Comparison of population estimators and indices for monitoring house mice in sorghum crops

Abstract

House mice (Mus musculus domesticus Schwarz & Schwarz, 1943) are monitored in Australia and China to track changes in mouse population densities and forecast their potential damage to cereal crops. The present study compared population indices based on the number of different mice caught and overall trap success from live-trapping with an oil card index (OC) and a tracking index (T) for monitoring mice in sorghum crops immediately before crop maturation. T was measured as the percentage of track board covered with mouse footprints night(-1), and OC as the percentage of card removed by mice night(-1). The reliability of these abundance indices was quantified by Pearson correlation coefficient with the trappable population size (Ñ), which was estimated by capture-recapture over eight consecutive nights on 175 × 5 trapping grids, in sorghum crops on two properties on the Darling Downs, Queensland. Because of differences among individual mice in capture probability, Model M(h) of program MARK was used to account for such heterogeneity and to estimate the size of each mouse population. The number of individual animals caught was more strongly correlated with Ñ than trap success and, therefore, might be a more reliable index; the data suggest that three trapping occasions provide optimal precision for this index. T correlated significantly with Ñ only at sites where the canopy of sorghum plants was closed, and its use should, therefore, be restricted to this habitat. OC did not correlate with Ñ because none or very little of the cards was eaten at low to moderate mouse densities. T and the number of animals caught over three trapping nights are recommended for monitoring mice in sorghum crops immediately prior to crop maturation.

Population dynamics of house mice in Queensland grain-growing areas

“…The data also came from only a single-night trapping at each site along the transects. This is considered unreliable because of the night-to-night variation in trap success for house mice observed in other studies (Davis et al 2003;Kaboodvandpour et al 2010). Although this could be a problem at a local scale of a single farm (i.e.…”

It’s a trap: effective methods for monitoring house mouse populations in grain-growing regions of south-eastern Australia

“…Many approaches and analytical methods require individual identification, such as, for example, using Program MARK (e.g. Kaboodvandpour et al 2010). We used ear punches to mark animals so that Petersen estimates could be determined.…”

“…However, this increases the effort required for estimating population abundance, to determine mouse damage risks to crops, and as input into forecast models. Kaboodvandpour et al (2010) found that the number of individual animals caught performed better as an index than did trap success, but that study was conducted only as sorghum crops were maturing, and thus the utility for year-round monitoring is unknown.…”

“…Furthermore, can observations from one location be applied to a broader region, such as, for example, similar grain farms 10, 100 or 1000 km away? Mouse chew cards have been used by several researchers (Mutze 1998;Brown et al 2004;Kaboodvandpour et al 2010), but only one example was found where active burrow counts were used (Mutze 1998). No systematic evaluations or comparisons of these indexes have been made with trapping indexes of abundance.…”