12 Jun 2018
Exploring the effect of an invasive lepidopteran on an endemic insectivorous bird

BRANTA — Cristiano Gala

Exploring the effect of an invasive lepidopteran on an endemic insectivorous bird

Institution: University of East Anglia (UEA), UK

Supervisors: Prof. David S. Richardson, Dr. Janske van de Crommenacker

Details: MSc, 2017

Via malcesine 64
Rome, 00135

Subject Keywords:invasive caterpillar, hairy caterpillar, island endemic, island ecosystem, bird, insectivore, lepidopteran pest
Species Keywords: Seychelles Warbler, Euproctis, Acrocephalus sechellensis


Endemic species all over the world are threatened by species introduction, habitat loss and climate change. Particularly on islands, predation, competition and trophic web disruption by invasive species have led to the extinction of many endemics. Insects, with high reproductive outputs and diverse anti-predator defences, are common invasive pests across different systems. Lepidopteran larvae, in particular, cause significant defoliation, and physical defences, such as urticating spines, pose a risk to humans and wildlife. In 2015 the invasion of an unidentified hairy lepidopteran moth species on islands of the Seychelles, caused concern for the rare endemic vertebrates and invertebrates resident on these islands. The Seychelles warbler (Acrocephalus sechellensis), as an endemic insectivorous passerine of high conservation concern, serves as a perfect model for understanding the impact of this lepidopteran on local fauna. I explore the interactions between this invasive species and A. sechellensis, by studying the behaviour, territory use and distribution of the warbler. The consequences of this invasion on body condition, territory quality and on the population as a whole have been explored as well. Individuals of A. sechellensis were seen feeding on adult moths but their behaviour did not seem altered by caterpillars. Infestation was not found to be significant enough for it to restrict A. sechellensis use of their territories. Furthermore high overlap in use of space was observed between the two species across the whole island. Infestation was not found to affect A. sechellensis’s body condition but a reduction in territory quality was found as infestation increased. The population as a whole is growing steadily and does not appear changed by the establishment of this invasive species. Continuous monitoring effort for both species with particular focus on the mechanisms underlying A. sechellensis’s potential habitat degradation by the lepidopteran is recommended for future work.

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