Nature
Notes for June 30, 2017
What
is the small bird that is singing so much in my garden? It seems to be nesting
in the nest box. Its song is pleasant, but it is really loud.
On
several occasions recently, I have had conversations along this theme.
Since
the birds were using nest boxes in suburban gardens, it was quite easy to
identify as a House Wren. This species always nests in cavities and will
readily nest in a nest box. They are not particularly fussy about the cavity.
An old woodpecker hole, a hole in a rail fence, a tin can, a flower pot, or an
old shoe will all provide a suitable place in which to nest. A few years ago, I
found a House Wren singing vigorously from a bison skull that had been nailed
to a sign at the farm gate of a bison farm near Roseneath. I assumed that the
bird’s nest was in the skull, although I didn’t clamber through the ditch to
check.
House
Wrens are brown or grayish-brown in colour, with next to no pattern. The male
and female have the same plumage. Sometimes they hold their tail erect, but
they are just as likely to hold it straight out.
The song of a male House Wren has been disturbing my neighbour's sleep.
photo © Rob Lonsberry Photography
This
species has quite a broad distribution in the New World. It breeds from
southern Canada through the West Indies and Central America, almost to the tip
of South America. The birds that breed here winter mostly in the southern U.S.
and Mexico. They usually arrive back in southern Ontario in early May.
During
the breeding season, House Wren males sing a loud burbling song, and they sing
and sing and sing. They do this to attract a mate and to mark their territory.
The male will also choose a suitable hole and proceed to fill it with small
twigs. It is quite a chore to find suitable twigs and then poke them into a
nest box until the box is almost full. The male may do this with several nest
boxes, but only one will be used for the nest.
The
chosen nest will have a deep cavity lined with finer grasses. The nest often
also contains other plant material, animal hair, spider egg sacs, string,
snakeskin, and discarded plastic. In the lined cavity, the female will lay her
eggs. Clutch size is usually six to eight eggs. The eggs are pinkish with
blotches of reddish brown. Incubation lasts from 12 to 16 days.
When
the chicks hatch, they are naked and helpless. The young will stay in the nest
from 15 to 19 days. By this time, they are fully feathered and can fly. After
the nestlings fledge, they are still fed by the adults for about two weeks.
Usually,
House Wrens will raise two broods in a breeding season. When the second nest is
initiated, the male will begin to sing again.
House
Wrens eat a wide variety of insects and spiders, including beetles,
caterpillars, earwigs, and daddy longlegs, as well as smaller numbers of more
mobile insects such as flies, leafhoppers, and springtails. It could prove very
beneficial to your garden to have birds that eat the pests of your vegetables
and flowers. They also eat snail shells, probably for the calcium they contain
and to provide grit for digestion.
House
Wrens are very aggressive birds that defend their territories vigorously. They
will chase much larger birds away, scolding loudly. They have been known to
attack nests of other House Wrens, removing or puncturing eggs. They will also
remove or puncture eggs and attack young of other species such as Tree Swallows
or Eastern Bluebirds. Since House Wrens prefer shrubby deciduous habitat and
the other two species named prefer open habitats, careful placement of nest
boxes can reduce depredation by wrens.
As
I write this, I can hear a House Wren singing. My neighbor will have to put up
with a bit more loud song as the wrens in his garden prepare for the second
nesting of the season.
