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Scientific name: Baeolophus bicolor
Common name: Tufted Titmouse
(Information in this Species Page was compiled by David Vogel in Biology 220W, Spring
2005, at Penn State New Kensington) Appearance
The tufted titmouse (Baeolophus bicolor) is a small (4.5 to 5.5 inches
long, 18 to 26 grams), predominately gray, non-migratory bird that is very
common in the eastern and especially the northeastern United States. Male and
female titmice are very similar in size and coloration. Their backs are a dark
gray that fades into light gray and white around to their bellies. They also
have side feathers that are a rusty, reddish brown, and their legs are gray.
They have short, slender beaks, black eyes, and a head crest of tufted feathers.
Habitat
Tufted titmice live in a wide variety of habitats: deciduous forests, orchards,
parks, marshes, suburban yards, and rural farms and fields. In the summer they
are most often found in dense, wooded areas and in the fall and winter are
frequent visitors to the millions of bird feeders maintained by bird lovers
throughout the eastern United States. Wind is an especially important ecological
variable influencing the distribution of the tufted titmouse. They tend avoid
open, windy sites and even stay away from the windward sides of their wooded
habitats. 
Mating, Reproduction and Family Groups
Titmice nest in dead, standing trees. Their nests may be located anywhere from
three to ninety feet above the ground. Nesting pairs are predominately
monogamous through their lives although mating between non-paired individuals
can occur. A mating pair will re-use their nest site year after year. In the
northern regions of their distribution titmice have one brood per year, while in
the southern regions two broods per year are possible. There can be 4 to 8 eggs
in a clutch (with 5 to 7 the most common) and typically 1 to 6 of the young
survive to fledge. The titmice form family groups of 3 to 8 individuals. These
groups may even stay together through the subsequent winter as they gather into
multi-familial and multi-species over-wintering flocks. These flocks are
extremely efficient in finding food and avoiding predators. The titmice in these
flocks establish a numerical dominance that enables them to establish a
behavioral and feeding dominance over other, even larger, species of birds.
Diet
Tufted titmice eat insects, spiders, seeds, and fruit. In their natural
habitats, insects and spiders typically gleaned from over and under the bark of
trees are probably their dominant sources of food. Small fruits and berries that
ripen seasonally (including the berries of poison ivy that ripen in the early
winter) are also important, natural food sources. Tufted titmice, though, are
renowned for their fondness for sunflower seeds and will be very abundant,
especially in the winter, around feeders that feature this high energy food.
Body Fat, Social Position and Predation
The amount of fat an individual titmouse has in its body is a very important
indicator of social position and ecological success. Heavier males with higher
amounts of body fat tend to be lower on the flock’s social dominance hierarchy
than are lighter males with lower amounts of body fat. The more dominant an
individual is, the higher his relative feeding priority will be and, thus, the
more predictable (day to day) his food availability and abundance will be. So,
in these dominant birds, carrying extra stores of energy in their body fat
tissues to enable them to survive a day or two without eating is a burden
without realistic benefit. Lower dominance individuals, though, have less of a
guarantee that they will fully feed in a given day as the food resources
available may be exhausted or seriously depleted by the priority feeding of the
more dominant individuals. These lower dominance individuals, then, may benefit
from the caloric stores of body fat which will ensure their survival during
those periods of lower than baseline caloric consumption. These heavier, higher
body fat birds are slower and less maneuverable than the lighter birds. These
heavier birds also need, on average to forage more extensively and more
frequently to gather their required daily calories. These two considerations
make these heavier birds both more susceptible and more exposed to predators.
Owls, hawks, and kestrels are all opportunistic predators of titmice. Domestic
cats also kill large numbers of titmice each year.
Range
The range of the tufted titmouse continues to expand northward. Possibly this
observation is yet another piece of evidence of the ecological consequences of
global warming. Some researchers, though, have also discussed that the increased
prevalence of bird feeding may also be a possible factor in the expansion of
this species’ range.
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