Dr Justin A. Welbergen

Tel: + 61 2 6125 4947
Fax: +61 2 6125 5573
Email: justin.welbergen and anu.edu.au

Justin Welbergen is now a Visiting Fellow at the Australian National University in Canberra.

Current research:

I am currently a post-doctoral Research Fellow, funded by the Natural Environment Research Council, working with Professor N. B. Davies FRS. Our research focuses on the role of learning in coevolution. In particular, we study how local knowledge may affect behavioural strategies in brood parasite-host systems. To date we have discovered that hosts, such as reed warblers Acrocephalus scirpaceus, treat cuckoos Cuculus canorus as a special enemy and defend their nests specifically against the brood parasites. They use mobbing as a frontline of defence that can be socially transmitted, and varied strategically according to local parasitism risk, which hosts assess by observing cuckoos directly and by indirect means. Host aggression is effective in reducing parasitism and has likely selected for Batesian mimicry of hawks by cuckoos. The general implications of our work were recently discussed in Current Biology (19, R170-R171).

I have been awarded a Research Grant from the Association for the Study of Animal Behaviour to conduct a pilot study into “mother guarding” using the cooperatively breeding noisy miner (Manorina melanocephala) as a model species. The study is based on the novel idea that offspring may benefit from protecting the paternity of their father, albeit sometimes against the best interests of their mother. In principle this should apply to all species in which offspring show delayed dispersal and where breeding pairs raise multiple broods or litters (i.e. as in many cooperatively breeding species). Because such species have traditionally served as model systems for the study of the evolution of the family, the idea potentially has important consequences for our understanding of family life, and it may push our understanding of the selective forces that shape social organisation into new directions.

In addition, I am collaborating with Dr Mike Brooke on a project that is investigating the population dynamics of the critically endangered Raso lark (Alauda razae). The species is one of the least known birds in the western Palearctic region. The Raso lark is restricted to a small, arid, uninhabited island (7km2 ) in the Cape Verde group, off the western coast of Africa. The tiny population size (~150 birds), together with a highly skewed male-biased sex-ratio make the survival of this species of real concern. The research is vital to developing a conservation strategy for the lark.

Finally, I am transforming my doctoral work (see below) into a longitudinal project, which would allow me follow up on several promising avenues of research and it would enable me to maintain and expand the stock of individually marked bats. The project would provide a good infrastructure for student projects, whether at PhD, Honours or 3rd year undergraduate levels, and this would enable me to further my teaching interests.

Reed Warbler feeding a Cuckoo fledgling (photograph by Artur and Saturnina Homan)


Noisy miner


Raso lark

PhD: The social organisation of the grey headed flying-fox, Pteropus poliocephalus

The grey-headed flying-fox is a placental mammal and is amongst of the largest species of bats. The species is endemic to south-eastern Australia, principally east of the Great Dividing Range. During the day it roosts in large aggregations in canopy trees and at night it forages for nectar, pollen and fruit. Very little was known about the social organisation of Pteropus spp., and information on the behaviour in colonies and at feeding sites was scant, a problem commonly encountered in this ecologically important group of animals.

For my PhD, I studied colony structure, activity timing and survival of the grey-headed flying-fox, and examined how flying-fox social organisation relates to underlying social, ecological and climatological factors. My study involved three long field seasons at colonies in the Tweed Shire in northern NSW, Australia (for more info see study area and sites). My primary field site contained 30.000 bats (both grey-headed flying-foxes and black flying-foxes) and was home to about 5 percent of the grey-headed flying-foxes left on the planet. My study was the first on Pteropus spp. to successfully implement a capture-mark-resighting methodology that allows for capture of specific individuals and for repeated behavioural sampling of the same individuals between locations and across years. In my thesis, I showed that the social organisation of P. poliocephalus is very complex and driven by an interplay of social, ecological, and climatic factors. For example, I showed that colonies were partitioned geographically between individuals in terms of their age and sex, in terms of their physical quality, and in terms of their propensity to migrate. In addition, I showed that the timing of the evening emergence of bats from the colony was affected by weather and predation risk, and by social constraints. I found that temperature extremes can cause mass die-offs in flying-foxes, representing some of most dramatic cases of mass mortality ever recorded in mammals. These events have disproportionate effects on social organisation in the colonies through their impact on the effective breeding population and recruitment – two key parameters for conservation.