Life history differences influence the impacts of drought on two pond‐breeding salamanders

Abstract

Drought is a strong density-independent environmental filter that contributes to population regulation and other ecological processes. Not all species respond similarly to drought, and the overall impacts can vary depending on life histories. Such differences can necessitate management strategies that incorporate information on individual species to maximize conservation success. We report the effects of a short-term drought on occupancy and reproductive success of two pond-breeding salamanders that differ in breeding phenology (fall vs. spring breeder) across an active military base landscape in Missouri, USA. We surveyed ;200 ponds for the presence of eggs, larvae, and metamorphs from 2011 to 2013. This period coincided with before, during, and after a severe drought that occurred in 2012.The two species showed contrasting responses to drought, where high reproductive failure (34% of ponds) was observed for the spring breeder during a single drought year. Alternatively, the fall breeder only showed a cumulative 8% failure over two years. The number of breeding ponds available for use in the fall decreased during the drought due to pond drying and/or a lack of re-filling. Estimates of occupancy probability declined for the fall-breeding salamander between 2012 and 2013, whereas occupancy probability estimates of the spring breeder increased post-drought. The presence of fish, hydroperiod, the amount of forest cover surrounding ponds, and canopy cover were all found to affect estimates of occupancy probabilities of each species. Pond clustering (distance to nearest pond and the number of ponds within close proximity), hydroperiod, forest cover, and canopy cover influenced both estimates of colonization and extinction probabilities. Our results show life history variation can be important in determining the relative susceptibility of a species to drought conditions, and that sympatric species experiencing the same environmental conditions can respond differently. Consideration of the spatial network and configuration of habitat patches that act as refuges under extreme environmental conditions will improve conservation efforts, such as the placement of permanent ponds for aquatic organisms. A better awareness of species-specific tolerances to environmental filters such as drought can lead to improved management recommendations to conserve and promote habitat for a greater diversity of species across landscapes of spatially connected populations.

Automated analysis of temperature variance to determine inundation state of wetlands

“…Babbitt et al 2003;Babbitt 2005;Anderson et al 2015). The actual number of drying and filling events, as well the actual length of days a wetland holds water can be predicted using our methods, which will improve our understanding of the sensitivity of different species to temporal regimes of inundation.…”

Manipulating waterbody hydroperiod affects movement behaviour and occupancy dynamics in an amphibian

“…Our analyses found that colonisation more frequently results in effective breeding in plastic containers than in other waterbodies. Yet such a strategy results in frequent breeding failure (Anderson et al, 2015;Green et al, 2013;Hartel et al, 2011). Moreover, inter-annual abandonment of a waterbody by breeding adults is lower in plastic containers than in other waterbodies.…”

“…Altermatt & Ebert, 2008, 2010Bates, Sadler, & Fowles, 2006). In these organisms, breeding success is strongly impacted by waterbody desiccation and intraspecific competition at the larval stage (Anderson, Ousterhout, Peterman, Drake, & Semlitsch, 2015;Green, Hooten, Grant, & Bailey, 2013;Hartel, Bancila, & Cogalniceanu, 2011;Van Buskirk & Smith, 1991;Wilbur, 1976). Pond-breeding amphibians are excellent biological models to fill this gap.…”

Using spatial demographic network models to optimize habitat management decisions

“…At each site, each year, we conducted 3 independent dip net surveys, and typically 3 trapping sessions (ponds surveyed = 139, 169, and 151 in 2012, 2013, and 2014, respectively), although we excluded some sites from trapping because of their location (e.g., roadbed ditch) or shallow water depth ( n = 18, 24, and 31 in 2012, 2013, and 2014, respectively). Previous analyses with these data reported that detection did not vary by sampling method (Peterman et al , Anderson et al ). We therefore included all sites surveyed in analyses regardless of whether we used funnel traps.…”

“…The reasons for ringed salamanders failing to breed in nearly half of the wetlands in the Focal Area are varied, and are unknown in many cases. The presence of fish and short or ephemeral hydroperiods are 2 of the primary reasons that ringed salamanders fail to breed or successfully recruit from a pond (Peterman et al , Anderson et al , Semlitsch et al ), both of which can be modified through direct management (Walston and Mullin , Calhoun et al ). It is important, however, to carefully assess all relevant structural habitat features to ensure that restoration efforts provide more than partial remediation.…”