What can whiskers tell us about mammalian evolution, behaviour, and ecology?

Most mammals have whiskers; however, nearly everything we know about whiskers derives from just a handful of species, including laboratory rats Rattus norvegicus and mice Mus musculus, as well as some species of pinniped and marsupial. We explore the extent to which the knowledge of the whisker system from a handful of species applies to mammals generally. This will help us understand whisker evolution and function, in order to gain more insights into mammalian behaviour and ecology. This review is structured around Tinbergen’s four questions, since this method is an established, comprehensive, and logical approach to studying behaviour. We ask: how do whiskers work, develop, and evolve? And what are they for? While whiskers are all slender, curved, tapered, keratinised hairs that transmit vibrotactile information, we show that there are marked differences between species with respect to whisker arrangement, numbers, length, musculature, development, and growth cycles. The conservation of form and a common muscle architecture in mammals suggests that early mammals had whiskers. Whiskers may have been functional even in therapsids. However, certain extant mammalian species are equipped with especially long and sensitive whiskers, in particular nocturnal, arboreal species, and aquatic species, which live in complex environments and hunt moving prey. Knowledge of whiskers and whisker use can guide us in developing conservation protocols and designing enriched enclosures for captive mammals. We suggest that further comparative studies, embracing a wider variety of mammalian species, are required before one can make large-scale predictions relating to evolution and function of whiskers. More research is needed to develop robust techniques to enhance the welfare and conservation of mammals

Optimising the palatability and longevity of stoat baits

In New Zealand, introduced stoats (Mustela erminea) are significant predators of many native bird species. Trapping for stoat control is currently undertaken, but imposes logistical and cost constraints on the frequency and area over which their impacts can be mitigated. We sought to identify a highly acceptable stoat bait formulation with an extended field life that could be used for delivery of appropriate poisons. In feeding trials with wild-caught stoats, we screened 6 meat bases and > 20 humectant, preservative, binder or palatant compounds for acceptance and palatability. Significant differences in bait acceptance between female and male stoats were found. A humectant-preservative combination of polyethylene glycol (PEG 20,000) and sorbitol in rabbit mince was identified as optimal with over 80% acceptance by both male and female stoats and higher palatability (73.5%) than plain rabbit mince. This bait combination was acceptably ‘long-life’, with 80% of stoats eating PEG sorbitol bait weathered for 28 days. This bait formulation thus has useful application in current stoat trapping programmes but also potential in future delivery of selective poisons, such as para-aminopropiophenone, to manage field populations of stoats

The effect of colour on bait consumption of kea ( Nestor notabilis

The kea (Nestor notabilis), an endemic parrot, is at risk of primary poisoning during 1080 possum control operations. This project aimed at providing information on the effect of colour on bait attractiveness for kea to ultimately increase the safety of toxic bait. A feeding trial with captive kea investigated their colour preferences by offering cake dyed in six different colours simultaneously over six consecutive days. On average, the order of preference was yellow>red>brown>mid-blue>dark-blue>green; all birds encountered and consistently consumed less green bait than all the other colours throughout the trial. These results suggest that green is the most promising colour to deter captive kea from feeding in a multi-choice situation. However, due to kea's opportunistic feeding behaviour and inquisitive nature this might not be the case if green is the only option, suggesting that a stronger deterrent than colour may be necessary to deter free-ranging birds from consuming toxic bait