Showing papers on "Flying squirrel published in 1995"

Northern flying squirrel densities in fir forests of northeastern California

Abstract: The northern flying squirrel (Glaucomys sabrinus) is the primary prey of northern spotted owls (Strix occidentalis caurina) and California spotted owls (S. o. occidentalis) throughout much of the owls' ranges. Flying squirrel abundance patterns, however, are poorly documented. Using capture-recapture techniques to estimate density, we compared flying squirrel densities among 3 types of fir (Abies spp.) forests in Lassen National Forest, northeastern California. We compared densities between 3 each of old and shelterwood-logged fir stands in 1990 and among 4 each of old, shelterwood, and young fir stands in 1991-92. Shelterwood stands had been logged and had undergone site preparation 5 years prior to our study. In 1990 flying squirrel density was greater in old (? = 2.76 squirrels/ha, SE = 0.55) than in shelterwood (? = 0.31 squirrels/ha, SE = 0.11) stands (P = 0.005). In 1991-92 density varied (P = 0.001) among the 3 stand types, averaging 3.29 squirrels/ha (SE = 0.63) in old, 2.28 squirrels/ha (SE = 0.18) in young, and 0.37 squirrels/ ha (SE = 0.17) in shelterwood stands. Body mass of adult males and females and recapture rate did not differ (M, P = 0.438; F, P = 0.983; P = 0.218, respectively) between old and young stands, and percent juveniles captured was greater (P = 0.052) in old than in young stands. Diet analyses were consistent with other studies and indicated that sporocarps of hypogeous fungi were a common food source. Frequency of hypogeous sporocarps was correlated (r s = 0.860, P < 0.001) with flying squirrel density, but cavity density and understory cover were not (P = 0.344 and 0.217, respectively). Flying squirrels were not old-growth specialists; however, low densities in shelterwood stands suggest that heavy logging and intensive site preparation negatively affected flying squirrel populations.

Jaw muscles of new world squirrels

Abstract: The jaw, suprahyoid, and extrinsic tongue muscles are described for eight species of New World squirrels, spanning more than an order of magnitude in body mass Anatomical differences are discussed in the light of body size, natural history, and phylogeny The relative sizes of different muscles, their orientations, and the shapes and positions of their areas of attachment vary but show few trends in relation to body size The anatomical differences are likewise not readily explained by the mechanical requirements of the animals' diets, which are similar The most marked anatomical differences occur in Sciurillus (the pygmy tree squirrel), as well as those genera--Glaucomys (the flying squirrel) and Tamias (the chipmunk)--that are taxonomically most distinct from the tree squirrels Sciurillus is noteworthy for its unusually small temporalis and an anterior deep masseter that is oriented to assist in retraction of the jaw Tamias has a more vertically oriented temporalis and greater inclination in the anterior masseter muscles than the other squirrels, features that may be associated with its large diastema and relatively posteriorly situated cheek teeth, which in turn may relate to its having cheek pouches Our results form a valuable database of information to be used in further studies of functional morphology and phylogeny

Opportunistic Predation by a Broad-winged Hawk on a Southern Flying Squirrel

Abstract: Broad-winged Hawks (Buteo platypterus) take a wide variety of prey, including numerous small mammal species (Rusch and Doerr 1972; Fitch 1974; Mosher and Matray 1974; Rosenfield et al. 1984; and Toland 1986). Flying squirrels (Glaucomys spp.) are probably not regular prey of diurnal raptors due to the squirrel's nocturnal habits (Davis 1974); however, some overlap in raptor and squirrel activity may occur at dawn and dusk. Mosher and Matray (1974) reported a northern flying squirrel (G. sabrinus) brought to a Broad-winged Hawk nest in the Central Adirondacks in New York. Rosenfield et al. (1984) also give an account of a flying squirrel (not identified to species) being brought to a Broadwinged Hawk nest in Lincoln County, Wisconsin. No accounts of Broad-winged Hawks preying on southern flying squirrels (G. volans) have ever been documented. While climbing Red-cockaded Woodpecker (Picoides borealis) cavity trees in the Angelina National Forest in eastern Texas (3l 0 15'N, 94°l5'W), we witnessed human induced opportunistic predation by a Broad-winged Hawk on a southern flying squirrel. The incident occurred at approximately 1000 hours on 12 April 1991 in a longleaf pine (Pinus palustris) stand where we were examining cavities for occupants. RRS was climbing a tree that had two cavities at approximately 9 and 12 m above the ground. The climb required us to use four 3-m interlocking Swedish climbing ladders. As a ladder section was being put into place, two flying squirrels flushed from the lower cavity and climbed to and entered the upper cavity. At this time, an adult Broad-winged Hawk flew in and perched in a tree approximately 40 m from the cavity tree, apparently attracted by the movements of the squirrels. When RRS placed the fourth ladder section on the tree one flying squirrel flushed from the upper cavity. The hawk immediately flew from its perch and caught the squirrel in the tree's crown only 4 m above the climber's head. It then flew off out of sight with its prey.