Posted by: Anne Murray | October 4, 2010

Counting shorebirds

Long-billed Dowitchers at Reifel Bird Sanctuary, Delta, BC

Fall is a great time for shorebird watching around the Fraser delta.  On a recent visit to Reifel Bird Sanctuary at high tide our birding group was rewarded with impressive close-up views of hundreds of Long-billed Dowitchers.  They were feeding so intensely that they didn’t startle on our approach or even when a lively bunch of elementary school children arrived.

I was interested in estimating the number, which I guessed originally as being several thousand. However, I knew that estimations can be wildly off if one is inexperienced, so I decided to work it out more systematically.  I took some photos from up the viewing tower and printed them out. Then I circled each bird as I tallied them up, to make sure I only counted them once.  The birds were all standing slightly apart as they fed, so there was surprisingly little overlap.  It was a very still, calm day, so each bird cast a shadow, giving the appearance of twice as many birds. Off in the distance more birds spread out and these could only be roughly counted.

The big flock of Long-billed Dowitchers from above

My tally came to 591 birds in the large foreground flock with perhaps another 100 off in the distance, for a grand total of about 700 birds – not the thousands I had guessed, but a large number of dowitchers.

We looked at the birds carefully through binoculars and a telescope, and their plumages ranged from adult to juveniles.  They called quietly to each other as they fed.  As far as I could tell they were all Long-billeds, though of course you cannot tell by the length of bill.  I checked out the plumage variations in Sibley’s field guide and that, and the call notes, helped distinguish them.

A young Peregrine Falcon came down and harassed them repeatedly but failed to catch one.  The dowitchers flew up once, but quickly settled again – they must have been extremely hungry and were taking advantage of the good tidal conditions in the lagoon.

Anne Murray



  1. Russ Cannings visited Reifel the day after us and he reported on BCVANBIRDS seeing 3000 Dowitchers there. At least I think thay’s the number he reported. A long time ago I was taught how to use a grid system to count large flocks, but I got old, and I forget the method. Cheers: Tom

  2. That is certainly the best way! My guestimate of 3000 was based on counting the birds in a small area – then projecting a”grid” in my mind and counting the grids then multiplying by the grid number – then adding the extra ones further down.

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