I am curious how snow and or temperature affect the timing of initial arrival and subsequent dispersal of spring staging waterfowl in the sub arctic. Especially for species such as Canada geese, American black ducks, common goldeneye, and greater scaup, when they are near their final breeding grounds but are waiting for the landscape to thaw.
yes, is incredible how the climate parameters influence in the move of birds in general. Also, I think that other important factor and more in the northern part of the world is the cycle light-darkness.
The amount of open water has a lot to do with it. If it is cold enough to freeze lakes and ponds, it forces waterfowl south. If the winter is warm and water stays open, there is not as much movement.
For Greenland White-fronted Geese, which have a double migration, earlier initiation of the first leg is linked to warming temperatures on the wintering grounds http://link.springer.com/article/10.1007%2Fs10750-012-1174-1 but the little information available suggest the timing of the second leg (Iceland - W Greenland) is largely unchanged.
In the estuaries of the Southern Gulf of St. Lawrence the birds come in the fall and will stay as long there is open water. While the following paper relates changes in bird numbers to a decline in eelgrass, bird numbers are now higher than ever in late fall and this is likely a response to the absence of ice.
N R Seymour, A G Miller, D J Garbary (2002) Decline of Canada geese (Branta canadensis) and common goldeneye (Bucephala clangula) associated with a collapse of eelgrass (Zostera marina) in a Nova Scotia estuary HELGOLAND MARINE RESEARCH 56: 3. 198-202 SEP
Hi Keith.
I am no expert in such matters but having read many an account on Bird migration and its weather effects, I would suggest the following. Three factors, to take into consideration, are day-length, moon phases and prevailing wind conditions. Firstly, it goes without saying that day-length is a massive factor in bird migration but it alone simply only accounts for part of to be considered. I find that there are undeniably more events, which come to the fore around both Full Moon and New Moon phases. Lastly, many a study has proven that migrating species often require several days of prevailing Southerly winds to aid their passage. This last comment can apply to both, leaving the wintering area itself and passage from staging areas. For further reference purposes, I highly recommend reading the Bird Migration book by Ian Newton from the New Naturalist Series.
Kind Regards
Tony Powell
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