Detecting small and cryptic animals by combining thermography and a wildlife detection dog

Denise Karp

doi:10.1038/s41598-020-61594-y

Abstract

Small and cryptic species are challenging to detect and study in their natural habitat. Many of these species are of conservation concern, and conservation efforts may be hampered by the lack of basic information on their ecological needs. Brown hare (Lepus europaeus) leverets - one example of such a small, cryptic and endangered animal - are notoriously difficult to detect, and therefore data on wild leverets are virtually non-existent. Novel technologies and methods such as thermal imaging and the use of wildlife detection dogs represent suitable means for the detection of such species by overcoming the problem of camouflage, using heat or scent emission respectively. Our study on brown hare leverets provides information on how to apply these new techniques successfully for the detection of small and cryptic species, thus enabling the collection of data that was previously inaccessible (e.g. behavioural observation, radio tagging). We found that the choice of method should be made according to vegetative structure. While the handheld thermal imaging camera is best used in areas with no or low vegetative cover, the thermal drone can be used up to medium vegetative cover, whereas the detection dog method is best applied where vegetation is very dense and not suitable to be searched using thermography. Being able to search all sort of different vegetation types, our combined approach enables the collection of a balanced and unbiased dataset regarding habitat type and hence selection of study specimen. We hope that the use of these new techniques will encourage research on many cryptic species that formerly have been neglected because they could not be detected using conventional methodologies.

Highlights

Small and cryptic species are challenging to detect and study in their natural habitat
Many animal species show a form of crypsis – the ability to minimize detection by other animals – either to avoid being predated or to avoid detection by potential prey[1]
Predator avoidance is especially important for dependent offspring, and the young of many species are exceptionally well camouflaged[3]. Due to their cryptic and elusive nature, these highly camouflaged animals can represent a considerable challenge for researchers to detect and study[4]. Many of these cryptic species are classified as being threatened and conservation efforts often are restrained by the lack of basic information on their ecological needs[5,6]

Summary

Introduction

Small and cryptic species are challenging to detect and study in their natural habitat. Our study on brown hare leverets provides information on how to apply these new techniques successfully for the detection of small and cryptic species, enabling the collection of data that was previously inaccessible (e.g. behavioural observation, radio tagging). Predator avoidance is especially important for dependent offspring, and the young of many species are exceptionally well camouflaged[3] Due to their cryptic and elusive nature, these highly camouflaged animals can represent a considerable challenge for researchers to detect and study[4]. Using the brown hare leveret (Lepus europaeus) as a representative for small and cryptic animals, we describe the pros and cons of using thermography (handheld and airborne) and a wildlife detection dog to detect cryptic wildlife Their lack of motion during most of the day, small size, and cryptic fur coat make leverets visually merge with the background. This is the case for hares, where increased postnatal mortality has been identified as an important factor explaining the decline of brown hare populations in Europe[28,29]

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Discussion

Conclusion