Pollen analysis as an ecological proxy for the assessment of habitat use of the endangered Black-polled Yellowthroat (Geothlypis speciosa) and sympatric Common Yellowthroat (G. trichas)

Abstract

We present a novel application of palynological analyses to assess habitat use of the endangered Black-polled Yellowthroat (Geothlypis speciosa) and the sympatric Common Yellowthroat (G. trichas) in Lake Cuitzeo, Mexico. Since field monitoring of songbirds can be difficult due to complex habitat requirements, behavioral, or logistical issues, our results provide an important methodological alternative for habitat assessment and conservation monitoring of species difficult to study with traditional methods. We found significant differences between pollen rain in water samples and pollen loads in feathers. Pollen loads were comparable between bird species during both rainy and dry seasons. Contrary to previous assumptions, Black-polled Yellowthroats showed pollen loads associated with terrestrial habitats, particularly during the dry season. Our results on equitability resource-use, showed marked differences between seasons, being more homogeneous in the dry season than in the rainy season. In addition, equitability values of pollen loads were similar between sexes in Common Yellowthroat but significantly higher in males as compared to females' Black-polled Yellowthroats, suggesting some degree of resource partitioning. GLM's identified a significantly negative relationship between anemophilous and entomophilous pollination syndromes in both species and the pollen rain recorded during dry and rainy seasons, as well as a significant effect of season sampling on pollen load, but no effect of species, sex, or any interaction with season upon pollen loads. We concluded that pollen analysis was a useful tool for the study of use of habitat in birds.

Keywords

• conservation planning
• cuitzeo
• feathers
• palynology
• pollen rain
• vegetation
• wetlands