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Cold spring - how did our 2011 migration fare?

Cold weather means birds have to stay at valley bottom before heading upslope

Environment Canada's Chief Meteorologist, David Jones, has declared the spring of 2011 the second coldest (and wettest) on record, as if we didn't already suspect so. Only the 1955-year was worse, and as I recall, it was the time of my first ski touring trip into Garibaldi Park with the Varsity Outdoor Club (UBC) in early May. New powder snow at Garibaldi Lake fell several days before we left in mid-month to catch the train and ferry back to Vancouver in blazing sunshine! This year there was no such break, and the provincial snow data authorities have noted the snow pack to be increasing throughout the spring over the entire southern half of the province. Surely the weather or prolonged snow pack had some impacts on the migratory timing of our avian friends.

Well, the first impact was on our largest bird; in 2010, Mike Gill parked his sleek single-engine Otter at the Green Lake base on March 29. This year his bird had to wait until April 29 before the ice melted off so he could, once again, start his flying season. For the organic birds, there were some similarities.

Although many birds arrived on time, or even ahead of their usual schedule, several had to stay at valley floor level for much longer than normal before proceeding upslope to their usual summer haunts.  Juncos, Golden-crowned and Fox Sparrows, Varied and Hermit Thrushes, and Yellow-rumped Warblers were in that bind. Surprisingly, however, most of the waterfowl tolerated the ice-covered lakes and made do with the small stretches of open water that were around shore edges or on river channels.

Much to our amazement, 157 species were tallied during the spring period with 108 of them being migrants. This is comparable to other years. Waterfowl arrivals were at usual numbers despite the drawbacks, arriving in several waves, the last being after a major storm on May 17th, to bring their total species numbers to 32.  For songbirds, the numbers were mixed - robust for robins, juncos and Yellow-rumped Warblers, average for a few and decidedly sparse for many others. For raptors, game birds, doves and the air-borne sky-divers, numbers are about normal, but shorebirds were decidedly few in number, especially the sandpipers, although Bonaparte's Gulls had two days of big numbers.

Last year, we went through 14 years of data (1997-2010) to calculate an average arrival date for about 130 of our migrant birds. So, how did the timing of the 2011 migration arrivals stack up against the long-term averages? A species was deemed to have arrived on time if it appeared within three days of the calculated average day; that is, our observations have about this much leeway. During spring season, our favoured birding routes (Green Lake Golf Course, Lorimer Road to Rainbow Park) are each traversed two times each week, and on two other days the observations can be elsewhere on the mountains, Shadow Lake, Alpha Lake, Calcheak, etc.  So, here are the surprising results:

• arrival on time (i.e. +/- 3 days): 23 species

• arrival ahead of time, but historically within the window of observations: 39 species

• arrival at unprecedented early date:         8 species

• arrival late but within the window of past observations: 35 species

• arrival very late, latest ever on record: 3 species

• no-shows, but should have arrived in spring: 4 regulars and 31 casuals

"Casuals" are birds not seen every year in the spring season, but it should be noted that 24 other casuals did arrive and are so tallied in the foregoing categories. The four no-shows, which should have passed through, are the Common Tern, Horned Lark, Nashville Warbler and Blue-winged Teal. Three other migrants are expected in June, according to their calculated arrival dates: Cedar Waxwing (June 3), Common Nighthawk (June 6) and Gray Catbird (June 19).

There was one new species addition to the Whistler checklist of birds this spring, a Yellow-breasted Chat at, where else, Toad Hollow. There were also a few other pleasant surprises. On May 10, a rainy day, our first Sandhill Crane (on the ground) was on Fairway No. 11 at Nicklaus North; all previous sightings were flocks of high-flyers. May 12 saw the third ever record of a Red-necked Phalarope on the shoreline of the newly-fenced-in area of the Fitzsimmons fan-delta - the first visitor to take advantage of the enclosure.  Another Red-necked was seen in Shadow Lake, two weeks later. As usual, Toad Hollow had nearly all of the terrestrial birds and coughed up two Anna's Hummingbirds at a feeder, along with hoards of Rufous hummers, and on May 25 it produced Whistler's second-only record of a colourful Lazuli Bunting. There are, however, a few of these buntings along the fence line between Pemberton and Pemberton Meadows each year. And at Shadow Lake (May 27) an exceedingly rare Black and White Warbler popped up in full view.  This is an east-of-the-Rockies species.

So, in the final analysis, the inclement spring may have reduced the volume on a few species of birds, and obviously stalled their movements to timberline, but it did not stymie too many on their usual migration arrival dates. In fact, over one third of the species arrived ahead of time! One may also query as to the timing of mating calls of the resident upland game birds. They were nine to 14 days behind schedule for the Ruffed and Blue (Sooty) Grouse, respectively, but there are no dates for either the Spruce (Franklin's) Grouse or any ptarmigan; neither of the latter two were seen in the spring period. Hopefully, a few more sandpipers and plovers will soon arrive and make use of the fenced-off habitat on Fitzsimmons delta-fan, or fan-delta.