Wednesday, January 13, 2010

SCIENTISTS WE CAN BE PROUD OF -- classic scholarship on feral house cat behavior

Degree: PH.D.
Year: 1983
Pages: 00137
Institution: UNIVERSITY OF FLORIDA; 0070
Source: DAI, 45, no. 04B, (1983): 1130
Abstract: Feral house cats (Felis catus) were studied at two sites in the Galapagos Islands. Visual observations, fecal collections, and radio telemetry data were gathered to elucidate their ecology and social organization. Sixty-eight percent of all cats trapped were adults; the adult sex ratio was 2.62 males per female. The density of adult cats at both sites was approximately two cats per square kilometer, although the habitat at each site differed in structure and quality.

Transect analyses revealed that there were temporal fluctuations in prey abundance, while the numbers consumed were often different. There were seasonal differences in diet breadth; the diet was broader in the dry season. A posteriori attempts to determine prey preferences indicated that rats, small birds, lava lizards, and grasshoppers were consumed most frequently. A comparison of estimated daily energy intake and daily energy requirements for males and females indicated that males and pregnant and lactating females probably face energy stresses. The energy stress on pregnant and lactating females may be severe, contributing to their apparent greater mortality.

The plotted movements of radio-collared cats revealed large differences in home range size between sexes and sites. At Cerro Colorado the home ranges were larger and more overlapping than those at Tagus Cove. In the qualitatively richer habitat of Cerro Colorado locations were concentrated near the coast, while those at Tagus Cove were more diffuse. Plots of daily movements revealed that foraging paths at Cerro Colorado crisscrossed frequently, while paths were essentially straight at Tagus Cove. The activity cycle was bimodally crepuscular with the lowest activity in the early afternoon.

Little aggression was seen during dominance interactions at Cerro Colorado, while no interactions were observed at Tagus Cove. From all the collected data it was hypothesized that feral cats are solitary, opportunistic predators with broad diets. Differences in habitat quality between sites resulted in different social organizations, with a dominance hierarchy at Cerro Colorado and olfactory-mediated territoriality at Tagus Cove.

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