveys during 2015 and 2016 at 589 randomly selected plots from an area of 35,769 km2. We used stratified random sampling in 8 physiographic strata and corrected population estimates using detection ratios derived from double sampling on a subset of plots. We detected 11,110 breeding individuals of 21 taxa. Western Sandpiper (Calidris mauri), Red-necked Phalarope (Phalaropus lobatus), Dunlin (subspecies C. alpina pacifica), and Wilson’s Snipe (Gallinago delicata) were the most abundant taxa. We estimated that ~7 million individual shorebirds were breeding on the entire YKD in 2015 and 2016. Our surveys of this region provided robust population estimates (coefficient of variations ≤ 0.35) for 14 species. Our results indicate that the YKD supports a large proportion of North America’s breeding populations of the Pacific Golden-Plover (Pluvialis fulva), the western population of a Whimbrel subspecies (Numenius phaeopus hudsonicus), a Bar-tailed Godwit subspecies (Limosa lapponica baueri), Black Turnstone (Arenaria melanocephala), a Dunlin subspecies (C. alpina pacifica), and Western Sandpiper. Our study highlights the importance of breeding shorebirds of this relatively pristine but climatically sensitive deltaic system. Estuaries and deltaic systems worldwide are rapidly being degraded by anthropogenic activities. Our population estimates can be used to refine prior North American population estimates, determine the effects of global warming, and evaluate conservation success by measuring population change over time.

Using Geolocator Data to Address Changes in Migration Patterns for Black Turnstone

AbstractBlack Turnstone is an obligate Pacific coast shorebird that is included as a “Species of High Concern” in both the U.S. and Alaska Shorebird Conservation Plans. Specific migration routes for this species are not well understood, which makes its recent disappearance at a major spring stopover site, northern Montague Island in Prince William Sound, Alaska, difficult to interpret. We tracked 23 Black Turnstones between breeding and wintering areas and examined migration timing, duration, and routes used. We identified two high-use regions during migration: 1) Cook Inlet/Shelikof Strait, Alaska, and 2) the Haida Gwaii Archipelago in British Columbia/Alexander Archipelago in southeastern Alaska. This second region was also an important wintering area. We found that northbound migration was longer than southbound (the reverse of what is often observed in shorebirds) and that staging behavior was primarily seen during northbound migration. No birds were tracked to northern Montague Island, and only a few individuals stopped anywhere in Prince William Sound. Alterations in patterns of spring herring spawn in Prince William Sound may be affecting the routes and stopovers used by Black Turnstones, and birds may be wintering farther north in recent decades due to warmer winter conditions. Additionally, the increasing availability and popularity of citizen science efforts like eBird has created a mechanism for disseminating observations from less accessible parts of the Black Turnstone range, a fact which may confound our understanding of whether migration routes for this species have changed over the last 30 years.

HELMINTH COMMUNITIES OF THREE SYMPATRIC SPECIES OF SHOREBIRDS (CHARADRII) FROM FOUR SUMMER SEASONS AT BRISTOL BAY, ALASKA

Helminth communities in sympatric black turnstones (Arenaria melanocephala), ruddy turnstones (Arenaria interpres), and dunlin (Calidris alpina) were examined over 4 summers in Bristol Bay, Alaska. The compound community, made up of component communities of all 3 species of hosts for 4 summer seasons (n=164), consisted of 43 helminth species, with cestodes, especially Anomotaenia clavigera, accounting for 47% of the helminth species and 95% of the abundance. The black turnstone had significantly higher species richness and abundance than either the ruddy turnstone or dunlin. The congeneric black and ruddy turnstone component communities were the most similar, and the dunlin's was the least similar. New helminth species continued to be acquired in all 3 host species during years 2 to 4. There was no significant difference for abundance among sample years for each of the 3 species of host. The 3 component communities all included a predictable suite of helminths with 1 dominant species and 4 to 5 associates, a large number of less-predictable species, and a greater prevalence and abundance of cestode species. Consistencies over time included high diversity, low evenness, low species richness (<5), and continued recruitment of small numbers of helminth species with low prevalence and abundance. There was minimal circulation of helminth species between the dunlin and the 2 turnstone species, indicating a considerable degree of specialization, particularly among species of cestodes.

Predation on Pacific herring (Clupea pallasi) spawn by birds in Prince William Sound, Alaska

AbstractWe examined bird diets in areas with Pacific herring (Clupea pallasi) spawn at northern Montague Island in Prince William Sound, Alaska. Diets of the five most abundant bird species consisted primarily of herring spawn. Using a bioenergetics model, we estimated that in spring 1994 the five‐bird species ate 857.1 metric tons (mt), representing 31% of the estimated spawn deposition. The two most numerous consumers, glaucous‐winged gull (Larus glaucescens) and mew gull (Larus canus) consumed 26% and 3%, respectively, of the estimated spawn deposition. Surf scoters (Melanitta perspicillata), surfbirds (Aphriza virgata), and black turnstone (Arenaria melanocephala) together consumed 2% of the spawn deposition. In years with low spawn biomass, such as 1994, the number of herring larvae produced could be significantly affected by normal rates of avian predation. The high consumption by gulls, shorebirds, and surf scoters underscores the importance of herring spawn in the annual cycle of these species and requires further investigation.

Mate fidelity and breeding site tenacity in a monogamous sandpiper, the black turnstone

We examined the relationship between mate fidelity and breeding site tenacity during a 5-year study of the black turnstone, Arenaria melanocephala, a socially monogamous sandpiper breeding in subArctic Alaska. We tested the predictions of several hypotheses regarding the incidence of divorce and the benefits of fidelity to mate and breeding site. Interannual return rates to the breeding grounds (88% for males, 79% for females) were among the highest yet recorded for any scolopacid sandpiper, and 88% of returning birds nested on their previous year's territory. The annual divorce rate was only 11%, and mate fidelity was significantly linked to fidelity to territory but independent of sex and year. Males arrived in spring significantly earlier than their mates and interannual fidelity was influenced by the relative timing of arrival of pair members. Reunited pairs had significantly higher fledging success than new pairs formed after death or divorce. The incidence of divorce was unrelated to reproductive success the previous year, although birds nested significantly further away after failure than after a successful nesting attempt. Sightings of marked individuals suggested that members of pairs do not winter together, and breeding site tenacity provides a mechanism through which pair members can reunite. We reject the ‘incompatibility’ hypothesis for divorce in turnstones, and our data contradict predictions of the ‘better option’ hypothesis. Alternatively, we propose the ‘bet-hedging’ hypothesis to explain the occurrence of divorce, which transpires when an individual pairs with a new mate to avoid the cost of waiting for a previous mate to return. Such costs can include remaining unmated, if the former mate has died, or experiencing lower reproductive success because of delayed breeding.

Host and geographic distribution of Skrjabinoclava spp. (Nematoda: Acuarioidea) in Nearctic shorebirds (Aves: Charadriiformes), and evidence for transmission in marine habitats in staging and wintering areas

Twelve species of shorebirds belonging to the families Charadriidae (N = 3) and Scolopacidae (N = 9) were infected with 11 species of Skrjabinoclava and there was little overlap of parasites between these two families of birds. Most Skrjabinoclava spp. are transmitted apparently in marine staging and (or) wintering areas of their hosts, as indicated by the presence of larval stages of six species. There was no evidence that transmission occurs on the breeding grounds in freshwater habitats. Skrjabinoclava tupacincai, found predominantly in sanderlings (Calidris alba (Pallas)), is transmitted on the Pacific (Washington, California, Chile) and Atlantic coasts (New Jersey) in winter and the Gulf of Mexico (Florida and Texas) in winter and spring. Skrjabinoclava myersi was found, with a single exception, only in sanderlings, and transmission is apparently restricted to coastal Washington and California in winter. Skrjabinoclava bakeri, found predominantly in western sandpipers (Calidris mauri Cabanis), is transmitted on the Pacific coast (California) and in the Gulf of Mexico in winter. Skrjabinoclava morrisoni and Skrjabinoclava pusillae were found mainly in semipalmated sandpipers (Calidrispusilla (L.)). Both parasites are transmitted in the Gulf of Mexico in spring, but S. morrisoni is also transmitted in the Bay of Fundy in fall. Skrjabinoclava inornatae, found mainly in willets (Catoptrophorus semipalmatus (Gmelin)), is transmitted in Louisiana, Texas, and Peru in winter. Skrjabinoclava kritscheri was found only in marbled godwits (Limosafedoa (L.)), and it is suggested that infected birds collected in southern Alberta in spring acquired their infections while wintering along the Pacific coast of the United States. Skrjabinoclava hartwichi, found in black turnstones (Arenaria melanocephala (Vigors)) wintering in California and ruddy turnstones (Arenaria interpres (L.)) wintering in Peru, is transmitted along the Pacific coast of North America. Skrjabinoclava semipalmatae was found in semipalmated plovers (Charadrius semipalmatus Bonaparte) wintering in California. Skrjabinoclava wilsoniae was found in Wilson's plover (Charadrius wilsonia Ord) wintering in Texas and in a black-bellied plover (Pluvialis squatarola (L.)) migrating through southern Alberta in spring. Skrjabinoclava bartlettae was found in black-bellied plovers collected in southern Alberta in spring and Louisiana in winter.

The Importance of Subarctic Intertidal Habitats to Shorebirds: A Study of the Central Yukon-Kuskokwim Delta, Alaska

A 6-year study of shorebird use of intertidal habitats of the Yukon-Kuskokwim Delta revealed this area to be one of the premiere sites for shorebirds throughout the Holarctic and worthy of designation as a Hemispheric Shorebird Reserve in the Western Hemisphere Shorebird Reserve Network. The study area, which covered 10% (300 km2) of the delta's intertidal flats, regularly hosted 17 species of shorebirds between late April and mid-October. The greatest use was during the postbreeding period (late June-October), when Dunlins (Calidris alpina), Western Sandpipers (C. mauri), and Rock Sandpipers (C. ptilocnemis), each with large local nesting populations, accounted for 95% of the shorebirds recorded. Peak counts during autumn approached 300,000 birds. Considering the seasonal occurrence and turnover of populations, we estimate 1-2 million shorebirds use the central delta each year. The delta supports large fractions of the Pacific Rim or world populations of Bar-tailed Godwits (Limosa lapponica), Black Turnstones (Arenaria melanocephala), Red Knots (C. canutus), Western Sandpipers, Dunlins, and Rock Sandpipers. Densities of shorebirds using the central delta's four major bays and connecting coastal areas peaked at 950 shorebirds/km2 in early September. Hazen Bay frequently hosted more than 1,200 shorebirds/km2. Postbreeding shorebirds used intertidal habitats in three distinct patterns according to age class. For most species (n = 7), there was a period when adults appeared first, followed by a brief interval when adults and juveniles mixed, then by a prolonged period when only juveniles remained. In the second pattern (n = 3 species), adults moved onto the intertidal flats first, were later joined by juveniles for a prolonged staging period, then migrated with them. In the third pattern (n = 3 species), only juveniles used the delta's intertidal habitat. Temporal segregation among species and age groups may minimize competition for food and thereby allow the delta to support high diversity and numbers of shorebirds.

Impact of avian predators on high intertidal limpet populations

Black turnstones ( Arenaria melanocephala (Vigors)), black oystercatchers ( Haematopus bachmani Audubon), and gulls of the western/glaucous-winged complex ( L. occidentalis Audubon and Larus glaucescens Naumann) were observed to feed on limpets ( Collisella spp.) in the high intertidal zone on the coast of Oregon, U.S.A. Black turnstones were the major predators of small limpets (< 10 mm), whereas oystercatchers were the major predators of large limpets (> 20 mm). Intermediate-sized limpets were eaten by all of these species. Visitation by avian predators to marked plots was infrequent; but, in the case of turnstones, the cumulative time spent foraging by a visiting flock was sometimes substantial. Two bird-exclusion experiments in the high intertidal zone indicated that birds decreased densities of 5–10 mm limpets ( Collisella spp.), but not densities of smaller limpets. The effects of avian predation on large limpets (> 10mm in length) could not be tested because the latter were rare on exposed high intertidal mudstone beaches. An experiment in which 6–10 mm limpets were added to caged and uncaged plots demonstrated that avian predators (probably turnstones) were capable of drastically reducing limpet densities in unvegetated high intertidal areas. A second trial, conducted 10 wk later, showed no evidence of avian predation suggesting that avian predation varied temporally.

Dichoanotaenia multifilamenta sp. n. (Cestoda: Dilepididae) from the Black Turnstone, Arenaria melanocephala (Vigors), in Alaska

Dichoanotaenia multifilamenta sp. n. (Cestoda: Dilepididae) from the Black Turnstone, Arenaria melanocephala (Vigors), in Alaska is described. This cestode is distinguished from other species of the genus Dichoanotaenia López-Neyra 1944 mainly by the structure of the cirrus and of the egg.

Hunting Tactics of a Peregrine Falcon on Black Turnstones

Hunting Tactics of a Peregrine Falcon on Black Turnstones

Charles Edward Howard Aiken

tocottus armatus) in large numbers. These semi-transparent fry, less than an inch long, were eaten by several species of waders. Other parts of the riverside, comprising stretches of clay, sand or gravel and producing less animal life, were not used to any extent except by Greater Yellow-legs (Totanus melanoleucus) and the scarce Wandering Tattler (Heteroscelus incanus). The most abundant species were Red-backed Sandpiper, Least Sandpiper (Pisobia minutilla) and Western Sandpiper. This area, more than any other, was frequented by Western Dowitchers, and these were the tamest of all the waders so that it was usually possible to walk within a few yards of where they stood before an alarm was given. One or more Greater Yellow-legs were seen here frequently, and at least two of these remained after the migration was over. Food.-Analyses of the stomach contents of waders taken at Tlell showed that Black Turnstones had fed exclusively on barnacles and gastropods, which also were the chief food of Aleutian Sandpipers plus a small number of limpets, blue mussels, amphipods and a small nereid. The food of Sanderlings was entirely crustacean, comprising amphipods, isopods and mysids. Sculpin fry had been eaten by a Greater Yellow-legs, a Wandering Tattler and two Western Dowitchers. The food of Redbacked Sandpipers was the amphipod Corophium spinicorne exclusively, except in one instance where a small polychaete had been eaten. A Hudsonian Curlew had fed upon amphipods and a shore crab (Hemigrapsus sp.); a Semipalmated upon ground beetles and an amphipod, and a Least Sandpiper on larvae of Diptera and Coleoptera. The material found in Western Dowitchers comprised gastropods, polychaetes, sculpin fry and larvae of Diptera and Coleoptera. A Black-bellied Plover had taken 8 small clams (Macoma sp.), gastropods, amphipods, 1 mysid, 2 isopods and a small fish.