Synergistic effects of seasonal rainfall, parasites and demography on fluctuations in springbok body condition
Article first published online: 10 AUG 2011
© 2011 The Authors. Journal of Animal Ecology © 2011 British Ecological Society
Journal of Animal Ecology
Volume 81, Issue 1, pages 58–69, January 2012
How to Cite
Turner, W. C., Versfeld, W. D., Kilian, J. W. and Getz, W. M. (2012), Synergistic effects of seasonal rainfall, parasites and demography on fluctuations in springbok body condition. Journal of Animal Ecology, 81: 58–69. doi: 10.1111/j.1365-2656.2011.01892.x
- Issue published online: 8 DEC 2011
- Article first published online: 10 AUG 2011
- Received 11 January 2011; accepted 1 July 2011 Handling Editor: John Fryxell
- Etosha National Park;
1. Seasonality of rainfall can exert a strong influence on animal condition and on host–parasite interactions. The body condition of ruminants fluctuates seasonally in response to changes in energy requirements, foraging patterns and resource availability, and seasonal variation in parasite infections may further alter ruminant body condition.
2. This study disentangles the effects of rainfall and gastrointestinal parasite infections on springbok (Antidorcas marsupialis) body condition and determines how these factors vary among demographic groups.
3. Using data from four years and three study areas, we investigated (i) the influence of rainfall variation, demographic factors and parasite interactions on parasite prevalence or infection intensity, (ii) whether parasitism or rainfall is a more important predictor of springbok body condition and (iii) how parasitism and condition vary among study areas along a rainfall gradient.
4. We found that increased parasite intensity is associated with reduced body condition only for adult females. For all other demographic groups, body condition was significantly related to prior rainfall and not to parasitism. Rainfall lagged by two months had a positive effect on body condition.
5. Adult females showed evidence of a ‘periparturient rise’ in parasite intensity and had higher parasite intensity and lower body condition than adult males after parturition and during early lactation. After juveniles were weaned, adult females had lower parasite intensity than adult males. Sex differences in parasitism and condition may be due to differences between adult females and males in the seasonal timing of reproductive effort and its effects on host immunity, as well as documented sex differences in vulnerability to predation.
6. Our results highlight that parasites and the environment can synergistically affect host populations, but that these interactions might be masked by their interwoven relationships, their differential impacts on demographic groups, and the different time-scales at which they operate.