BIOLOGICAL DATA AND HABITAT REQUIREMENTS
WILDLIFE SPECIES: Dumetella carolinensis | Gray Catbird 



TIMING OF MAJOR LIFE HISTORY EVENTS : 
Breeding Season:  The gray catbird breeds from late April to mid-August,
with the peak season occurring from mid-May to mid-June [11].  The nest
is a ragged mass of sticks, weed stems, grasses, leaves, and twigs.  The
cup may be lined with pine needles, rootlets, fine shreds of bark, and
horsehair [25].  In New York, eggs were laid from May 5 to June 13 [6].
In Ontario, egg dates ranged from May 2 to August 18 [19].  The gray
catbird raises two or more consecutive broods in one season [6].

Clutch Size:  The average clutch size is four, but ranges from three to
five eggs [11].

Development:  Eggs are incubated for 12 to 15 days [2,6].  The female is
usually the sole incubating parent and is fed by the male [2].  The
young usually remain in the nest for 11 days; the nestling stage ranges
from 9 to 15 days.  The gray catbird is sexually mature at 1 year [6].

Migration:  The southward migration of gray catbird begins early in the
fall, soon after the young leave the nest [15].  During one fall study
period as many as 725 gray catbirds were reported at Dauphin Island,
Alabama in a single day [39].  In the spring, males arrive on nesting
grounds prior to the females [25].  Gray catbirds were the second most
frequently captured species in the spring in a study area on the Fort
Morgan Peninsula, Alabama [39].  Banded birds usually return to the
place of banding.  There is variation in the constancy of mating; some
catbird pairs raise consecutive broods in the same season and remain
paired in subsequent seasons.  Other pairs raise one brood and then find
new mates, although the male appears to remain constant to a territory
[2].

Maximum longevity is 10 years [25].  Average longevity is around 2.5
years [2].


PREFERRED HABITAT : 
The gray catbird uses dense thickets of shrubby edge habitat for both
nesting and foraging.  Any area of dense shrubs, briars, or vines along
woodland borders appears to be suitable [7].  The habitat niche breadth
is fairly large, meaning that gray catbirds use a wide variety of
foliage densities and shrub layers.  The gray catbird is also found in
dry marsh edges, roadside shrubs, abandoned fields, and fencerows [7].

Sample gray catbird densities are as follows:  In New York, one nest per
8 acres (3.2 ha) (80 pairs per square mile [31/sq km]) was reported for
mixed shrub-small tree stages in beech (Fagus spp.)-maple (Acer
spp.)-hemlock (Tsuga spp.) forest [6].  In North Dakota, 40 pairs per
square mile (15 per sq km) were observed in favorable habitat [22], and
in Maryland, 80 males were counted for 100 acres (40 ha) in shrub swamp
habitat [23].  In Iowa, there was a positive relationship between gray
catbird density and sapling richness, tree size, and tree patchiness,
and a negative relationship with tree density [21].


COVER REQUIREMENTS : 
The gray catbird uses dense, shrubby vegetation for all activities.
Nests are usually constructed about 5 feet (1.5 m) [6] above the ground,
with a range of 3 to 10 feet (1-3 m) above the ground in dense, leafy
shrubs or vines [7].  In Iowa riparian habitat, 72 out of 97 nests were
constructed in shrubs, 11 were found in deciduous saplings, and 14 in
deciduous trees [21].


FOOD HABITS : 
The gray catbird is primarily a leaf-gleaner [36].  About half of
the diet is insects; the fleshy fruits of woody shrubs constitute most
of the remainder of the diet [7,15].

Animal foods include ants, beetles, crickets and grasshoppers, bugs,
cankerworms and other smooth caterpillars, caterpillars of gypsy moth
and brown-tailed moth, aphids, miscellaneous other insects, and spiders
[15,25].

Plant foods (fruit) include blackberries (Rubus spp.), cherries (Prunus
spp.) including chokecherry (P. virginiana), hollies (Ilex spp.),
bayberries (Myrica spp.), greenbriers (Smilax spp.), poison-ivy
(Toxicodendron spp.), buckthorns (Rhamnus spp.), tatarian honeysuckle
(Lonicera tatarica), Missouri gooseberry (Ribes missouriense), American
elder (Sambucus canadensis), blueberries (Vaccinium spp.), baneberry
(Actaea rubra), dogwoods (Cornus spp.), and buffaloberries (Shepherdia
spp.) [14,15,17,29,36,37].


PREDATORS : 
Snakes are major predators on gray catbird nestlings, as are rats,
foxes, and domestic cats.  Other nest molesters include common grackle
(Quiscalus quiscula), brown thrasher (Toxostoma rufum), and northern
cardinal (Cardinalis cardinalis).  Adult catbirds are taken by northern
harrier (Circus cyaneus), peregrine falcon (Falco peregrinus), and
long-eared owl (Asio otus) [2].  Toland [26] listed a gray catbird as a
nesting season prey item for a red-tailed hawk (Buteo jamaicensis).


MANAGEMENT CONSIDERATIONS : 
Gray catbirds were rated as tolerant of habitat alteration; they do not
require a specific habitat and are able to make use of
less-highly-preferred habitat, albeit at lower densities [21].

In Pennsylvania, gray catbirds were present in clearcut stands of aspens
and oak-pine.  They were observed to use the edges of stands more often
than interiors (defined as more than 83 feet [25 m] from the interface),
and preferred older stands [30].  Nongame bird densities were censused
in bigtooth aspen (Populus grandidentata)-quaking aspen-pitch pine
(Pinus rigida), and in bear oak (Quercus ilicifolia)-dwarf chinkapin oak
(Q. prinoides)/blueberry stands that were uncut, 50 percent clearcut,
or 75 percent clearcut.  Length of time since treatment was 2, 6, or 12
years.  Gray catbirds were encountered more often than expected in 75
percent clearcut aspen stands and were not encountered in uncut stands
of either aspens or oaks.  Within the 50 percent clearcut stands, gray
catbirds were more common in 12-year-old stands of both aspens and
oak-pine than in 2-year-old stands [32].

Stauffer and Best [21] made the following predictions about the effect of
habitat alteration on gray catbird density:

1) conversion of woody vegetation to hayfield or pasture will eliminate
     gray catbird
2) reduction of woody vegetation to narrow strips along streams will
     reduce gray catbird density
3) partial removal of the canopy will increase gray catbird density
4) thinning of shrub and sapling layers will reduce gray catbird density.

The authors were unable to make a prediction for the effect of partial canopy
removal with shrub thinning, since the separate treatments have opposite
effects [21].

Tall structures create a hazard to migrating gray catbirds because most
migration occurs at night [25].  Structures listed as hazards include
lighthouses and the Washington Monument [2].

Nest Parasitism:  Gray catbirds are infrequent hosts to brown-headed
cowbirds.  Gray catbirds will eject eggs of other species that are found
in the nest [25].  However, if a naive gray catbird is exposed to a
brown-headed cowbird egg before her own eggs are laid, she will "learn"
the cowbird egg, eject her own eggs, and rear the cowbird chick [38].


REFERENCES : 
NO-ENTRY

Related categories for Wildlife Species: Dumetella carolinensis | Gray Catbird