The influence of weather and moon phase on small mammal activity

Abstract

Small mammals are commonly surveyed using live trapping but the influence of weather conditions on trap success is largely unknown. This information is required to design and implement more effective field surveys and monitoring. We tested the influence of weather and moon phase on capture rates of small mammals in the Murray Mallee region of semi-arid Australia. We used extensive pitfall trapping data collected at 267 sites, totalling 54492 trap-nights. We built regression models to explore the relationship between the capture rates of five species and daily meteorological conditions, and across families of mammals, including dasyurids, burramyids and rodents. A relationship common to several taxa was the positive influence of high winds (>20km h−1) on capture rates. We also identified differences between taxa, with warmer overnight temperatures increasing capture rates of mallee ningaui but decreasing those of Bolam’s mouse. This makes it difficult to determine a single set of ‘optimal’ meteorological conditions for surveying the entire community but points to conditions favourable to individual species and groups. We recommend that surveys undertaken in warmer months encompass a variety of meteorological conditions to increase capture rates and provide a representative sample of the small mammal community present in a landscape.

Optimising camera trap surveys for the Carpentarian Pseudantechinus (Pseudantechinus mimulus) in northwest Queensland

“…While a range of mammalian taxa, including some small dasyurids, are known to exhibit changes in activity under varying levels of illumination (Hernandez-Santin & Fisher, 2022;Lindley et al, 2021;Prugh & Golden, 2014;Senior et al, 2021), we did not find any significant change in detection rates for P. mimulus as a result of lunar illumination. This is consistent with findings from several other small dasyurids that also show no effect of illumination on activity (Read, 1988;Sutherland & Predavec, 1999).…”

Moonlight and predation risk: does vegetation cover mediate the behaviour of small mammals and their predators?

“…For example, while Bolam's mouse (Pseudomys bolamii), mallee ningaui (Ningaui. yvonneae) and verreaux mouse (Praomys verreauxii) all responded negatively to moonlight 17,32 , several critical weight range (35-5500 g) prey species in a reintroduced mammal community did not respond to moonlight 33 . In this latter case a potential explanation was reduced predation pressure, as the study was conducted in a fenced area that excluded introduced vertebrate predators.…”

“…Both wind and precipitation may in uence predation risk by interfering with the auditory and olfactory cues of either predator or prey. For example, high wind speed has been found to have a positive in uence on capture rates of small mammals as the wind noise may mask their movement, decreasing predation risk 32 . Disentangling the interacting in uences of weather, cloud cover and moon illumination is challenging and will require manipulative experiments to tease apart their effects.…”