Nest site selection and nesting behavior of the mud turtle Kinosternon scorpiodes (Testudines, Kinosternidae) in Palo Verde National Park, Costa Rica: implications for management

Franklin E Castañeda,José M Mora

doi:10.3897/neotropical.16.e60754

Abstract

Habitat selection is the process whereby individuals preferentially use, or occupy, a non-random set of available habitats. At the same time, nest site selection is defined as the placement of eggs by females at sites differing from random sites within a delimited area. We located 59 nests of the mud turtle Kinosternon scorpioides in Palo Verde National Park (PVNP) in Northwestern Costa Rica. We compared eight microhabitat variables at nest sites against those at random sites. Females significantly placed their eggs at sites with more understory, leaf litter cover, and greater leaf litter depth than in random sites. Additionally, females selected sites with lower air and soil temperature and lower air humidity. Palo Verde NP is subject to active management actions designed to control invasive plant species in the wetland, namely cattail (Thypha domingensis Pers.). The main actions have been cattle grazing, controlled fires, and mechanical crushing of vegetation. We found that habitat quality in nesting areas is being threatened by at least one of these actions: cattle grazing. This is detrimental for three microhabitat traits that turtles select for nesting sites: understory cover, leaf litter cover, and leaf litter depth. The continued degradation of microhabitats at nesting areas of K. scorpioides at PVNP could be affecting recruitment due to embryo survivorship.

Highlights

Variation in abundance and distribution of a species is often determined by suitable habitat availability, which must include all necessary components to ensure the species survival: food, water, refuge, and reproductive sites (Litvaitis et al 1994)
We found that average carapace length (CCL) of nesting Kinosternon scorpiodes at Palo Verde is higher than the most common size of 15 cm previously reported for this species (Rueda-Almonacid et al 2007)
We provide data on specific microhabitat traits that characterize nesting areas of K. scorpiodes at this park in Northwestern Costa Rica

Summary

Introduction

Variation in abundance and distribution of a species is often determined by suitable habitat availability, which must include all necessary components to ensure the species survival: food, water, refuge, and reproductive sites (Litvaitis et al 1994). Nest site selection is defined as the placement of eggs by females at sites with different characteristics from random sites within a delimited area (Wilson 1998). Such behavior may reduce both egg predation and exposure to environmental extremes (Wilson 1998) which leads to increased embryo development and survival rates. For turtles and many other animals, nest predation is a major cause of reproductive failure (Oddie et al 2015; Voves et al 2016), making nest site selection an important component of fitness. Maternal site selection represents a critical component of nest success (Mui et al 2016)

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Discussion

Conclusion