Digging behavior of four species of deer mice (Peromyscus). American Museum novitates ; no. 2429

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New York, N.Y. : American Museum of Natural History
"Certain aspects of digging behavior in four species of deer mice, Peromyscus (P. floridanus, P. gossypinus, P. leucopus, and P. polionotus), were studied to determine the relationships between the level of digging activity and ecological factors and the possible adaptive significance of such correlations. Two populations of each of three of the species (floridanus, gossypinus, and polionotus) were included to provide some indication of the magnitude of intraspecific variation in digging activity, and both field and first generation laboratory-raised subjects of the same species were studied in an attempt to distinguish between the relative influences of genetic and environmental factors on this behavior. Mice were placed individually into an open-field box containing either sand or peat and observed for a five-minute period. In addition to descriptive notes on digging behavior, number of bouts, total time spent digging, and latency (time elapsed between introduction to the apparatus and beginning of first digging bout) were recorded. Peromyscus floridanus dug relatively slowly, using the forefeet for excavating and moving material beneath the body and also to propel the substrate to the rear. In contrast to the other species, the hind feet were rarely used to kick accumulated material backward. Peromyscus gossypinus moved the forefeet more rapidly in excavating material than did floridanus and generally used the hind limbs to throw the substrate behind the body. Details of digging in leucopus were not clearly observed; but it appears to resemble gossypinus in its style of digging. Peromyscus polionotus appeared to be the most efficient digger of the four species. It moved its forefeet more rapidly than the other forms, and the hind limbs were more closely integrated into the total action pattern. Quantitatively, floridanus dug less than the other species, gossypinus and leucopus were slightly more active, whereas polionotus far exceeded all other species in mean number of bouts and total time digging and had distinctly shorter latencies. The well-developed digging behavior of polionotus is correlated with burrowing habits. All species exhibited a tendency to dig more actively on sand rather than on peat, but only in leucopus and polionotus was the discrepancy pronounced. The higher level of digging of polionotus on sand may reflect selection for substrate recognition as a result of the importance of the proper type of soil for burrow construction in this species. There seems to be no obvious adaptive basis for the sand preference of leucopus. Only in polionotus were there appreciable differences between populations in digging behavior, with leucocephalus tending to do more digging than did subgriseus. This difference may reflect more intense selection for digging in the leucocephalus population as a result of more difficult burrow construction and maintenance, constant covering of food items by blowing sand, and greater use of shallow holes to avoid predation. In general, laboratory-raised stocks fell into the same relative position as field groups in the aspects of digging behavior studied, indicating a genetic basis of the differences observed. However, in all stocks except P. p. leucocephalus there was a tendency for reduced digging in laboratory-reared subjects. The differences between field and laboratory-raised groups appear to be of environmental origin, either reflecting the absence of experience on natural substrates or an effect of the homogeneous laboratory environment on other aspects of behavior, such as activity, temperament, etc., which in turn influence digging performance. The fact that laboratory-reared leucocephalus actually dug more than did field subjects may indicate either a stronger genetic basis for digging in this stock or a lesser effect of laboratory conditions, perhaps because of the relative homogeneity of the natural environment of this population compared with that of the other stocks. Differences in the present results and those of previous studies of digging behavior in Peromyscus dealing with some of the same species appear to be attributable to the types of testing apparatus and procedures utilized"--P. 14-15.
16 p. : ill. ; 24 cm.
Includes bibliographical references (p. 15-16).