Norman A. Slade

This study was designed to test hypotheses regarding vigilance (a state of alertness that allows an animal to detect the presence of predators or other threats) in white-tailed deer (Odocoileus virginianus). Based on findings on other species, we predicted that: (1) increasing group size would result in decreased individual vigilance; (2) juveniles would be less vigilant than adults; and (3) males would be less vigilant than females. Deer were observed from a tower in northeastern Kansas from May through Jul. 2001 at dawn and dusk. In accordance with other species, individual vigilance was negatively correlated with group size and juveniles spent less time vigilant than adults. However, there was no apparent difference in vigilance levels between the sexes in adults. We conclude that deer exploit loose aggregations to maximize foraging time by decreasing individual vigilance (without increasing risk) and that the trade off between vigilance and foraging intensity changes with maturation.

Based on 13 y of trapping data, captures of the western harvest mouse (Reithrodontomys megalotis) in northeastern Kansas decreased significantly in summer. Reduced rates of capture could have arisen from reduced numbers or behavioral changes. We found a slight decrease in persistence rates in summer, so in June and July 2002, we placed traps on elevated platforms to test whether R. megalotis might be scansorial in summer. Elevated traps were significantly more successful than surface traps. We concluded that apparent disappearance of R. megalotis in summer was attributable to changes in behavior rather than emigration or death. Resumen Basados en datos de trampeo en el noreste de Kansas a lo largo de 13 años, las capturas del ratón cosechero común (Reithrodontomys megalotis) decrecieron significativamente durante los veranos. Menores tasas de captura podrían derivarse de menores números o de cambios en comportamiento. Encontramos una pequeña disminución en la persistencia de individuos de esta especie en trampeo durante el verano. Por lo tanto, durante junio y julio del 2002, colocamos trampas en plataformas elevados para comprobar si R. megalotis son trepadores durante el verano. Las trampas en plataforma fueron significativamente más exitosas que las colocadas en la superficie del suelo. Concluimos que la aparente desaparición de R. megalotis durante el verano se atribuye a cambios de comportamiento más que a emigración o mortandad.

To minimize impact on small mammals while preventing invasion of woody vegetation, we mowed alternating 15-m strips on our area. We then compared num

We provided supplemental food to hispid cotton rats (Sigmodon hispidus) in northeastern Kansas to test for restriction of movements in the presence of additional resources. We estimated movements as the mean squared distance from the centroid of locations for each individual and tested for changes in movements on 2 time scales using mark–recapture data. Movements within a 3-day interval varied with sex, season, and reproductive condition, but we found no significant changes in response to supplemental food. Movements over an individual's entire 1–6-month tenure on our area decreased with added food. Hence, adding food at regularly spaced, point sources did not seem to influence daily movements but reduced the tendency of individuals to shift centers of activity over longer time intervals.

Snap-traps, live-traps, and baits affect the ability to capture small mammals, but few previous studies have involved sampling communities of small mammals in tropical environments. We tested differences in captures of small marsupials and rodents by Victor snap-traps versus Sherman live-traps and by two types of bait in lowland rainforest at Reserva Cuzco Amazónico, southeastern Peru. Snap-traps took ca. 3.5 times as many individuals as live-traps. Snap-traps also captured more species (and more rare species), but we attribute this to more numerous captures overall because the relative proportions of species captured by the two traps generally were the same. Type of bait had little impact on our trapping results.