For the past five days I have had a Wood Thrush singing in the woods that
surround our house. This is an uncommon migrant on our land and there is a
scattered population of wood thrushes that nest in the northern Kettle
Moraine nearby. However, I have noticed this several times over the years
that birds that stopped over on our land in spring will appear again for a
while in late June or early July.
I also have had a Yellow-throated Vireo singing regularly who arrived
recently and on Monday and Tuesday I had a Virginia Rail calling from the
small wetland below our house. There seems to be a local movement among
some individual birds in early summer as noted by these arrivals. No doubt
there are probably a number of explanations for this summer shuffle of
birds.
Perhaps these are unsuccessful males that move around in hopes of still
finding a mate. Prime territories have been claimed for the summer, so
these could be first-year males that are moving about still hoping to find
a place for themselves.
It could also be that these are birds that have already nested and raised a
family, although there is plenty of time for a second brood or nesting
attempt if the first one failed. I would expect that birds with a
territory in prime habitat would stay there rather than leave to find
something else.
Or maybe there is the loss of a mate and these bird have abandoned their
territory in search of a more secure territory. However, my guess is that
most of these are likely floaters, or unsuccessful males that are trying
their luck as they move about and will probably have to wait until next
year to try again.
With the concern over long-distance migrants and the many hazards they face
these days, it is compounded by the fact that many first-year males are not
able to compete for prime territory or do not find a mate even if they are
able to reproduce. Most of our warblers have rather distinctive first-year
plumages, which are best seen in the hand when banding them. The most
obvious is the American Redstart which looks much like the female in its
first year and doesn't attain the adult plumage until its second year. So
survival for these birds is essential not to only make it from one year to
the next, but also to live at least two to three years in hopes of
successfully reproducing and adding enough young to the population to
replace those that are lost each year.
These are thoughts that ran through my mind as I listened to the wood
thrush. While it has a most beautiful song, this one will likely have to
wait until next year, and hopefully survive another amazing journey, before
it has a better chance of nesting.
Bill
Fond du Lac County
--
Bill Volkert
Naturalist
www.billvolkert
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