Rainfall decrease and red deer rutting behaviour: Weaker and delayed rutting activity though higher opportunity for sexual selection.

Antonio Flores,Cristina B Sánchez-Prieto,Juliana Valencia,Susana Alarcos,Javier Pérez-González,Jose M Seoane,Jerónimo Torres-Porras,Eva De La Peña,Juan Carranza,Marina F Millán,Leticia Castillo,Alberto Membrillo,Marco Apollonio

doi:10.1371/journal.pone.0244802

Antonio Flores, Cristina B Sánchez-Prieto + Show 11 more

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https://doi.org/10.1371/journal.pone.0244802

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Abstract

In the last decades, climate change has caused an increase in mean temperatures and a reduction in average rainfall in southern Europe, which is expected to reduce resource availability for herbivores. Resource availability can influence animals' physical condition and population growth. However, much less is known on its effects on reproductive performance and sexual selection. In this study, we assessed the impact of three environmental factors related to climate change (rainfall, temperature and vegetation index) on Iberian red deer Cervus elaphus hispanicus reproductive timing and sexual behaviour, and their effects on the opportunity for sexual selection in the population. We measured rutting phenology as rut peak date, the intensity of male rutting activity as roaring rate, and the opportunity for sexual selection from the distribution of females among harem holding males in Doñana Biological Reserve (Southwest Spain), from data of daily observations collected during the rut over a period of 25 years. For this study period, we found a trend for less raining and hence poorer environmental conditions, which associated with delayed rutting season and decreased rutting intensity, but that appeared to favour a higher degree of polygyny and opportunity for sexual selection, all these relationships being modulated by population density and sex ratio. This study highlights how climate change (mainly rainfall reduction in this area) can alter the conditions for mating and the opportunity for sexual selection in a large terrestrial mammal.

Highlights

Environmental factors strongly influence many elements of ecology and behaviour of organisms, including reproductive strategies and associated selective processes [1,2,3,4,5,6,7]
Variations in roaring intensity and rutting phenology over the 25 years of study suggest the influence of ambient and population factors producing pluriannual trends, which deserve attention to identify their causes and to the eventual prevention of their consequences
Our analyses have identified significant effects of three environmental variables on the rut intensity and phenology, and on the opportunity for sexual selection in the population

Summary

Introduction

Environmental factors strongly influence many elements of ecology and behaviour of organisms, including reproductive strategies and associated selective processes [1,2,3,4,5,6,7]. The red deer Cervus elaphus is a large mammal broadly distributed throughout Eurasia. For this species, the effects of climate change could be very different in northern and southern populations. A trend for red deer and other ungulates to reduce body size and fecundity in response to increasingly warm winters has been reported in Northern Europe [22, 23]. Regarding reproductive behaviour, red deer populations have been observed to shift breeding phenology in some Central (France) and Northern (Norway) European populations in response to climate variations. In the case of Mediterranean habitats of Southern Europe, very little is known about how climate change may affect red deer reproductive processes [28]

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