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Index > Ecological Monitoring > Animal Species >Shorebirds |  |
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Animal Species | Plant Monitoring | Climate Impact on the Ecosystem| Carbon Cycle
animal species
Introduction
Shorebirds
Shorebirds, as their name suggests, are most commonly seen by the shores of oceans, lakes and wetlands. During migration, they are most often seen feeding in large groups on coastal mudflats, or flying in flocks of thousands, weaving patterns in the sky above the sea. Indeed, shorebirds are rarely seen inland, unless you are lucky enough to follow them to their Arctic breeding grounds. In the Arctic, shorebirds form one of the most diverse groups of ground nesting birds, with over 50 species nesting in the arctic regions of the world.
On Bylot Island, the three most abundant nesting shorebirds are Baird’s Sandpiper (Calidris bairdii), White-rumped Sandpiper (Calidris fuscicollis), and American Golden Plover (Pluvialis dominica). Other shorebird species observed nesting on Bylot Island since 2005 include Black-bellied Plover (Pluvialis squatarola), Pectoral Sandpiper (Calidris melanotos), Red Phalarope (Phalaropus fulicaria), Common Ringed Plover (Charadrius hiaticula), and Ruddy Turnstone (Arenaria interpre). However, other shorebird species have been observed on Bylot Island. For a complete list of potential breeders take a look at our bird species list.
MIGRATION
Of all migrating organisms, shorebirds exhibit one of the most impressive migratory strategies. For example, both the White-rumped and Baird’s Sandpipers cover an astounding 15,000 km from wintering areas at the southern tip of South America to their breeding grounds in the Canadian Arctic. At the end of the breeding season, when the young are fully grown (late July through early August), adults and young head south, either inland or along the eastern shores of Canada and the USA. Those migrating inland will often stop for several days at a time to refuel at wetland sites such as the Cheyenne Bottoms in Kansas (one of the largest stopover sites for shorebirds in the interior USA) from late August to early October. Those that choose to migrate along the coast may stop to refuel and rest at the Bay of Fundy, Canada and/or Delaware Bay, USA (the sites of some of the largest concentrations of migrating shorebirds in North America). From sites such as these, shorebirds will head further south, stopping to feed as necessary, until they reach their southerly wintering grounds. This trek may take anywhere from 5 weeks to 2 months. One of the most well known wintering areas for White-rumped Sandpipers is Tierra del Fuego, where thousands of birds can be found feeding along the shorelines from November through March.
POPULATION STATUS
Shorebirds are currently becoming a subject of management concern due to recently documented declining population trends for several species. The factors driving these declines have not yet been confirmed, however, they likely involve loss and/or degradation of habitat at migratory stopover sites and wintering grounds, and climate driven changes occurring on the breeding grounds. Ecological research focussing on non-harvested arctic wildlife, such as shorebirds, is rare. By collecting detailed information on basic ecological parameters on shorebirds, our research is providing information that is essential to determine if current declines are associated with changes in reproductive success on the breeding grounds.
BYLOT ISLAND Bylot Island offers a great opportunity to study factors affecting reproductive success of shorebirds. The abundant glacier valleys provide excellent habitat for shorebirds, in the form of highly productive wetland and mesic tundra . Shorebirds generally arrive in the Qarlikturvik Valley just as the first patches of snow free tundra appear in late May and early June. The first species to arrive are often the Baird’s Sandpipers and the American Golden Plover, generally followed a few days later by the White-rumped Sandpipers. Upon arrival, most birds are caught up in a foraging frenzy in an attempt to rebuild the reserves depleted during their long migration. Early season food resources may be limiting for shorebird reproduction. Food resources may be in short supply as the tundra is still frozen and many areas are still covered in snow. While rebuilding reserves for reproduction, shorebirds must also search for and defend mates, nests and feeding territories. Shorebirds generally lay a clutch of 4 eggs, which hatch in 21 days for sandpipers or 25 days for plovers. The timing of laying is important because shorebirds must synchronize the hatching of eggs with peaks in resource abundance later in the season in order for young to have access to abundant resources (see the insect page for more information).
Though the timing of hatch is critical for the growth and survival of young, even more crucial is the ability of shorebirds to ensure that their nests survive until hatch. Nest predation is an important source of mortality for shorebirds. On Bylot Island, our data indicates that the Arctic Fox is the principal predator of shorebird nests. Shorebird eggs are an alternative prey resource for the Arctic Fox , which preys primarily on small mammal. As is the case with the Greater Snow Goose eggs, predation on shorebird eggs may be higher when the abundance of lemmings is low. Alternately, when lemmings are abundant, the Arctic Fox will focus on lemmings, and shorebirds may experience reduced predation pressure and increased nest success. Shorebird breeding success is known to be linked to lemming cycles via predators at other sites in the Arctic, however, this relationship has yet to be confirmed in for North American populations.
Shorebird research is a recent addition to the ecological monitoring on Bylot Island, having been initiated in 2005. The goals of the shorebird project are primarily to study the effects of climate, food availability and trophic interactions (i.e. predation by Arctic Foxes and avian predators) on shorebird distribution, breeding output and population dynamics.
Our specific objectives are to:
1) Monitor shorebird nests to record nest success and timing of breeding;
2) Record predation events using remote camera systems to identify predators;
3) Sample insects to compare timing of shorebird breeding with insect availability.
To meet these objectives, an intensive survey and monitoring of shorebird nests is conducted each summer. By collecting data on shorebird nesting phenology and success, seasonal abundance of insects, predation pressure (estimated using real and artificial nests), alternative prey abundance (lemmings and geese) and local weather variables, we hope to quantify the relative importance of various environmental factors affecting reproductive success of shorebirds on Bylot Island.
In an attempt to study reproductive success of the same individuals over several years, a sample of shorebirds are banded with unique color coded plastic bands. This shorebird banding program will eventually enable us to estimate annual survival of Bylot Island shorebirds, and potentially re-observe individuals during migration or on the wintering grounds.
RESULTS
Nest Success
Nest success varied greatly from year to year (1% to 80%). Nest success for shorebirds appears to be higher in years when there is a greater abundance of lemmings (i.e. 2007). This trend, however, is only evident for Baird’s and White-rumped Sandpipers.
Nest Predators
All of the predation events that have been recorded at shorebird nests during 2006 and 2007 revealed the Arctic Fox as the nest predator. These photos were taken with Silent Image Reconyx cameras.
Timing of breeding
Egg Laying
Baird’s Sandpipers were among the first to arrive and initiate nests, followed by the White-rumped Sandpipers and the American Golden Plovers. All nests were initiated within a two week period (from 10 June to 22 June). In 2007, birds arrived later than usual and egg laying was delayed in comparison to previous years.
Hatching
Nests hatched within a two week period between 4 July and 20 July. Hatching dates were synchronized with peaks in arthropod abundance in 2005 (14 July) and 2006 (12 July).
