Drones are now coming to the aid of wildlife conservationists who aim to properly study and understand the potential influence of environmental change on wildlife populations.
A recent study jointly conducted by Australian CSIRO Health and Biosecurity and the School of Life and Environmental Sciences, Deakin University for studying the parameters of the Australian fur seals made use of unmanned aerial vehicle (UAV) obtained images successfully. The study was facilitated by logistical support from Parks Victoria and Best Helicopters and also by several volunteers and students who assisted with the collection of animal measurements in the field. The study was aimed at validating the use of UAVs as a means of measuring the relative index of body condition in otariid seals.
Representative image obtained via UAV (Parrot Sequoia) of Australian fur seals showing measurements of standard length (SL) and axillary width (AW, used to estimate axillary girth) on an adult female (a) and a 3–4 month old pup (b).
Indices correlating to parameters like body lipid content with mass and morphometric measurements of a variety of species form the basis of such studies. The main challenges in using live samples of any large species in nature are- firstly it is not logistically feasible to capture and handle enough animals to obtain representative population estimates and so the next challenge is to obtain sufficient quantities of high quality imagery (i.e., correct aspect, no visual obstructions) without disturbing the target subjects. This is where drone Photogrammetry pitches in and has been successfully used to measure size and estimate condition in several large mammal species.
Both these challenges are more than effectively met by the relatively low cost and reduced disturbance effects of UAVs making them ideal for the rapid acquisition of high volume data for monitoring large species.
This study examined the imagery collected from two different UAVs, flown at 25 m altitude, and the subsequent georeferenced orthomosaics as a method for measuring length and auxiliary girth of Australian fur seals to derive an index of body condition. The UAV-obtained images succeeded in obtaining measurements on sufficient numbers of animals lying in the sternal recumbent position.
In terms of challenges in using the UAVs there is always the risk of wind speeds becoming greater 15 k which are unsuited for UAV data collection. In fact during in the present study ideal conditions were met only approximately 40% of days at the colony. Additionally there could exist civil aviation and/or wildlife disturbance regulations specific to some locations that might prevent the use of UAVs at seal colonies.
The success in the use of UAV for this particular study however successfully demonstrated a rapid, minimally disruptive means of measuring a relative index of body condition in potentially large numbers of seals. The relatively inexpensive availability of UAVs and their ease of use make such data collection on a regular basis feasible for researchers and wildlife managers. The study recommends conduct of additional trials to assess the accuracy of measurements obtained via UAV for animals in different postures.