Sign surveys can be more efficient and cost effective than driven transects and camera trapping: a comparison of detection methods for a small elusive mammal, the numbat (

Abstract

Context. Determining the most efficient detection method for a target species is key for successful wildlife monitoring and management. Driven transects and sign surveys are commonly used to monitor populations of the endangered numbat (Myrmecobius fasciatus). Camera trapping is being explored as a new method. These methods were unevaluated for efficacy and cost for numbat detection.Aims. To compare efficacy and costing of driven transects, sign surveys and camera trapping for detecting numbats in the Upper Warren region, Western Australia.Methods. Seven repeat sign surveys and driven transects, as well as 4 months of camera trapping, were conducted concurrently at 50 sites along three transects. Numbat detection rates and costing of the three techniques were compared, and detection probabilities were compared between sign surveys and camera trapping.Key results. Numbat signs were detected during 88 surveys at 39 sites, exceeding camera trapping (26 detections at 13 sites) and driven transects (seven detections near five sites). The estimated probability for detecting a numbat or a sign thereof (at a site where numbats were present) ranged from 0.21 to 0.35 for a sign survey, and 0.02 to 0.06 for 7 days of camera trapping. Total survey costs were lowest for driven transects, followed by camera trapping and sign surveys. When expressed as cost per numbat detection, sign surveys were cheapest.Conclusions. Comparative studies of survey methods are essential for optimal, cost-effective wildlife monitoring. Sign surveys were more successful and cost effective than camera trapping or driven transects for detecting numbats in the Upper Warren region. Together with occupancy modelling, sign surveys are appropriate to investigate changes in occupancy rates over time, which could serve as a metric for long-term numbat monitoring.Implications. There is no 'best' method for wildlife surveys. Case-specific comparison of animal detection methods is recommended to ensure optimal methods. For the numbat population in the Upper Warren region, further studies are needed to improve numbat detection rates from camera trapping, and to test sign surveys in autumn (March to May), when surviving juvenile numbats have established their own territory and assumptions regarding population closure are less likely to be violated.

Power of faecal pellet count and camera trapping indices to monitor mammalian herbivore activity

“…a large number of plots were required to detect medium-large effect sizes for rabbit). Occurrence data from scat detections may be particularly useful for rare and elusive species (Seidlitz et al 2021). Some variation in the spatial and temporal trends detected by the different methods was evident, in line with work by Paton et al (2021), suggesting that they measure slightly different aspects of activity and are subject to different biases.…”

“…Selection of the most appropriate index can be informed by a formal evaluation of the efficacy and efficiency of candidate methods in the context of For full list of author affiliations and declarations see end of paper *Correspondence to: Naomi E. Davis School of BioSciences, The University of Melbourne, Vic. 3010, Australia Email: Naomi.Davis@parks.vic.gov.au management objectives and resources (Garden et al 2007;Månsson et al 2011;Swan et al 2014;Seidlitz et al 2021).…”

“…Compared to a number of traditional methods, camera traps are relatively effective at detecting mammal species (Silveira et al 2003;De Bondi et al 2010;Paull et al 2012;Swan et al 2014;Wearn and Glover-Kapfer 2019), and are increasingly used for population monitoring (Karanth et al 2004;Nichols et al 2011). Importantly however, camera trapping does not always outperform traditional survey methods, providing lower or similar probabilities of detection and estimates of species richness and composition for some faunal groups (Silveira et al 2003;Gompper et al 2006;Espartosa et al 2011;Seidlitz et al 2021). Camera trapping also requires a substantial investment in equipment (Silveira et al 2003) and time for post-processing of data (Latham et al 2012) compared to traditional methods such as pellet counts.…”

Remote sensor camera traps provide the first density estimate for the largest natural population of the numbat (Myrmecobius fasciatus)

“…Numbat densities derived from camera trapping and SECR modelling may be suitable as the standard method by which all numbat populations are assessed and monitored. Density estimates can be derived from distance sampling applied to detections from driven transects (Vieira et al 2007), but low sighting rates in the Upper Warren suggest this is an inefficient method of sampling (Seidlitz et al 2021). Advantages over the driven transect approach include being able to record adequate numbers of animals, even in habitats with relatively high vegetation density, and may be more cost effective per numbat detection (Seidlitz et al 2021).…”

Comparing the effectiveness of camera trapping, driven transects and ad hoc records for surveying nocturnal mammals against a known species assemblage

“…scat, tracks or hair) of single species rather than other direct survey methods (e.g. wildcat (Felis silvestris silvestris) scat on Etna Volcano, Italy (Anile et al 2014); hair tubes and scat for pine martens in central Italy (Martes martes) (Bartolommei et al 2013); and sightings, fresh diggings and scat for numbats (Myrmecobius fasciatus) in Western Australia (Seidlitz 2021)). Other studies have compared assemblages of species, such as medium-sized ground-dwelling mammals using hair tubes in Australia (Paull et al 2012) and carnivore communities using track plates, scats and tracking in New York forests (Gompper et al 2006).…”