Early and late fawn mortality in a remnant population of Arabian gazelles (Gazella arabica)

Benny Shalmon,Torsten Wronski,Ping Sun

doi:10.1007/s42991-021-00162-x

Abstract

The Arabian gazelle (Gazella arabica) population in Israel has experienced a turbulent conservation history and repeatedly faced local extinction. Low fawn survival was considered the main cause for the constant decline. In our study, we analyzed instantaneous fawn mortality rates, using a binomial coding at three different developmental stages, i.e., mortality rates to 3 months after parturition (weaning age), to 5 months after parturition (male fawns leave their mothers), and to the age of reproductive maturity, i.e., recruitment (12 months). We used a dataset obtained from 20 individually discernible mothers and their fawns (49 females and 48 males) born between June 2006 and September 2019. To explore causes for the fawn mortality rates, parental- (age of the mother at parturition) and offspring-related attributes (offspring sex), year of birth, together with one weather variable (mean monthly maximum temperature) were included as independent variables into three independent mixed effects cox regression models. Out of 97 fawns, 92 survived to weaning age, 73 to the age of 5 months and only 7 to the age of reproductive maturity. Temperature had significant effects on instantaneous fawn mortality rates, suggesting that low temperatures were detrimental to the survival of fawns after weaning (4–5 months) and male dispersal age (6–12 months). Male offspring encountered a higher instantaneous mortality rate than female offspring at the age of 6–12 months. Moreover, fawns from less experienced mother (young age at parturition) experienced higher mortality. Our results were in line with previous studies on fawn mortality observed in other desert dwelling ungulates.

Highlights

The scientific monitoring of population dynamics plays a vital role in wildlife management, for threatened and endangered desert ungulates
We evaluated how two other factors potentially influencing population decline of Arabian gazelles—mothers experience and weather—affected juvenile recruitment, a demographic rate known to have high influence on ungulate population dynamics (Gaillard et al 2000)
While Shalmon et al (2020) referred to an annual cycle, this study focused on monthly instantaneous fawn mortality rates using the life history data of 20 mothers and their fawns and relating them to monthly weather data that directly followed each birth

Summary

Introduction

The scientific monitoring of population dynamics plays a vital role in wildlife management, for threatened and endangered desert ungulates. Their study suggested a strong impact of wolf predation on the gazelle population and a moderate effect of climate on fawn mortality, while competition and resource availability played only a minor role (but see Breslau et al 2019).

Results

Conclusion