Many passerine species switch to fruit diet in autumn migration as insect
populations decline, even flycatchers, warblers and vireos. Research done out
on Block Island, Rhode Island which examined fecal material from 69 passerine
species and all but one was consuming fruit on the island. The only one that
wasnt, was the Winter Wren. Additional research examined which fruits the
birds preferred and which fruits were best for providing fuel for the migrants
to continue southward. Those species which include fruit in their diets year
round fare better, such as tanagers, finches, sparrows, etc. The insectivores
may have a more difficult time and need more fruit, as fruit is lower in
protein and lipids than insects.
The shrub-carr habitat is often overlooked in Wisconsin as important avian
migration habitat. We are currently analyzing five years of intensive
passerine banding in this habitat from the Westshore of Green Bay. Our habitat
is filled with red osier dogwood (Cornus stolonifera), gray dogwood (C.
cornacea), silky dogwood (C. amomum) , nanny berry (Viburnum lentago),
elderberry (Sambucus canadensis), wild grape (Vitis riparia), Virginia creeper
(Parthenocissus quinquefolia), plus currents and raspberries (Rubus sp.). More
recently we have added glossy buckthorn (Frangula alnus). Ive watched
Phoebes, Wood Pewees, Tree swallows and many warblers and vireos feeding on the
dogwoods, especially the red osier. Flickers, Pileated, Red-bellied, Hairy and
Downy Woodpeckers love the grapes and often becoming tipsy later in the season
as the grapes have been frosted several times and start to ferment.
If you are interested in this diet changeover you can Google; Migrating
Songbirds on Block Island or The Crazy Stuff Birds Eat by Brian Pfeiffer.
There are also several good scientific studies by this group online.
Tom Erdman, Oconto, WI
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________________________________
From: wisbirdn-bounce@xxxxxxxxxxxxx <wisbirdn-bounce@xxxxxxxxxxxxx> on behalf
of Bill Volkert <billvolkert11@xxxxxxxxx>
Sent: Sunday, September 16, 2018 5:24:41 PM
To: Wisconsin Bird Network
Subject: [wisb] Gray Dogwood Berries
I have a number of stands of gray dogwood on our land and one stand just
outside our window. This has always been a magnet for thrushes in
particular, but recently I have had a wide range of species visit these.
It isn't always possible to see if all of the birds that are hoping among
the branches are actually eating the fruit, but I have been able to observe
several picking berries which we may not always expect to be fruit eaters.
This morning I had 2 red-eyed vireos and a yellow-throated vireo picking
dogwood berries and yesterday I saw a Philadelphia vireo eating these as
well. I also watched a blackpoll warbler eating there among a few other
warbler species and have sighted several other warblers among the bushes
which I cannot verify whether they are just perching there, eating insects
or actually taking fruit. In the past I have also seen eastern phoebe
eating berries, but we lost our nesting pair during the spring snowstorm.
At this time the shrubs are now nearly stripped clean of most berries so
they doesn't last too long but are definitely sought after, and the birds
provide the service of dispersing the seeds.
If anyone is looking for a good shrub for cover and fruit I would recommend
gray dogwood among other native varieties. They will need some room as
they can develop a dense cluster and tend to spread over time, but that
just means more bird habitat.
Bill Volkert
FdL Co
--
Bill Volkert
Naturalist
www.billvolkert<http://www.billvolkert>
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