One of the cornerstones of life history theory is that there exists a trade-off between current and future reproduction. What that really means is that if you invest a lot into one breeding attempt you will have less available energy for future reproductive attempts or for your own self-maintenance (thereby possibly reducing lifespan). Famous rocker Neil Young once sang, “It’s better to burn out than to fade away” and in a way the whole point of this area of research is to understand if he was right or not (perhaps not for rock stars, where other things than lifetime reproductive success might be of greater importance).
In birds, one of the most common ways to investigate this trade-off is to manipulate brood size, thereby either making it easier or harder for parents to feed all their young. The golden standard for such studies is to assume that work rate differs between parents with different brood sizes and even though there are studies that confirm this pattern the effects of such a manipulation seem to vary quite substantially between years and with other environmental factors.
Thus, we are missing one essential component in the puzzle, which is: how is feeding frequency (work rate) truly affected by brood size manipulations?
This question has been answered before, but only using short snapshots in time, counting feeding events over hours and possibly a few days. However, to understand the full effect of brood size manipulations on parental investment and work rate we need to know the energy spent throughout the full nestling period. Work rate is not a constant trait and varies over time as nestlings grow older and there could be differences in these patterns, according to brood size.
You will conduct the fieldwork in the period April-June in a population of nest-box breeding blue tits (Cyanistes caeruleus) in the scenic landscape surrounding Lake Krankesjön, circa 20 km east of Lund. You will get hands-on experience of capturing, handling, and ringing birds and the possibility to work with multiple techniques involved in measurement of feeding frequency and possibly also other areas of research. To get the most out of the project, it would be advantageous to have some prior experience of handling birds, and a driver’s license is required to be able to conduct the field-work. This is a project that can be modified and suited to your own interests – it would for example be easy to add other components into this framework (i.e. phenology, immunology, body temperature regulation etc.) – so please contact me, should you find this topic interesting.
https://portal.research.lu.se/en/persons/fredrik-andreasson