[texbirds-freelists] [texbirds] Progeso sod fields (Cameron Co.) on 04/26/12

From: Rex Stanford <calidris@xxxxxxxxxxxxxx>
To: texbirds@xxxxxxxxxxxxxxxxxx
Date: Thu, 26 Apr 2012 23:18:07 -0500
Today (04/26/12) in late afternoon we birded the Progreso sod fields,
focusing on shorebirds, including "grasspipers." The results were
disappointing in terms of numbers of species, but we enjoyed observing some
bird behavior at this site.

The shorebird species seen were: UPLAND SANDPIPER (1, in field west of
north/south traversal road); and in the field at the northeast end of the
traversal road (i.e., just before the levee and on one's right as one heads
north) were LESSER YELLOWLEGS (est. 30-35); GREATER YELLOWLEGS (est. 6-8);
PECTORAL SANDPIPER (est. 15-17); LEAST SANDPIPER (est. 10-12); BLACK-NECKED
STILT (est. 8-10); and WILSON'S PHALAROPE (2, minimal or no bright
plumage--males or nonbreeders). MOTTLED DUCK was present in small numbers
and HORNED LARK (1).

Although the diversity of species was decidedly disappointing, we found
fascinating certain avian behavior at the field where all but one of the
shorebird species was found:

1. A fierce, wind was gusting out of the south/southeast, so strong that
both of us were nearly blown about (or over) more than once, almost enough
to make us break off our observation.  We constantly feared that our tripod
with scope atop it would be toppled. Interestingly, it seemed as though the
foraging shorebirds all had anticipated the most efficient way to forage the
entire width (north/south) of this sod field. When we arrived at the field,
almost all were near the north west corner of this field, actively feeding.
They then proceeded southward across the field, foraging all the time.  We
studied them for quite a while, and by the time we left, they had moved to
very near the south side of the field. Given that birds regularly try to
face into a strong wind in order not to have their feathers disturbed,
ruffled, or even, perhaps, damaged, they had to forage southward due to the
wind direction. What we found interesting was that the birds had flown into
the northwest corner of the field, thereby enabling unruffled foraging
across the entire width of the field and obviating the need or flying back
north of, beyond, previously foraged areas to get to unforaged terrain in
this field (and obviating the need to do so repeatedly). We are not
suggesting that we observed anything usual in this behavior, rather that it
seemed that in some sense these several species anticipated, given the stiff
and gusty wind, the best way to forage the entire width of the field with
the least problems and waste of effort.

2. There were some agonistic (i.e., socially hostile defensive behavior)
interactions between some of the yellowlegs. They appeared to have developed
from perceived intrusions into feeding territory by a member of the same
species. What was entertaining here was the behavior of a Wilson's Phalarope
who was caught right in the middle of one of the spats. One yellowlegs took
flight, right over the phalarope, attacking the other that had been
approaching its feeding area, and then a mid-air attack occurred right over
the head of the phalarope, who simply pulled in its neck, did a bit of a
squat, and coolly walked forward a few steps, never attempting to take
flight itself or really flee, despite the overhead ruckus. It was fun to
watch, and we fancied we might have seen a "Well, here they go again!"
reaction.on the part of the cool-headed phalarope.

It was fascinating to watch these behaviors, and the first instance, at
least, seemed to tell us something about the intelligence--be it learned,
instinctual, or perhaps a combination of both--of these birds' foraging
behavior. Food for thought!

Wishing everyone rewarding spring-migration birding,
Rex and Birgit Stanford
McAllen, TX

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[texbirds-freelists] [texbirds] Progeso sod fields (Cameron Co.) on 04/26/12

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