PARENT SESSION

Natural History 1 -- Session Chair: Patrick Zollner-- Nelson Hall East, Goodwin Forum

VARIATION IN SMALL MAMMAL RICHNESS BY TRAP HEIGHT AND TRAP TYPE AT A SOUTH EASTERN AMAZONIAN SITE, WITH NOTES ON A NEW METHOD OF CANOPY TRAPPING. Thomas D. Lambert¹, Jay R. Malcolm¹ and Barbara L. Zimmerman². ¹ Faculty of Forestry, University of Toronto, 33 Willcocks Street, Toronto, ON, Canada; ² Brazil Program, Conservation International, 1919 M St. NW, Washington, DC, USA.

ABSTRACT- Despite its biological richness, the rodent and marsupial fauna of the Amazon Basin remains poorly known and the efficacy of different methods in assessing its diversity are poorly understood. We present results of small mammal trapping at a previously unsurveyed site in the Xingu Basin of the south eastern Amazon, Para, Brazil. Mammals were live-trapped at three trap heights: ground, understory (1-3 m above ground) and canopy (height ² =11.5±3.2, range=4.8-16.8m, n=76). Details are provided on a new canopy trapping method, which did not require tree climbing and appears to be the most efficient yet developed. We recorded 1,769 captures of 1,178 individuals of 8 species of marsupials and 17 species of rodents in 38,090 trap nights or 19,320 station nights (a station night consisted of one Sherman and one Tomahawk live-trap at one height for a night, except in a few cases). Our captures included several major range extensions, and at least one new species. Overall trap success was 6.1% individuals per 100 station nights; success by trap position was 9.0% for ground (7,850 station nights), 4.7% for understory (7,850 station nights), and 2.9% for canopy (3,490 station nights). Success by trap type was 4.7% for Shermans and 5.9% for Tomahawks, with Tomahawk traps showing a more rapid accumulation of species. Rarefied species accumulation curves showed little improvement with the inclusion of canopy trapping, which we attribute to the high variability in canopy development at the site. We suggest that in areas with low and broken canopies only ground and understory traps need be employed for long-term studies; however, some form of canopy trapping should be used during initial surveys so the utility of arboreal trapping can be evaluated.

KEY WORDS: Small Mammals, Arboreal Trapping, Amazon, Trap success