A Northwoods Almanac for July 20 – August
2, 2012 by John Bates
Sightings: Gray Fox, Bobcats in
Birdbaths, Red-bellied Woodpeckers, Owls . . .
Jim Ferguson
on Lake Tomahawk noted that a family of Baltimore orioles have appeared at
their feeders. He also noted that only four loon chicks have been
reportedly seen on all of Tomahawk Lake.
Most
remarkably, he passed on a sighting from a friend in Memphis, Tennessee: “After
I told him how hot it had been here, he replied that it was nothing compared to
Memphis. He had recently looked out his window and saw a bobcat
sitting in his birdbath. No doubt it had a happy expression!”
Linda Thomas in Sayner reported that she has been feeding a red-bellied
woodpecker for a few weeks, and she has a pair of evening grosbeaks utilizing
her bird bath. She also noted that “there is still at least one albino crow on
the Plum Lake
Golf Course.”
Kristi Wehrwe inWoodruff had
been watching a male gray fox in her yard in Woodruff for several weeks, and
now she has seen the male and female walking together down her
driveway. Kristi noted that the male was “good-sized, healthy and
surprisingly beautiful.”
Larry Leal sent me a few pictures of scarlet tanagers that are likely
nesting near his home, and which frequently take a bath in his pond. Larry also
had a barred owl nest in a tree right by his house this spring. He set up a
camcorder and taped the young owls as they grew. He noted: “We saw the parents
all the time bringing chipmunks and other goodies to the tree . . . We still
see all three of them around the house . . . We have been here 22 years and
always had owls here . . . When I sit behind the house in the fall bow
hunting, one of the owls always flies by and sits in a tree by me.”
Cowbirds
John
and Karin Randolph in Hazelhurst sent me a note saying they “were not enthusiastic
to see a female Baltimore oriole feeding some grape jelly to a male
brown-headed cowbird juvenile on the railing of our deck this afternoon
(7/15).” John noted, “I've heard
that there are some cowbird control measures that have been taken in areas where
it is hoped to strengthen Kirtland warbler populations, and I don't know for
sure whether cowbirds are considered otherwise protected songbirds in
Wisconsin, or are exempted from protection. Anyway, we would rather see
more orioles next year than cowbirds. On the other hand, we would feel
better if researchers have shown that, for the most part, the parasitic
behavior of cowbirds doesn't have a material adverse affect on songbirds in
general.”
Unfortunately
though cowbirds are a native species and belong here as
much as a robin or song sparrow, they can clearly
impact various populations of songbirds, and thus they raise the ire of nearly
everyone who loves birds. Cowbirds are a brood parasite, meaning they lay their
eggs in the nests of other birds. And not just a few birds, but more than 300
species. Cowbird hosts range in size from tiny brown creepers, kinglets, or
gnatcatchers to far larger meadowlarks.
The
cowbird female not only lays eggs daily in other birds’ nests, she generally
removes one or two of the host’s eggs, though seldom all of them, after laying
her own. For years, researchers wondered why the cowbird wouldn’t reduce the
competition to zero by removing all the eggs, but a recent study appears to
have answered this question by examining cowbird young in eastern phoebe nests.
In this study, cowbird young that shared the nest with two phoebe young grew
faster than cowbirds that were alone in the nest. The reason was that the
parents brought food to the nest with three young more often than to a nest
with one young – there were more mouths to feed! The cowbird chick was better
at begging, so it got a greater proportion of the food than the two phoebes.
The researchers concluded, “In other words, cowbirds exploit the begging of
their foster siblings to get more food than if they were alone!”
There
is no question that cowbirds can adversely affect their host populations,
though the effect is variable. For instance, relatively large birds, or those
that produce many broods, like red-winged blackbirds and song sparrows, are
usually successful at raising a number of their own young along with a cowbird,
thus dampening the overall effect of parasitism on the population.
For
smaller species with longer incubation times than cowbirds, such as vireos and
many flycatchers, a single cowbird egg can result in total loss of reproduction
for a nesting pair. Since the cowbird egg hatches first and the females will
stop incubating to feed the chick, their own eggs rarely hatch. Thus, these
populations can come under great threat if cowbird parasitism is frequent.
Many
species have evolved to fight back. Some species respond to strange eggs in
their nest by rejecting the cowbird egg. This rejection is done by either
(1) ejecting cowbird eggs – American
robins, gray catbirds, kingbirds, blue jays, brown thrashers, cedar waxwings,
and northern orioles almost always (> 88% of the time) reject cowbird eggs
(2) burying cowbird egg(s) and
occasionally their own under a new nest lining – yellow warblers
(3) deserting the nest with the cowbird
egg
Cowbirds prefer habitats with low or
scattered trees among grassland vegetation—woodland edges, brushy thickets,
prairies, fields, pastures, orchards, and residential areas. Forest
fragmentation has made large areas accessible to cowbirds. In one study in
Ontario, 897 nests were in farmland areas (overgrown fields, fence rows, young
conifer plantations, orchards, open fields), 235 in woodland areas, and 232 in
residential areas.
While
it is true that cowbirds are of conservation concern, we can’t overlook more
immediate challenges to populations, like loss of habitat. The late naturalist
and conservationist David Gaines wrote about this conundrum: "It is all
too easy to vilify cowbirds. True, they have tipped nature's balance to the
detriment of native species. But let us not forget that we, through our use and
abuse of the land, have allowed them to thrive and multiply. Without humans,
there would be no cowbird 'problem'. The blame lies with us, not them."
Black-billed Cuckoo
Speaking of brood parasites, when Mary
and I were in Scotland in early June, we consistently heard European cuckoos
just about wherever we went. These large birds (about the size of a mourning
dove) are the source of the sound heard in cuckoo clocks around the world:
“cuck-oo, cuck-oo, cuck-oo, cuck-oo . . .” Like brown-headed cowbirds, the
European cuckoos lay their eggs in other birds’ nests, and their large,
fast-growing young usually outcompete the host’s chicks.
In
northern Wisconsin, we have black-billed cuckoos that nest usually in thickets
of shrubs like willow and dogwood along wetland edges. Their stacatto
“cu-cu-cu” song is easy to identify. And though they belong to the cuckoo
family, they’re not brood parasites – they raise their own young.
They’re
reclusive, often perching silently in dense shade, so most folks don’t know
they even live in the Northwoods. Linda Johnson sent me a photo of a
black-billed cuckoo that hit her window on July 4 and noted that she didn't
even know there were cuckoos here.
Black-billed
cuckoos are positive forces on the landscape. They consume enormous numbers of
caterpillars, with a demonstrated preference for noxious species, including the
eastern tent caterpillar, fall webworm, and the larvae of the gypsy moth.
Cuckoos have been observed consuming 10 to 15 caterpillars per minute, and thus
provide a great service in forests, farms, and orchards. Stomach contents of
individual cuckoos may contain more than 100 large caterpillars or several
hundred of the smaller species.
Bizarrely, the
bristly spines of hairy caterpillars eventually pierce the cuckoo’s stomach
lining giving it a furry coating, and when the mass finally obstructs
digestion, the entire stomach lining is sloughed off and regurgitated as a
pellet!
Quiet Dawns
I’m not a big fan of mid-July for one major
reason – bird song at dawn drops to virtually nothing. Breeding, nest building,
and territorial defense have come to a close for most species, and singing
males just seem to lose their machismo. I love those first weeks in May when
most birds have returned and dawn singing is at a crescendo, and now it’s
pretty much over until next year.
“A 21st
Century Model for Deer Management”
The deer
trustees report was released last week and makes for interesting reading. To read the full report, go to: http://doa.wi.gov/secy/documents/final_report_recommendations13.pdf
Some
inaccurate responses are already being made to the report. One says, “Some state owned, MFL, and all of the US Forest Service lands are being
managed for old growth. Deer and
other wildlife must have some early successional species, like aspen, available
for forage.”
For the record, it’s true that deer
and some other wildlife do best in early successional habitats like
young aspen; however, deer also need older, dense stands of conifers for best
winter cover. Deer are an excellent example of how the life cycles of wildlife
are often elegantly complex, requiring a thorough knowledge of the many
seasonal changes, microhabitat needs, and interactions with other species that
impact them.
Also,
for the record, most of U.S. Forest Service lands are categorically not
being managed for old-growth. The 2004 Chequamegon-Nicolet National Forest
Master Plan provides for 291,000
acres alone of even-aged aspen management, which means clearcut rotations. Please see the plan at:
www.fs.usda.gov/detail/cnnf/landmanagement/planning/?cid=stelprdb5117262
Celestial
Events
Look on 7/28 for the peak Delta Aquarid meteor
shower, a moderate event that averages 15-25 meteors per hour. Unfortunately,
the show will be partially washed out by the waxing gibbous moon.
The full moon, variously called by American
Indian tribes the Sturgeon/Corn/Woodcutter’s/Ricing moon, occurs on August 1.
Please share
your outdoor sightings and thoughts: call me at 715-476-2828, drop me an e-mail
at manitowish@centurytel.net, or snail-mail me at 4245N Hwy. 47,
Mercer, WI 54547.
