Naturespeak

Autumn Migration, 2003

Early Departures and Unseasonal Interruptions

Whistler Naturalists

The autumn migration was unusual, to say the least. Up to Thanksgiving the bird counts were normal or above average on some species. But after the flood the numbers were reduced to a trickle, with many species seen rarely thereafter.

Compounding the low numbers during the period were the out migration of many of the song bird species (flycatchers, swallows, vireos and warblers) and our breeding ospreys before the onset of autumn (Sept. 22). Was their departure on advanced warning that a strange autumn was in store?

The mid-October flood, followed by the early November cold snap rudely interrupted the migration of waterfowl, and sent many of the lingering smaller birds on their way. Of the 154 autumn registered species on the Checklist of Whistler Birds only 89 (or 58 per cent) were spotted over the season.

But there were a few surprises; another six unseasonal species were seen including: a Greater white-fronted goose who hung around with a large flock of Canada geese for several weeks, Mew and Western gulls, Bohemian waxwings, a Northern shrike, and an American goldfinch. This brings the amended autumn list up to 176 species, i.e. 16 others added in 1996 to 2002, and hence a revised recovery of 54 per cent – definitely on the low side.

What were the missing species?

Of the waterfowl, including the coots, one third of the normally expected migrants failed to show, although all grebes, loons and geese species did appear. The absence of many of the duck species may be due to a murky Green Lake which, at the time of writing, is still discharging muddy water into the Green River (see Pique Nov. 28, 2003). However, the Trumpeter swans arrived on cue in early November, although all disappeared the day after the Christmas Bird Count!

Raptors and game birds, sparse as always, were seen at irregular intervals with only the Sharp-shinned hawk and Willow ptarmigan missing. The White-tailed ptarmigan, however, was spotted several times and the highlight was a flock of eight or nine in Bagel Bowl on Dec. 12 ^th . Rails and shorebird species were also sparse; a few days of Long-billed dowitcher sightings before the flood and coots up to the Christmas Bird Count was it, and the last coot was knocked off by an aggressive hawk before the eyes of those living at Adventure West. Large gulls flourished at the land fill, but two of the smaller species, which are migrants, Bonaparte and Ring-billed, were not seen.

Of the species inhabiting the forest there was not one audible "coo" or "hoo" from a Band-tailed pigeon and, aside from the uprising of Pygmy owls on the Christmas count, the only other owl sighting was a Barred seen by Jim Wharin in his bike rides on the trail A River Runs Through It. Woodpeckers were generally scarce, even the flicker on some days, because there was easy pine beetle fare in the infected forests to the north of Whistler. That is the going explanation for the time being. We never did spot a Red-breasted sapsucker or a Three-toed woodpecker, which are always hard to find, beetle invasion or not.

All species of jays, crows and chickadees were seen and the numbers were about normal. Robins flocked up in early October but few have been seen after the flood. Colourful Varied thrushes have been sparingly sighted throughout the season and the Christmas count had a record high seven individuals. While the Cedar waxwings departed the valley in late summer, their brethren, the rarely seen Bohemian waxwing, moved in early and modest-sized flocks have been recorded throughout the Sea to Sky corridor. In many years they are not seen at all because their usual range is on the east side of the province, or father east.

For the birds of the bush land, most of the sparrow species have been present, although only the Song sparrow on a consistent basis. There were no sightings at all of the Golden-crowned sparrows and Western Tanagers which were last seen in late summer. Snow buntings from the north also failed to show up, although they are on the Fraser delta. We do have blackbirds, both of our usual species, but the Brown-headed cowbird left ahead of schedule, and the very rarely seen Western meadowlark did show up at Nicklaus North.

From the early signs it looked like a tough season for finches, and even the House finch was becoming hard to find after the flood. But with the arrival of snow in mid-October, the tide has changed. Pine siskins arrived in record numbers and there have been many alpine/subalpine sightings of Purple finches, crossbills and Pine grosbeaks after several years of scant observations. This "invasion" is widespread to at least as far east as Duffey Lake. However, we have not seen any Common redpolls among the siskins, and the biggest mystery is the disappearance again of the Evening grosbeaks – a regional phenomenon bucked only by the flocks at D’Arcy which numbered 87 birds on the Christmas Bird Count.

Another oddity of the season was a Pacific loon on a golf course pond at Nicklaus North, after the flood. This is a first record of any species of loon on a pond at Whistler; their habitat is the middle of our larger lakes.

For 2004 the Whistler Naturalists will follow the lead adopted elsewhere for the definition of seasonal dates for birds. Seasons will begin on the first day of the month and not the 21 ^st or 22 ^nd . So autumn next year is Sept. 1 ^st to Nov. 30 ^th , in tune with the biological clocks of the birds, and Christmas bird counts will always be in winter now defined as Dec. 1 ^st to Feb. 28 ^th or 29 ^th . The four volume tomes of Birds of British Columbia uses these seasonal definitions and our Whistler Bird Checklist will be revised accordingly.