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NOVEMBER
2005 BIRD OF THE MONTH |
TWO IN THE BUSH
By Linda DeKort
CLICK HERE FOR .PDF VERSION
Last month, for several days, the serviceberry bushes by our
home were buzzing with royal activity. Kinglets of both local species
were flitting and hovering, gleaning the insects from the leaves of the
bush. This gave me a golden and ruby opportunity to compare the field
markings of these two diminutive birds.
The kinglets are some of our smallest birds. The Ruby-crowned (Regulus calendula)
measures only 4.25 inches and weighs about one-quarter of an ounce. The Goldencrowned
(Regulus satrapa) is even smaller; it is 3.25 to 4.00 inches long and weighs about a fifth of an
ounce. Both species are olive green above and have yellow edging on the flight feathers. The underparts
are dusky white. During spring they are grayer and less yellowish than during autumn. They have two bold
white wing bars and the lower wing bar has black below the inner half. Their eyes and short bills are black,
and their legs are dark with yellow feet. Both species feed by gleaning insects from leaves and tips of
branches. Kinglets flick their wings constantly, as often as once per second. They both hover like hummingbirds
but Golden-crowned will often be seen hanging upside down while they are feeding. They can accomplish
this acrobatic maneuver because their feet have grooved soles, which give them clinging power.
Side by side, the two species of North American Kinglets are easy to distinguish. The Goldencrowned
Kinglet has a bold black and white striped facial pattern and gold crown patch compared to the
plain facial pattern and broken bold eye ring of the Ruby-crowned. The red crown patch of the Rubycrowned
is only visible in the male and will only be displayed when he is agitated. The crown patch of the
Golden-crowned is apparent at all times in both sexes; the male exhibits a brighter orange than the female.
The gold crown patch gives it its Latin name Satrapa, meaning a ruler wearing a golden crown.
The Ruby-crowned Kinglets feeding here on the serviceberry bushes in mid-October are on their
way south. They may have bred here or were migrating from other coniferous or mixed coniferousdeciduous
forests in Canada or Alaska. Although they can breed farther north (almost to the north coast of
Alaska) than the Golden-crowned Kinglets, they are apparently less hardy and so migrate earlier and winter
farther south. Winter range is closely related to average temperature; they travel as far south as Guatemala
and avoid areas where the temperature frequently drops below 25 degrees Fahrenheit. There is an altitudinal
as well as longitudinal migration in the Rocky Mountains, as birds retreat from high-altitude breeding
areas. Most wintering birds are found west of the edge of the foothills of the mountains. Ruby-crowned
Kinglet populations can fluctuate widely, declining in response to logging activities or fire, but severe winter
weather appears to have the greatest effect on numbers. Male kinglets apparently winter farther north than
females. Perhaps that makes it easier for them to rush back up here in early spring to claim their territory
and treat us all to their distinct song of early spring: tsee-tsee-tsee churr churr churr tee-da-leet tee-da-leet,
tee-da-leet. The song is usually sung from the upper branches of a spruce tree by males defending their
territory. I recognized this song as a harbinger of spring long before I learned from Pattie Brown the identification
of the tiny bird that produced this loud rollicking melody. Females may also sing, but their song is
shorter and, as would be expected, sung with less machismo.
The Golden-crowned Kinglets that visited us this month might be encountered here again this winter.
We find them commonly on the Christmas Bird Counts; Bigfork Bird Count has recently recorded as
many as 150 individuals. Golden-crowned Kinglets nest in northern conifer forests and prefer to winter in
conifers as well. They are tiny birds, second only to hummingbirds. How they can survive our frosty winters
is remarkable. One of their survival strategies seems to be constant foraging during the day. Goldencrowned
Kinglets are important predators on insect larvae and eggs; insect foods consist of budworms,
aphids, bark beetles, scale insects and others. These insectivorous birds have been shown to consume
84% of budworm larvae and pupae in early stages of a budworm outbreak, illustrating one of the economic
benefits they bestow to the forests they inhabit. Although their food consists primarily of insects, their diet
also includes some tree sap. To survive cold winter nights they roost together, often in tree cavities, to retain
body heat.
Based on the Breeding Bird Survey database, Golden-crowned Kinglets are one of seven species
whose populations declined significantly from 1968 to 1991.
As with Red-breasted Nuthatch, Brown Creeper, and
Mountain Chickadee, this is a species which is impacted
significantly by removal of mature trees from
the environment.
When spring arrives, the song of the Goldencrowned
is much harder to detect than that of the
Ruby-crowned; it is soft and high pitched and consists
of about a dozen ascending notes sometimes
combined with a warbled ending. The call is easier to
detect; it consists of one to five notes on a single
high pitch: zeee, zeee, zeee.
The serviceberry bushes are now bare of
leaves and the kinglets have moved on to more
promising hunting grounds. The Ruby-crowned are
now farther south and some of the Golden-crowned
went with them. The ones that will be staying here
for the winter are probably now in their preferred
conifer forest, foraging high in the trees. I’ll be listening
for their high-pitched call as we walk in the
nearby spruce forest, and I will be grateful to the
serviceberry bush for providing me with close encounters
of both of these royal little birds. When it is
time to plant more shrubs next spring, native serviceberry
bushes are on the top of my list. |
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