Abstract
Few studies have related bird species richness and abundance with vegetation structure at different successional stages in pine-oak forests of Mexico. We studied changes in the bird community across three successional stages of pine-oak forest: early, intermediate, and mature. Also, we related bird community attributes—including generalist and specialist birds—with vegetation variables. We analyzed the vegetation and estimated bird abundances in 10-min-count periods in 10 circular plots per successional stage. We recorded a total of 71 bird species: 21 were specialists and 50 were generalists. The completeness of species richness was between 79 and 88% in the sampled habitats. Diversity profiles were consistently larger in the intermediate stage, except for its species richness that was not different between this and the early stage. We found a more richness and a higher number of individuals of generalist in the early and intermediate stages. The abundance of specialists was higher in the mature forest. An ordination analysis showed that generalists were associated to different variables. This suggests that these species can adapt to different forest conditions. Some specialist birds were more abundant in sites with high dominance of trees. Our results confirm the importance of maintaining not only mature forests but also young successional stages in order to conserve the species typical of secondary pine-oak forest bird species.
Highlights
Bird species richness and abundance vary across forest successional stages [10]
Tree richness and abundance were significantly highest in mature forest in comparison to the early and the intermediate stages (Table 1), while shrub richness and abundance did not show significant differences between the three successional stages (Table 1)
The structural variables were significantly highest in the mature forest in comparison to the other two stages, except for plant density, which was greater in the intermediate stage, this difference was not significant (Table 1)
Summary
The composition and the structure of vegetation influence the abundance and the distribution of birds in different environments [1–4]. Many of these landscapes are currently characterized by secondary forest intermixed with scrublands, grasslands, and farmlands [7]. In these landscapes, vegetation in later successional stages is usually taller and has greater biomass, higher number of vertical structural components, and higher number of tree species [7, 8]. Vegetation in later successional stages is usually taller and has greater biomass, higher number of vertical structural components, and higher number of tree species [7, 8] Due to their complexity, these habitats often provide a variety of food and nesting sites for specialist birds, in particular [3, 9]. Connell [14] suggests that species richness is greater in sites in the intermediate phase of succession because species characteristic of both early and mature forests (i.e., generalists and specialists) can coexist
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