Estimating the home ranges of sugar gliders (Petaurus breviceps) (Marsupialia: Petauridae), from grid-trapping and radiotelemetry

Abstract

In this study, we examined the number of captures and radio-locations of sugar gliders (Petaurus breviceps) necessary to give reasonable estimates of home ranges. Using home ranges determined by radiotelemetry (RTHR) as a standard, we compared nine methods of estimating trap home range (THR) from grid-based mark-recapture data. Correlation analysis was employed to determine which method of estimating THR most closely correlated with RTHRs. A minimum of 12 captures appears to be adequate for reasonable long-term THR estimates derived from the harmonic mean measure (HMM, 50% isopleth). When RTHRs were estimated by either the minimum convex polygon method (MCP) or the HMM (95% isopleth) from loci collected every 30min, a minimum of 36 radio-locations was adequate. Mean RTHR estimates for identical data sets were 53 775m*2 and 35 333m*2 calculated from the MCP and the HMM (95% isopleth) respectively. A number of methods for analysing grid-trapping data produced THR estimates that were significantly correlated with RTHR estimates. Correlations were highest when RTHRs were estimated with the HMM as opposed to the MCP. RTHR estimates derived from the MCP were most strongly correlated with THR estimates derived by the minimum area method, HMM (50% isopleth) and observed range circle (r*2>0.48). When RTHR estimates were derived from the HMM (95% isopleth), the same correlations were higher (r*2>0.88) and THRs estimated by the boundary-strip methods and the adjusted range circle were also highly correlated (r*2>0.65). The significance of the correlations suggests that reasonable short-term THR estimates may be obtained from small capture samples by these above-mentioned methods of calculation. The HMM appeared to exhibit the greatest overall utility, with both radio-tracking and grid-trapping data. The success of the HMM in describing home range appears to be in its ability to depict centres of activity. The technique is most appropriate for animals such as sugar gliders which use concentrated but patchily distributed food resources, and consequently display uneven patterns of use of space.

Spatial patterning in nocturnal prosimians: A review of methods and relevance to studies of sociality

“…Because different methods of data collection and data analysis may yield different estimates of home range use Bearder, 1987;Quin et al, 1992], researchers should be aware of the costs and benefits of each method and should aim to use the most reliable methods to meet their study objectives.…”

“…Unfortunately, comparisons among the findings of various published radio tracking studies are problematic, as differences in the procedures used to collect and analyze radio tracking data have provided very different home range estimates Crompton & Andau, 1987;Quin et al, 1992]. In fact, despite the increasing popularity and intensive use of radio tracking in many ecological studies (including studies of nocturnal prosimians) in the past two decades, the reviews of the publications from the second [Lance & Watson, 1980] and the third [Harris et al, 1990] decades of radio tracking both call for a greater standardization of the methods used to collect and analyze tracking data.…”

“…Grid trapping has been used since the 1940s [Burt, 1943;Manville, 1949] to determine patterns of home range use in small mammals. Most studies of home ranges have relied heavily on the use of trap mark methods with grid trapping data, despite the fact that it has long been suspected that trap revealed home ranges differ markedly from true home ranges [Trevor-Deutsch & Hackett, 1980;Harcourt, 1987;Quin et al, 1992]. Reliance on grid trapping may be related to the considerable funds and effort required to tag animals for individual identification and to conduct follows on as many study subjects as possible in studies using radio tracking.…”

“…Home range estimates may be affected by trap locations, size and shape of grids, and frequency of trapping sessions [Bergstrom, 1988;Quin et al, 1992]. Researchers should always report these factors when reporting home range values calculated from trapping data.…”

Use of space by Necromys lasiurus (Rodentia, Sigmodontinae) in a grassland among Atlantic Forest fragments

“…Thus trapping can still be a useful option for studies, such as the present one, where the question asked demands comparisons among home ranges of individuals of different sexes and/or in different seasons. This applies especially if the trapping design aimed to minimize the three problems pointed out above (Jones and Sherman 1983;Quin et al 1992;Lira and Fernandez 2009), as it was tried in this study (see methods). Necromys lasiurus (previously Zygodontomys lasiurus and Bolomys lasiurus) is often among the most abundant rodents in studies carried out in areas of open vegetation in Brazil (e.g.…”