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Research has been conducted on the sexually selected traits in birds. The relationship between birds' songs and plumage elaboration in finches has been investigated and the results indicate that for the condition-dependent traits birds trade-off trait expression in response to changes in the information content of these traits.

Research has been conducted on the reproduction timing. The effect of this timing on the second brood incidence and parent survival in European coots has been investigated and the results indicate that adult survival does not depend on the season.

Mitochondrial sequence analysis in species of endemic Malagasy and other songbird species reveals that nine of the thirteen Malagasy birds form a clade. Data indicate that this endemic clade is followed by a group of Old World warblers and the clade rivals other island species in its ecological diversity.

Plumage evolution has been studied in orioles (Icterus) with repeated convergence and reversal in patterns found. It appears that sexually selected characters may evolve rapidly and show high levels of convergence and other types of homoplasy. Plumage characters were mapped onto a molecular phylogeny based on two mitochondrial genes. Overall convergence seen in the study is an interesting phenomenon of evolution. However, heavy reliance on plumage characters for constructing phylogenies should be avoided, based on findings of this research.

Little evidence was found for sympatric speciation in island birds based on a search for endemic congeneric species on isolated ocean islands. Of 46 islands and small archipelagos where at least one species of endemic land bird was found, seven paris of endemic congeners, excluding flightless rails, were found. Four pairs of the seven are potentially sister species. Three of the four have always been thought to come from double invasion from a mainland source. The remaining pair may have speciated allopatrically on a small archipelago.

Heritability of body size in two experimentally created environments, representing good and poor feeding conditions, respectively, was estimated utilizing cross-fostered collared flycatcher Ficedula albicolis nestlings. Young raised under poor feeding conditions attained smaller body size than their full-sibs raised under good feeding conditions. Parent-offspring regressions indicated lower heritability of body size under poor than under good feeding conditions.

Trilled vocalizations from 34 species of songbirds Passeriformes: Emberizidae were studied. Two acoustic variables, trill rate and frequency bandwidth, were measured for different trill types. Findings indicated that performance constraints have restricted the evolutionary diversification of trills. Specifically, the role of constraints linked with vocal tract modulations during song production and evolution was examined.

A study has been conducted to examine the phylogenetic relationships among populations of the yellow warbler, Dendroica petechia, from North, Central and South America and the West Indies using DNA restriction mapping. Results revealed 37 haplotypes, with the mtDNAs from North America distinct from those of the other populations, and a sequence divergence ranging from 0.14% to 3.17%. These suggest that multiple colonization may have taken place in faunal groups from the West Indies and the Caribbean Islands.