Avian life history in the Anthropocene: a study of physiological, morphological, behavioural and fitness responses to rapid habitat change in an East African forest specialist (ANTHROBIRD).
Animal Physiology and Biochemistry
Sensory and Behavioural Biology
Final Report Abstract
Variation in environmental conditions across habitats has led to variation in life histories between species. To successfully reproduce and survive, an animal’s physiology, morphology and behaviour needs to be aligned to the environmental conditions of their habitat. Habitat fragmentation and degradation rapidly change abiotic and biotic properties of the environment and may disrupt the balance between life history traits. Especially in tropical areas – where species biodiversity, but also human population pressure, are highest - many pristine areas have been fragmented and degraded in the last decades. Habitat change imperils the persistence of numerous vertebrate species worldwide, but we are lacking knowledge about how habitat change affects social species, such as cooperative breeders, and tropical forest specialists. This study examines how fragmentation and degradation of the cloud forests of the Taita Hills, a biodiversity hotspot in Kenya, affects investment into reproduction and cooperative breeding in a tropical cooperatively breeding forest specialist, Phyllastrephus placidus, by studying its physiology and behaviour and relating it to forest structure and forest size. This study provides evidence that the forest fragments in the Taita Hills are still under pressure through subsistence use of the local communities that live near the forest. This has led to a simplified forest structure, such as reduced canopy and shrub cover, which in turn was correlated with a decreased arthropod abundance. Elevated baseline and stress-induced corticosterone levels of breeders and subordinates in small territories with low canopy cover indicate an increased workload during nestling provisioning which may be caused by lower arthropod prey availability. Reduced innate immune function (bacteria killing capacity) of nestlings, but not of adults, in small, degraded fragments suggests that parents may pass some of the costs of breeding in low quality territories on to their offspring. Similar to other tropical species, Placid greenbuls, have a slow life history, and are predicted to invest more into self-maintenance than into reproduction. Breeders can profit from cooperative breeding in several ways. For example, breeding females feed young less often, and breeders have a higher reproductive success when helped by subordinates. In addition, cooperative breeding may be especially advantageous in low quality territories, as breeders with subordinates at the nest had lower corticosterone levels than those with no subordinates when breeding in small forest fragments and territories with low canopy cover. It is less clear whether subordinates also benefit from group living in fragmented, degraded forest as offspring delayed dispersal less, i.e. stayed less time with their parents, than offspring from continuous forest. Thus, our data provide first evidence that the high behavioural flexibility of cooperative breeders may buffer against increased reproductive costs incurred in fragmented and degraded forests. However, reduced benefits for offspring to stay with their parents may potentially erode cooperation.
Publications
-
Maternal investment strategies of a cooperatively breeding forest specialist in degraded cloud forest fragments
Apfelbeck, B., Van de Loock, D., Cousseau, L., Githiru, M., Matthysen, E. & Lens, L.
-
Brutstrategien des Keniabülbüls. Gefiederte Welt 07/2020
Apfelbeck, B.
-
Habitat fragmentation shapes natal dispersal and sociality in an Afrotropical cooperative breeder. Proceedings of the Royal Society B: Biological Sciences, 287(1941), 20202428.
Cousseau, Laurence; Hammers, Martijn; Van de Loock, Dries; Apfelbeck, Beate; Githiru, Mwangi; Matthysen, Erik & Lens, Luc
-
Kin do not always help: testing multiple hypotheses on nest feeding in a cooperatively breeding bird. Behavioral Ecology, 33(6), 1080-1092.
Cousseau, Laurence; Van de Loock, Dries; Apfelbeck, Beate; Githiru, Mwangi; Matthysen, Erik & Lens, Luc
-
Contrasting effects of cooperative group size and number of helpers on maternal investment in eggs and nestlings. Animal Behaviour, 198, 107-116.
Van de Loock, Dries; Cousseau, Laurence; Apfelbeck, Beate; Githiru, Mwangi; Lens, Luc & Matthysen, Erik
