Posted on: May 28, 2015
Author: Stephen Brown
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With several days of surveys completed, we are seeing first-hand the diversity and abundance of shorebirds and the range of habitats in the Yukon Delta National Wildlife Refuge.
By far the highest densities of shorebirds are along the coast, which is consistent with previous smaller studies conducted by our colleagues Brian McCaffrey, Bob Gill, and others. Where our crew is working, the coastal area in the far north near the tiny native village of Kotlik and along the coast between the villages of Emmonak and Scammon Bay, has been literally hopping with shorebirds and waterfowl. We expect that the coastal crew will observe the highest densities of shorebirds when they start working later this week by boat and float plane in the central coastal region that comprises the delta between the Kuskokwim and Yukon rivers.
What does a rapid surveyor see in a high density region? Thus far, on a 40 acre plot in an hour and a half, our data shows as many as 77 individuals, of which as many as 22 nesting pairs appear to be using that plot. From PRISM surveys over the past couple of decades, we know that on a species rich plot the surveyor will, on average, observe about 80% of the birds that are actually nesting on that plot. So we know that these regions are probably even more productive for shorebirds than they appear from our raw counts.
On one plot that was primarily foraging rather than nesting habitat, Brad Winn observed 95 birds feeding—61 Pectoral Sandpipers, 21 Long-billed Dowitchers, 11 Red-necked Phalaropes, and two Dunlin. On another plot, Bob observed 14 pairs of Dunlins!
One of the greatest joys of being on the tundra is the opportunity to observe the breeding behaviors of these species. Male Western Sandpipers, like their cousins Semipalmated Sandpipers, fly incredibly tight aerial displays side by side as they establish the boundaries of their territories. This behavior is one of the best clues we can use to determine if there are pairs of Westerns nesting on that plot, along with the characteristic buzzy calls made over the territories. Another clue is when we flush a bird off a nest and she does a “mouse crawl” where she squeaks and fluffs up her feathers while hunkering close to the ground and trying to lure us away from the nest. On one occasion, we saw a Black-bellied Plover defend its territory by mobbing a Glaucous Gull—she hastily departed under the barrage.
For those of you who enjoy lists, here are the 21 species of shorebirds that our crew has documented on their plots so far: Black and Ruddy Turnstone; Rock Sandpiper; Western, Least, Pectoral and Semipalmated Sandpiper; Hudsonian and Bar-tailed Godwit; Whimbrel; Pacific Golden, American Golden, and Black-bellied Plover; Greater and Lesser Yellowlegs; Wilson’s Snipe; Red and Red-necked Phalarope; Long-billed and Short-billed Dowitcher; and Dunlin. In addition, we’ve seen a couple of Bristle-thighed Curlew from the helicopter in the upland regions of the refuge where Bob Gill and Brad Winn have both done surveys in the past.
We have more surveys to do yet, so check back to hear how they turn out, along with an update on what life is like in camp.