My research investigates cooperation in the natural world, with an emphasis on how cooperating impacts health and ageing. I have worked on several wild bird and mammal species and study a range of markers of animal health, including oxidative damage, antioxidant protection, and telomere length analysis. My PhD research with white-browed sparrow weavers demonstrated that the physiological costs of rearing young fall heaviest on those that breed most, but that these costs can be mitigated by cooperative sharing of workloads. In my first post-doctoral position, I showed that social dominance in cooperative groups of Kalahari meerkats is not associated with specialised slow ageing trajectories, and that sibling rivalries can accelerate ageing even in new-born pups.
My current focus is on the honeyguide’s contribution to the mutualistic foraging partnership with humans. After a successful harvest, the grateful honey-hunter typically leaves a piece of beeswax to reward the bird that guided them to the bees. However, our observations indicate that other honeyguides often eat this wax. If honeyguides can steal wax without guiding, how is the mutualism maintained? Which individual honeyguides cooperate with human honey-hunters, and which instead try to ‘scrounge’ a free meal? Are some honeyguides better guides than others? Do honeyguides that cooperate have access to more beeswax?
To address these questions, I have established a ringed population of honeyguides which allows us to collect individual-based data on decisions to guide or scrounge, guiding outcomes, and wax consumption. I am combining observational and experimental field data with laboratory analyses including stable isotope diet reconstruction and telomere length analysis.
Selected recent publications:
(Please see Google Scholar for a full publication list)
- Cram, D., Monaghan, P., Gillespie, R., Dantzer, B., Duncan, C., Spence-Jones, H. & Clutton-Brock, T. 2018 Rank-related contrasts in longevity arise from extra-group excursions, not delayed senescence, in a cooperative mammal. Current Biology 28: 2934-2939.
- Cram, D., Monaghan, P., Gillespie, R. & Clutton-Brock, T. 2017 Effects of early-life competition and maternal nutrition on telomere lengths in wild meerkats. Proceedings of the Royal Society B: Biological Sciences 284: 20171383
- Cram, D., Blount, J. & Young A. 2015 The oxidative costs of reproduction are group-size dependent in a wild cooperative breeder. Proceedings of the Royal Society B: Biological Sciences 282: 20152031.