A comparison of population estimates and abundance indices for house mice inhabiting beech forests in New Zealand

Abstract

Populations of house mice were sampled on nine grids in Fiordland National Park between May and November 1999, using live-capture and footprint-tracking tunnel methods. Trapped mice were removed from three grids (approximately 3.24 ha each), and marked and released on the other six. Density estimates were obtained using recapture data from the grids where mice were released (Mh (jackknife) model from program CAPTURE), and rate-of-capture data from grids where mice were removed (Mbh (removal) CAPTURE model). Density estimates were used to evaluate the performance of 4 indices of mouse abundance by contrasting R2-values of their regression on estimated mouse density. Indices evaluated were: minimum number of individuals known to be alive (MNA) (total number of individual mice caught over the course of a trapping session), one-night trap catch (number of mice caught on first night of each trapping session expressed as captures per 100 trap-nights), three-night trap catch (same index estimated from number of mice caught over the first three nights), and tracking-tunnel index (proportion of nine tunnels that had mouse tracks). While MNA, one-night trap catch, and three-night trap catch were all significantly correlated with estimated density, MNA was most strongly correlated, with R2 varying between 0.67 to 0.87 depending on whether 3, 4 or 5 nights’ capture data were used. Variation in tracking-tunnel index was unrelated to mouse density on our grids.

Unexpected Consequences Of Vertebrate Pest Control: Predictions From A Four-Species Community Model

“…Estimates were such that certain criteria of the model output fitted the community dynamics of eruptive populations in beech-dominated forests in the South Island of New Zealand (King 1983, King andMoller 1997), as modeled by Blackwell et al (2001). Other studies have estimated higher peak abundances (e.g., Ruscoe et al 2001). In addition, possum numbers were required to peak at 50 individuals/100 ha (Cowan 1990).…”

Potential for camera-traps and spatial mark-resight models to improve monitoring of the critically endangered West African lion (Panthera leo)

“…In addition, the precision of such estimates can be poor, resulting in large intervals of possible abundances, which can hinder their use in assessing population status and trends. Despite these problems, monitoring of carnivores in Africa still often relies on attempts to locally calibrate counts or indices (Funston et al 2010;Thorn et al 2010;Bauer et al 2014;Henschel et al 2014;Midlane et al 2015), even though there is a strong record of failure with track index validation for multiple species across many regions (Ruscoe et al 2001;Blackwell et al 2002;Jhala et al 2011;Karanth et al 2011;Katzner et al 2011;Watts et al 2011;Sollmann et al 2013a), and especially for carnivores with typically very low detection rates . In Africa in particular, track indices are considered ineffective at estimating absolute abundance (Balme et al 2009;Biodivers Conserv Thorn et al 2010).…”

Predation on native birds in New Zealand beech forests: the role of functional relationships between Stoats Mustela erminea and rodents

“…In three Nothofagus forests in the South Island of New Zealand (described by King 1983), the masting years of 1976 and 1979 stimulated an increase in feral House Mice over winter. In one of these three areas, the Eglinton Valley, a seedfall in 1990 was described by Murphy and Dowding (1995), and another in 1999 by Ruscoe et al . (2001).…”