American Society of Mammalogists

Food Habits of Sympatric Peromyscus leucopus and Peromyscus maniculatusAuthor(s): Jerry O. Wolff, Raymond D. Dueser and Kendell S. BerrySource: Journal of Mammalogy, Vol. 66, No. 4 (Nov., 1985), pp. 795-798Published by: American Society of MammalogistsStable URL: http://www.jstor.org/stable/1380812 .

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GENERAL NOTES GENERAL NOTES

FINGER, S. E., I. L. BRISBIN, JR., AND M. H. SMITH. 1981. Kidney fat as a predictor of body condition in white-tailed deer. J. Wildl. Mgmt., 45:964-968.

HARRIS, D. 1945. Symptoms of malnutrition in deer. J. Wildl. Mgmt., 9:319-322.

Low, W. A. 1970. The influence of aridity on re- production of the collared peccary (Dicotyles ta- jacu (Linn.)) in Texas. Unpubl. Ph.D. dissert., Univ. British Columbia, Vancouver, 170 pp.

NEILAND, K. A. 1970. Weight of dried marrow as indicator of fat in caribou femurs. J. Wildl. Mgmt., 34:904-907.

NICHOLS, R. G., AND M. R. PELTON. 1972. Varia- tions in fat levels of mandibular cavity tissue in white-tailed deer (Odocoileus virginanus) in Ten- nessee. Proc. Ann. Conf. Southeast. Assoc. Game Fish Comm., 26:57-68.

? 1974. Fat in the mandibular cavity as an indicator of condition in deer. Proc. Ann. Conf. Southeast. Assoc. Game Fish Comm., 28:540-548.

FINGER, S. E., I. L. BRISBIN, JR., AND M. H. SMITH. 1981. Kidney fat as a predictor of body condition in white-tailed deer. J. Wildl. Mgmt., 45:964-968.

HARRIS, D. 1945. Symptoms of malnutrition in deer. J. Wildl. Mgmt., 9:319-322.

Low, W. A. 1970. The influence of aridity on re- production of the collared peccary (Dicotyles ta- jacu (Linn.)) in Texas. Unpubl. Ph.D. dissert., Univ. British Columbia, Vancouver, 170 pp.

NEILAND, K. A. 1970. Weight of dried marrow as indicator of fat in caribou femurs. J. Wildl. Mgmt., 34:904-907.

NICHOLS, R. G., AND M. R. PELTON. 1972. Varia- tions in fat levels of mandibular cavity tissue in white-tailed deer (Odocoileus virginanus) in Ten- nessee. Proc. Ann. Conf. Southeast. Assoc. Game Fish Comm., 26:57-68.

? 1974. Fat in the mandibular cavity as an indicator of condition in deer. Proc. Ann. Conf. Southeast. Assoc. Game Fish Comm., 28:540-548.

RANSOM, A. B. 1965. Kidney and marrow fat as indicators of white-tailed deer conditions. J .Wildl. Mgmt., 29:397-398.

RINEY, T. 1955. Evaluating condition of free-rang- ing red deer, with special reference to New Zea- land. New Zealand Sci. Tech., 36(B):428-463.

STRIBLING, H. L., I. L. BRISBIN, JR., J. R. SWEENEY, AND L. A. STRIBLING. 1984. Body fat reserves and their prediction in two populations of feral swine. J. Wildl. Mgmt., 48:635-639.

SUTTIE, J. M. 1983. The relationship between kid- ney fat index and marrow fat percentage as in- dicators of condition in red deer stags (Cervus elaphus). J. Zool., London, 201:563-565.

WARREN, R. J. 1979. Physiological indices for the assessment of nutritional status in white-tailed deer. Unpubl. Ph.D. dissert., Virginia Polytechnic Inst. and State Univ., Blacksburg, 250 pp.

RANSOM, A. B. 1965. Kidney and marrow fat as indicators of white-tailed deer conditions. J .Wildl. Mgmt., 29:397-398.

RINEY, T. 1955. Evaluating condition of free-rang- ing red deer, with special reference to New Zea- land. New Zealand Sci. Tech., 36(B):428-463.

STRIBLING, H. L., I. L. BRISBIN, JR., J. R. SWEENEY, AND L. A. STRIBLING. 1984. Body fat reserves and their prediction in two populations of feral swine. J. Wildl. Mgmt., 48:635-639.

SUTTIE, J. M. 1983. The relationship between kid- ney fat index and marrow fat percentage as in- dicators of condition in red deer stags (Cervus elaphus). J. Zool., London, 201:563-565.

WARREN, R. J. 1979. Physiological indices for the assessment of nutritional status in white-tailed deer. Unpubl. Ph.D. dissert., Virginia Polytechnic Inst. and State Univ., Blacksburg, 250 pp.

Submitted 15 October 1984. Accepted 15 February 1985.

J. Mamm., 66(4):795-798, 1985

FOOD HABITS OF SYMPATRIC PEROMYSCUS LEUCOPUS AND PEROMYSCUS MANICULATUS

JERRY 0. WOLFF, RAYMOND D. DUESER, AND KENDELL S. BERRY

Department of Biology, University of Virginia, Charlottesville, VA 22901 (JOW) Department of Environmental Sciences, University of Virginia, Charlottesville, VA 22901 (RDD)

Blue Ridge School, Dyke, VA 22935 (KSB)

The white-footed mouse (Peromyscus leucopus noveboracensis) and the cloudland deermouse (P. maniculatus nubiterrae) occur sympatrically in the southern Appalachian Mountains of the eastern United States. In a series of experiments to test for competition between these species, we have found that they exploit similar microhabitats (R. Dueser and J. Wolff, unpubl.; Harney, 1983), use similar nest sites (Wolff and Hurlbutt, 1982), are intra- and inter-specifically territorial (Wolff et al., 1983), and under some con- ditions are food-limited (Gerzoff, 1984). In this paper we provide further evidence for their ecological similarity by comparing their seasonal diets.

The study was conducted at Mountain Lake Biological Station, Giles Co., in southwestern Virginia. The vegetation is oak-maple-hickory forest with scattered rhododendron thickets and an understory of ferns (primarily Osmundia spp.) and blueberry (Vaccinium spp.). For a further description of the study area see Wolff and Hurlbutt (1982) and Wolff et al. (1983).

Stomach contents were analyzed from 109 P. leucopus and 70 P. maniculatus collected from June to August 1981 (summer), November 1981 (autumn), and February 1982 (winter), using the procedures of Baumgardner and Martin (1939), Dusi (1949), and Wolff (1978). Stomach contents from snap-trapped animals were washed over a 0.125 mm2 sieve, boiled in Hertwig's solution for one minute, and stained with hematoxylin solution. Approximately equal samples for each stomach were placed on microscope slides, mounted with Karo syrup, and covered with 20 mm x 40 mm cover slips.

Twenty fields were observed per slide under 100x magnification and the presence of each food item type within each field was recorded. If a field had no food items present, then another field was chosen. Because food items were of varying sizes, but equal importance, only their presence or absence in each field

Submitted 15 October 1984. Accepted 15 February 1985.

J. Mamm., 66(4):795-798, 1985

FOOD HABITS OF SYMPATRIC PEROMYSCUS LEUCOPUS AND PEROMYSCUS MANICULATUS

JERRY 0. WOLFF, RAYMOND D. DUESER, AND KENDELL S. BERRY

Department of Biology, University of Virginia, Charlottesville, VA 22901 (JOW) Department of Environmental Sciences, University of Virginia, Charlottesville, VA 22901 (RDD)

Blue Ridge School, Dyke, VA 22935 (KSB)

The white-footed mouse (Peromyscus leucopus noveboracensis) and the cloudland deermouse (P. maniculatus nubiterrae) occur sympatrically in the southern Appalachian Mountains of the eastern United States. In a series of experiments to test for competition between these species, we have found that they exploit similar microhabitats (R. Dueser and J. Wolff, unpubl.; Harney, 1983), use similar nest sites (Wolff and Hurlbutt, 1982), are intra- and inter-specifically territorial (Wolff et al., 1983), and under some con- ditions are food-limited (Gerzoff, 1984). In this paper we provide further evidence for their ecological similarity by comparing their seasonal diets.

The study was conducted at Mountain Lake Biological Station, Giles Co., in southwestern Virginia. The vegetation is oak-maple-hickory forest with scattered rhododendron thickets and an understory of ferns (primarily Osmundia spp.) and blueberry (Vaccinium spp.). For a further description of the study area see Wolff and Hurlbutt (1982) and Wolff et al. (1983).

Stomach contents were analyzed from 109 P. leucopus and 70 P. maniculatus collected from June to August 1981 (summer), November 1981 (autumn), and February 1982 (winter), using the procedures of Baumgardner and Martin (1939), Dusi (1949), and Wolff (1978). Stomach contents from snap-trapped animals were washed over a 0.125 mm2 sieve, boiled in Hertwig's solution for one minute, and stained with hematoxylin solution. Approximately equal samples for each stomach were placed on microscope slides, mounted with Karo syrup, and covered with 20 mm x 40 mm cover slips.

Twenty fields were observed per slide under 100x magnification and the presence of each food item type within each field was recorded. If a field had no food items present, then another field was chosen. Because food items were of varying sizes, but equal importance, only their presence or absence in each field

November 1985 November 1985 795 795

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TABLE 1.-Mean percentage frequency of occurrence for each item eaten by Peromyscus leucopus and P. maniculatus. (Standard error).

Summer Autumn Winter Total

Pl Pm Pi Pm Pi Pm Pi Pm n = 78 n = 40 n = 18 n = 20 n = 13 n = 10 n = 109 n = 70

Arthropods 44.0 (2.62) 56.0 (4.00) 43.6 (4.67) 30.0 (3.62) 45.8 (7.35) 45.9 (7.15) 44.1 (2.18) 47.1 (3.00) Lepidopteran

larvae 4.7 (0.95) 3.8 (1.30) 0 (0) 0.2 (0.16) 1.2 (0.89) 1.5 (0.63) 3.5 (0.71) 2.4 (0.76) Lepidopteran

adults 4.5 (1.31) 3.4 (1.31) 34.2 (6.67) 25.6 (4.32) 5.2 (2.61) 6.7 (2.94) 9.5 (1.80) 10.2 (1.89) Fruit 25.0 (3.07) 24.5 (4.24) 0.4 (0.40) 3.5 (2.06) 0 (0) 1.1 (0.73) 18.0 (2.44) 15.1 (2.80) Green vegetation 10.8 (1.63) 4.7 (1.14) 2.3 (1.46) 12.3 (3.35) 14.3 (3.27) 17.5 (3.76) 9.8 (1.26) 8.6 (1.40) Fungi 6.8 (6.80) 7.2 (2.60) 0 (0) 0.3 (0.29) 0 (0) 1.0 (1.01) 4.9 (1.08) 4.3 (1.54) Nuts/Seeds 0 (0) 0 (0) 15.2 (5.82) 24.0 (6.98) 28.5 (7.96) 23.1 (9.68) 5.9 (1.63) 10.2 (2.75) Unknown 4.2 (1.29) 0.8 (0.41) 4.4 (2.17) 4.1 (2.12) 5.1 (3.49) 3.0 (1.96) 4.3 (1.06) 2.0 (0.72)

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GENERAL NOTES

of view was recorded and not the actual number of food "bits." Percent frequency of occurrence was computed for each food item. Reference slides for food items were made by feeding test mice a known monotypic diet and making a slide from the stomach contents using the procedure described above. All percentages were arc-sin transformed for statistical analysis.

The most common food items for both species included arthropods, fruit, and nuts with lesser amounts of green vegetation and fungi (Table 1). Multi-variate analysis of variance with observations grouped by species and season of capture revealed no significant overall difference between the diets of the two species (MANOVA F = 1.128, d.f. = 8, 166, P = 0.347; SPSS, Hull and Nie, 1981). In fact, there were no overall univariate differences between species for any of the eight categories of food items (all P > 0.200). Both the seasonal effect (MANOVA F = 17.641; d.f. = 16, 334; P - 0.001) and the species-by-season interaction (MANOVA F = 2.569; d.f. = 16, 334; P < 0.001) were highly significant. The seasonal effect indicates that Peromyscus food habits vary from season to season. In fact, there were univariate differences between seasons for seven of the eight categories of food items, all except "unknown" (all P < 0.006). Both species ate more fleshy fruit in summer, more moths and butterflies in autumn, and more nuts in autumn and winter than in other seasons. This most likely is due to the seasonal availability of these food items. Fresh fruit is available in the summer and acorns (Quercus spp.) and hickory nuts (Carya spp.), as well as other dry fruits, are available during autumn and winter. Arthropods, especially insects, are available to Pero- myscus throughout the year in the study area because of the abundance of thick humus and the high density of fallen and decaying trees, which support a large number and variety of insects (Hamilton, 1941; Schloyer, 1976).

The species-by-season interaction indicates that the stomach contents of the two species did not vary between seasons in precisely the same way. In particular, P. maniculatus ate more arthropods in summer than did P. leucopus (56% of mean diet vs. 44%, respectively), whereas in autumn P. leucopus ate more arthropods than P. maniculatus (43.6% vs. 30.0%). Peromyscus leucopus ate more green vegetation in summer (10.8% vs. 4.7%), whereas P. maniculatus ate more in autumn (12.3% vs. 2.3%). Neither species ate nuts in summer, but in autumn P. maniculatus ate more than P. leucopus (24.0% vs. 15.2%, respectively).

The food habits of P. leucopus and P. maniculatus in this study are very similar to those of the Pero- myscus species reported elsewhere. Hamilton (1941) examined 180 P. leucopus noveboracensis between November and April in central New York and found the percent frequency of occurrence for their diet was 72.8% arthropods, 43.9% nuts/seeds, 20.5% green plant matter, and 11.7% other items. Between May and October the percent frequency of occurrence for their diet was 71.0% arthropods, 52.3% fruit, 20.8% nuts/seeds, 3.7% fungi, and 9.8% other items. The summer diet of 142 P. leucopus from New York consisted of 51.0% nuts/seeds, 26.6% arthropods, 15.3% green plant matter, and 7.2% other items (Whitaker, 1963). Whitaker (1966) also examined 113 P. maniculatus bairdii stomachs from Indiana and found that their diets consisted of 39.0% nuts/seeds, 25.8% arthropods, 19.8% green plant matter and 8.4% other items. Martell and Macauley (1981) examined the stomach contents of 712 P. maniculatus between May and September in northern Ontario. They found the diets to consist of 47.2% arthropods, 22.9% nuts/seeds, 16.6% fruit, 9.3% fungi, 1.7% green plant material, and 2.6% achlorophyllous plant matter. It appears as though P. leucopus and P. maniculatus eat similar foods throughout their range in eastern North America.

In the present study P. leucopus and P. maniculatus fed mainly on arthropods, fruit, and nuts. In cafeteria-type feeding tests with these species, Berry (1984) found that both species prefer arthropods, fruit, and nuts, while rejecting green vegetation and fungi. There was no statistical demonstration of partitioning of food by these species in any of the seven food categories identified. The species-by-season analysis of their food habits showed that in autumn P. maniculatus ate more green vegetation and nuts than P. leucopus and P. leucopus ate more arthropods than P. maniculatus. It is doubtful, however, that this difference is significant enough to conclude that these species are coexisting by partitioning food. During summer and winter their dietary similarity (Gauch, 1973) was greater than 90%.

Peromyscus leucopus noveboracensis and P. m. nubiterrae exhibited similar food habits during this period of study. Our study was conducted during a peak density of 40 to 60 mice/ha when the potential for competition would presumably be the greatest. The food habits of sympatric P. leucopus and P. manicu- latus have not been studied during low population densities, but it is doubtful that they would differ enough to affect their ecological relationships. The results of our study and those cited previously give no indication that these species partition either food or microhabitat. Apparent food limitation (Gerzoff, 1984) and extreme overlap in food habits and in habitat (op. cit.) should set the stage for competition. The competitive inter- actions between these species will be discussed elsewhere.

This work was conducted at the Mountain Lake Biological Station and was supported by NSF grant 81- .05177 to J. 0. Wolff and R. D. Dueser.

November 1985 797

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JOURNAL OF MAMMALOGY JOURNAL OF MAMMALOGY

LITERATURE CITED LITERATURE CITED

BAUMGARDNER, L. L., AND H. C. MARTIN. 1939. Plant histology as an aid in squirrel food-habits studies. J. Wild. Mgmt., 3:1266-1268.

BERRY, K. S. 1984. Food habits of two sympatric species of Peromyscus (Rodentia: Cricetidae). Un- publ. M.S. thesis, Univ. Virginia, 30 pp.

DusI, J. L. 1949. Methods for determination of food habits by plant microtechniques and histology and their application to cottontail rabbit food habits. J. Wild. Mgmt., 13:295-288.

GAUCH, H. G. 1973. The relationship beween sam- ple similarity and ecological distance. Ecology, 54: 618-622.

GERZOFF, R. B. 1984. The effect of supplemental food on two sympatric Peromyscus species. Un- publ. M.S. thesis, Univ. Virginia, 101 pp.

HAMILTON, W. J. 1941. The food of small forest mammals in eastern United States. J. Mamm., 22: 250-263.

HARNEY, B. A. 1983. Interspecific competition, ar- boreal habitat use, and the coexistence of two Peromyscus species. Unpubl. M.S. thesis, Univ. Virginia, 54 pp.

HULL, C. H., AND N. H. NIE. 1981. SPSS update 7-9. McGraw-Hill, New York, 102 pp.

BAUMGARDNER, L. L., AND H. C. MARTIN. 1939. Plant histology as an aid in squirrel food-habits studies. J. Wild. Mgmt., 3:1266-1268.

BERRY, K. S. 1984. Food habits of two sympatric species of Peromyscus (Rodentia: Cricetidae). Un- publ. M.S. thesis, Univ. Virginia, 30 pp.

DusI, J. L. 1949. Methods for determination of food habits by plant microtechniques and histology and their application to cottontail rabbit food habits. J. Wild. Mgmt., 13:295-288.

GAUCH, H. G. 1973. The relationship beween sam- ple similarity and ecological distance. Ecology, 54: 618-622.

GERZOFF, R. B. 1984. The effect of supplemental food on two sympatric Peromyscus species. Un- publ. M.S. thesis, Univ. Virginia, 101 pp.

HAMILTON, W. J. 1941. The food of small forest mammals in eastern United States. J. Mamm., 22: 250-263.

HARNEY, B. A. 1983. Interspecific competition, ar- boreal habitat use, and the coexistence of two Peromyscus species. Unpubl. M.S. thesis, Univ. Virginia, 54 pp.

HULL, C. H., AND N. H. NIE. 1981. SPSS update 7-9. McGraw-Hill, New York, 102 pp.

MARTELL, A. M., AND A. L. MACAULEY. 1981. Food habits of deer mice (Peromyscus maniculatus) in northern Ontario. Canadian Field-Naturalist, 95: 319-324.

SCHLOYER, C. R. 1976. Changes in food habits of Peromyscus maniculatus nubiterrae (Rhoads) on clear cut in West Virginia. Proc. Pennsyl. Acad. Sci., 50:78-80.

WHITAKER, J. 0. 1963. Food of 120 Peromyscus leucopus from Ithaca, N.Y. J. Mamm., 44:418- 419.

1966. Food for Mus musculus, Peromys- cus maniculatus bairdii and Peromyscus leucopus in Vigo County, Indiana. J. Mamm., 47:473-486.

WOLFF, J. 0O. 1978. Food habits of Snowshoe Hares in interior Alaska. J. Wild. Mgmt., 42:148-153.

WOLFF, J. O., AND B. HURLBUTT. 1982. Day ref- uges of Peromyscus leucopus and Peromyscus maniculatus. J. Mamm., 63:660-668.

WOLFF, J. O., M. H. FREEBERG, AND R. D. DUESER. 1983. Interspecific territoriality in two sympatric species of Peromyscus (Rodentia: Cricetidae). Be- hav. Ecol. Sociobiol., 12:237-242.

MARTELL, A. M., AND A. L. MACAULEY. 1981. Food habits of deer mice (Peromyscus maniculatus) in northern Ontario. Canadian Field-Naturalist, 95: 319-324.

SCHLOYER, C. R. 1976. Changes in food habits of Peromyscus maniculatus nubiterrae (Rhoads) on clear cut in West Virginia. Proc. Pennsyl. Acad. Sci., 50:78-80.

WHITAKER, J. 0. 1963. Food of 120 Peromyscus leucopus from Ithaca, N.Y. J. Mamm., 44:418- 419.

1966. Food for Mus musculus, Peromys- cus maniculatus bairdii and Peromyscus leucopus in Vigo County, Indiana. J. Mamm., 47:473-486.

WOLFF, J. 0O. 1978. Food habits of Snowshoe Hares in interior Alaska. J. Wild. Mgmt., 42:148-153.

WOLFF, J. O., AND B. HURLBUTT. 1982. Day ref- uges of Peromyscus leucopus and Peromyscus maniculatus. J. Mamm., 63:660-668.

WOLFF, J. O., M. H. FREEBERG, AND R. D. DUESER. 1983. Interspecific territoriality in two sympatric species of Peromyscus (Rodentia: Cricetidae). Be- hav. Ecol. Sociobiol., 12:237-242.

Submitted 25 May 1984. Accepted 19 February 1985.

J. Mamm., 66(4):798-800, 1985

DIFFERENTIAL CAPTURE BETWEEN OLD AND NEW MODELS OF THE MUSEUM SPECIAL SNAP TRAP

STEPHEN D. WEST

College of Forest Resources AR-10, University of Washington, Seattle, WA 98195

The Museum Special snap trap has been a primary means of capturing small mammals for decades. During this time the design of the trap has been changed, most recently by replacing the wood and metal treadle of the older model with a larger plastic treadle. Using a mix of old and new models of trap, data from a study of small mammals on the H. J. Andrews Experimental Forest in the Cascade Mountains of Oregon suggested that rates of capture of different species were not the same with the two models. The largest rodent captured (Tamias townsendii) often was found alive in the new model, but much less commonly in the old model, suggesting that strength of the trap spring was different. Because this disparity seemed large enough to result in significant differences in capture frequencies, I analyzed the performance of the two models by comparing field captures of small mammals and by measuring spring strength and treadle release pressure in the laboratory.

During May and June 1983, the trap model was noted for all small mammals captured. A mixture of old traps (obtained in 1974 from the Woodstream Corporation) and new traps (obtained in 1983) was used, totaling 7,866 trap nights for the old model and 20,806 trap nights for the new model. At the conclusion of trapping, a random sample of 100 traps of each model was drawn for laboratory measurements. All traps used were in good working order. To compare spring strengths, Pesola scales (300 g and 2.5 kg capacity) were used to measure the force required to lift the bail wire of a sprung trap from the trap surface. The force necessary to release a set trap was measured by using a series of small sandbags which varied from 1 to 15 g in 1-g increments.

Submitted 25 May 1984. Accepted 19 February 1985.

J. Mamm., 66(4):798-800, 1985

DIFFERENTIAL CAPTURE BETWEEN OLD AND NEW MODELS OF THE MUSEUM SPECIAL SNAP TRAP

STEPHEN D. WEST

College of Forest Resources AR-10, University of Washington, Seattle, WA 98195

The Museum Special snap trap has been a primary means of capturing small mammals for decades. During this time the design of the trap has been changed, most recently by replacing the wood and metal treadle of the older model with a larger plastic treadle. Using a mix of old and new models of trap, data from a study of small mammals on the H. J. Andrews Experimental Forest in the Cascade Mountains of Oregon suggested that rates of capture of different species were not the same with the two models. The largest rodent captured (Tamias townsendii) often was found alive in the new model, but much less commonly in the old model, suggesting that strength of the trap spring was different. Because this disparity seemed large enough to result in significant differences in capture frequencies, I analyzed the performance of the two models by comparing field captures of small mammals and by measuring spring strength and treadle release pressure in the laboratory.

During May and June 1983, the trap model was noted for all small mammals captured. A mixture of old traps (obtained in 1974 from the Woodstream Corporation) and new traps (obtained in 1983) was used, totaling 7,866 trap nights for the old model and 20,806 trap nights for the new model. At the conclusion of trapping, a random sample of 100 traps of each model was drawn for laboratory measurements. All traps used were in good working order. To compare spring strengths, Pesola scales (300 g and 2.5 kg capacity) were used to measure the force required to lift the bail wire of a sprung trap from the trap surface. The force necessary to release a set trap was measured by using a series of small sandbags which varied from 1 to 15 g in 1-g increments.

798 798 Vol. 66, No. 4 Vol. 66, No. 4

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