WEll here's a guess, the mergansers observed are indeed migrants from
either the interior or from farther south and have arrived in
anticipation of the herring spawn. The flock is largely composed of males
because they migrate earlier.

Or, this flock is of migrants that have arrived early and have not timed
their arrival for the spawn (since it occurs later) and may or may not
partake in the local feast.

Or, this flock is of 'forced' migrants because the local wintering lake
or river has become too silty from the spring run-off. And these birds
have merely relocated to more suitable waters.

THese are some possible scenarios, at least I think they are possible,
perhaps others may feel differently.

cheers,
Don Cecile
dcecile at cln.etc.bc.ca


On Sun, 18 Feb 1996, Michael Price
wrote:

> On Feb 14, Karen Irving and Duncan McLellan saw a tight flock of 60 Common
> Mergansers, all alternate-plumaged males except for four females, on the
> Fraser River at Deas Island Regional Park in South Delta. As it's awfully
> early for the herring and oolichan runs, each several weeks away, and
> usually waterfowl and seabirds that pile in here for those runs don't
> usually migrate until they're over, has anyone any guesses for a) such a
> large concentration and b) such a heavy male presence (obligatory bonding
> joke here)? Inland bodies of water were ice-free at the time.