Food habit of the endangered yellow-spotted newt Neurergus microspilotus (Caudata, Salamandridae) in Kavat Stream, western Iran

Abstract

Diversity and abundance of macroinvertebrate fauna were simultaneously determined in selected benthic samples and in regurgitated stomach contents in Neurergus microspilotus in Kavat Stream (western Iran) during April and May 2012. The aim of this study was to determine the degree of reliance of this species to benthic macroinvertebrates during their reproductive season in aquatic habitat. Twenty-one taxa of macroinvertebrates were identified in the benthic samples while 19 taxa were presented in the regurgitated stomach contents. Data obtained from benthic samples showed that the most abundant macroinvertebrate groups included Lumbricidae (27.2%), Mycetophilidae (20.06%), Gammaridae (12.19%), and Plananariidae (9.3%). Data obtained from 45 stomach contents indicated that on average the highest importance values combining number, frequency, and volume for prey categories consumed included Mycetophilidae (14.03%), Baetidae (13.68%), Corbiculidae (12.57%), Gammaridae (10.8%), and Lumbricidae (9.34%). N. microspilotus also consumed small stones, plant materials, and their own eggs (0.91%). The analysis of selectivity in feeding using Ivlev’s index showed that the prey taxa that appeared to be preferred (E i > 0.5) were generally rare in the environment. Comparison between benthic macroinvertebrates and those taken by the newt demonstrates that although high similarity (Sorenson index of 78.94%) exists between the two communities, the dominance of the items taken by N. microspilotus (Simpson index = 0.32) is higher than that of the benthic community (Simpson index = 0.20) indicating that the newts rely on fewer number of species with higher proportion of individual prey items. Feeding habits of 45 N. microspilotus have shown that the newts rely extensively on Mycetophilidae, Baetidae, Corbiculidae, Gammaridae, and Lumbricidae as important food items for N. microspilotus.