Using multiple methods to assess detection probabilities of forest‐floor wildlife

Abstract

Many previous comparisons of multiple sampling methods have assumed that detection probabilities for each method are either constant or equal to one. We used 4 sampling methods to estimate detection probabilities for forest-floor dwelling amphibians, reptiles, and small mammals. We investigated associations between seasonality and precipitation on species detection and explored sample design tradeoffs for future studies. Although we captured 25 species, we could reliably detect (detection probability >0.15) only northern short-tailed shrews (Blarina brevicauda) and pygmy and masked shrews (Sorex spp.) using drift fences and red-backed salamanders (Plethodon cinereus) using visual encounter surveys (VES). The use of multiple sampling methods improved detection probabilities for only red-backed salamanders (p VES ¼ 0.32, 95% CI: 0.24-0.38,p allmethods ¼ 0.38, 95% CI: 0.32À0.44). Parameter estimates indicated detection of both shrew species was positively related to increased precipitation. Detection probabilities for pygmy and masked shrews and red-backed salamanders were positively and negatively associated with date, respectively. Our power analysis revealed that sampling during rain events increased the power of detecting a change in sorid occupancy by !40% (a ¼ 0.05). Our results demonstrate the need to incorporate species detectability when comparing the effectiveness of different trapping methodologies. Furthermore, our study highlights the utility of power analyses for exploring study design tradeoffs for research and monitoring programs. ß 2011 The Wildlife Society.

Effects of Cover Board Age, Season, and Habitat on the Observed Abundance of Eastern Red-Backed Salamanders (Plethodon Cinereus)

“…Smith, unpubl. data), and is consistent with other studies of P. cinereus activity in northern parts of its range (e.g., DeGraaf and Yamasaki, 2002;Leclair et al, 2008;Otto and Roloff, 2011). Nagel (1977) showed that P. cinereus populations in the southernmost part of the species' range are active for most of the year with only a short inactive period during the summer, suggesting a single extended activity period rather than a bimodal pattern each year.…”

“…The effective use of terrestrial salamanders as ecological indicators depends on whether or not the data being collected is accurate and repeatable. Some of the more common methods of monitoring terrestrial salamanders have been the use of transect counts, quadrat searches, funnel traps, pitfall traps, searches of natural cover objects, and searches of artificial cover objects (Bailey et al, 2004;Strain et al, 2009;Otto and Roloff, 2011).…”

“…The effective use of terrestrial salamanders as ecological indicators depends on whether or not the data being collected is accurate and repeatable. Some of the more common methods of monitoring terrestrial salamanders have been the use of transect counts, quadrat searches, funnel traps, pitfall traps, searches of natural cover objects, and searches of artificial cover objects (Bailey et al, 2004;Strain et al, 2009;Otto and Roloff, 2011).The use of artificial cover objects has been suggested as a simple and efficient means of monitoring populations of plethodontid salamanders, particularly those of small-bodied terrestrial species such as the Eastern Redbacked Salamander (Plethodon cinereus) (Moore, 2005(Moore, , 2009Grover, 2006). Several factors influence the use of artificial cover objects by salamanders (see Miller Hesed, 2012 for review) including: the proximity of the artificial cover objects to natural cover objects (Ciul et al…”

Do biomass harvesting guidelines influence herpetofauna following harvests of logging residues for renewable energy?

“…Detection of herpetofauna can vary with large‐scale habitat characteristics (e.g., aspect and elevation), small‐scale habitat characteristics (e.g., nearby downed woody debris), environmental conditions (e.g., rain and temperature), and species (MacKenzie et al. , Otto and Roloff ). N ‐mixture models estimate population sizes from count surveys of unmarked animals while simultaneously accounting for imperfect detection (Royle ).…”

Comparing Population Patterns to Processes: Abundance and Survival of a Forest Salamander following Habitat Degradation

“…We used spatial, as opposed to temporal, replication for sampling salamanders because it minimized the number of repeated visits to each site and reduced travel between sites. Furthermore, previous work shows that temporally replicated cover object searches often violate the “closure” assumption of the state-space models we used for analysis [30], [33]. Each transect was surveyed once unless it was selected with replacement, in which case it was surveyed again 12–16 days later.…”