Stop and ask for directions: factors affecting anuran detection and occupancy in Pampa farmland ponds

Abstract

There is a great need to understand the effects of man‐made land transformation on freshwater biodiversity, because agricultural landscapes provide habitat for many aquatic and semi‐aquatic organisms. However, not all forms of land use are equal in their capacity to support wildlife. Cattle grazing leads to a change in pasture vegetation structure, whereas conversion to commercial crop‐based agriculture promotes structural and chemical degradation of the ecosystem. From 2010 to 2012, in the Pampa biome, southern Brazil, we modelled anuran occupancy for 39 farmland ponds. Specifically, we determined detection probabilities associated with survey‐ and pond‐specific variables and examined tadpole occupancy in relation to land use in southern Brazil. We recorded eleven anuran species, but only five were detected at levels suitable for occupancy modelling. Species detectability varied with water temperature, extent of floating macrophyte cover, and sampling date. For three species, detection‐adjusted occupancy models indicated a relationship between occupancy and agricultural activities and/or livestock management. Agriculture areas negatively affected occupancy by Odontophrynus americanus and Physalaemus gracilis. The presence of livestock within a 500 m radius positively affected pond occupancy by Hypsiboas pulchellus. Other species were negatively associated with pond area or fish presence. Our results demonstrate that traditional extensive livestock farming can provide a buffer that protects freshwater environments, because it did not greatly modify the grassland matrix. We argue that further species‐based approaches will be critical for developing effective conservation strategies for anurans, particularly in the context of the expanding rice production/exotic forests in southern Brazil.

Population trend inferred from aural surveys for calling anurans in Korea

“…Advertisement calls of D. suweonensis and D. japonicus are species specific ( Jang et al, 2011 ; Park, Jeong & Jang, 2013 ) and are suitable for field surveys even to untrained ears ( Roh, Borzée & Jang, 2014 ; Borzée et al, 2015 ; Borzée et al, 2017b ). In calling Hylids, acoustic monitoring is used to estimate population sizes ( Weir et al, 2005 ; Pellet, Helfer & Yannic, 2007 ; Dorcas et al, 2009 ; Petitot et al, 2014 ; Moreira, Moura & Maltchik, 2016 ), and the aural survey protocol followed here is accurate to estimate occurrence ( Borzée et al, 2017a ; Borzée et al, 2017b ). However, population surveys of closely related calling Hylid species have demonstrated that most individuals are detected within two minutes of survey ( Petitot et al, 2014 ; Corn et al, 2011 ).…”

Preliminary Analysis of the Diet of Triturus carnifex and Pollution in Mountain Karst Ponds in Central Apennines

“…The controversial impact of grazing on amphibians' communities is still debated, as reviewed by Howell, Mothes, Clements, Catania, Rothermel and Searcy [29]; some studies highlighted the negative effects of grazing on amphibians, e.g., [60,61], while others documented a positive or intermediate response, due to the species-specific requirements of the target amphibians [62][63][64].…”

Amphibians of northwestern Buenos Aires province, Argentina: checklist, range extensions and comments on conservation

“…However, we cannot dismiss the fact that the agricultural practices taking place in the Inland Pampas (causing habitat loss and aquatic contamination) may have influenced amphibian diversity in recent years. Several studies have reported that agricultural impacts can lead to the impoverishment of biological communities, reflected by the loss of the most sensitive species (Peltzer et al 2006;Agostini et al 2013;Moreira et al 2016). In this regard, it is important to highlight that species richness is higher in eastern Buenos …”