Trophic ecology of the endemic Azores Woodpigeon Columba palumbus azorica
- NameRémi Paul Fontaine
- Entity hostCIBIO – Centro de Investigação em Biodiversidade e Recursos Genéticos, InBio Laboratório Associado
- University awarding the degreeUniversity of Porto
The main goal of this project is to clarify the trophic relations between the Azores Woodpigeon and the plants of its insular environment, focusing on natural forests, exotic woodlands and cultivated fields. Our objectives are:
- Determine the Azores Woodpigeon’s diet and its spatio-temporal variation, by analysing non-invasive samples (faeces) collected on the islands of Pico and Terceira, during two years, using molecular and micro-histological methods.
- Assess food resource availability (including crop dynamics) by determining the diversity and relative abundance of food items available to the Azores Woodpigeon.
- Relate diet to food availability to describe the Azores Woodpigeon’s trophic ecology and evaluate food selection, habitat use and seasonal fluctuations of diet composition.
- Describe daily and seasonal movement patterns of the Azores Woodpigeon by tracking individuals using GPS-VHF tags to better understand the habitat use of the species.
- Assess the current role of the Azores Woodpigeon as seed disperser for native and exotic-invasive plants and its impact on cultivated fields.
Results & Impact
Results are preliminary and consist of the molecular analysis of a first set of faecal samples (366 samples collected on Pico between May 2021 and January 2022, three seasons: summer, autumn and winter). Overall, 188 samples were confirmed to be from the Azores Woodpigeon (51.4%), 133 samples were inconclusive (36.3%) and 45 samples were assigned to the Azores Blackbird Turdus merula azorensis (12.3%). A total of 111 operational taxonomic units (OTUs) were retained after bioinformatic analysis: 1 OTU assigned to family level, 36 OTUs to genius level and 74 OTUs to species level.
The most frequent OTUs were Rumex sanguineus (percentage of occurrence: 11.7%), Trifolium repens (9.7%), Rumex conglomeratus (7.6%), Rumex sp1. (7.2%) and Crepis sp1. (5.2%). Native Ilex perabo (1.3%) and Morella faya (1.3%) also had relatively high percentages of occurrence.
Diet data were analysed considering two parameters: richness (number of different OTUs) and composition (identity of OTUs).
Preliminary results show that total richness (or niche-width) differed between seasons, with diversity being lower in winter than in autumn and summer.
Average richness per sample also differed between seasons, with higher diversity in summer, followed by winter and lower diversity in autumn. We found that land cover had a significant effect on average richness in summer and autumn. In summer, agricultural area had a negative effect on average richness, while urban land area had a positive effect on the average richness. In autumn, average richness was positively related to the area of native forest.
Analyses also suggest that season and land cover had significant effects on diet composition. In summer, the exotic weed Crepis sp. was less consumed in locations with a higher proportion of urban area. In autumn, the native tree Ilex perado and exotic weed Poa sp. were more consumed in locations with a higher proportion of native forest. Finally in winter, the native tree Myrsine africana was more consumed at locations with a higher proportion of native forest and the exotic weed Ranunculus repens was more consumed at locations with a higher proportion of agricultural area.