In many birds, individuals 'answer' the songs of their pair-mates to produce vocal 'duets'. One hypothesized function of song answering is that it prevents extra-pair birds from intruding into the duetting pair's territory to obtain copulations or usurp one of the pair-mates. In this capacity, answering may signal that the pair-mates are close together, and so are prepared to defend against suc...

The contribution of indirect fitness to inclusive fitness is expected to increase as the reproductive skew increases, with indirect fitness being the only component of inclusive fitness of sterile individuals in eusocial species. However, the relative contribution of indirect fitness to inclusive fitness has rarely been evaluated empirically. Using data from a long-term study (1962–2003), we sh...

Changes in mating signals among populations contribute to species formation. Often these signals involve a suite of display traits of different sensory modalities ("multimodal signals"); however, few studies have tested the consequences of multimodal signal divergence with most focusing on only a single divergent signal or suite of signals of the same sensory modality. Populations of the chestn...

Extensive forest conversion of the low-valued natural hardwood forest into coniferous plantations is the possible cause of the critical problem of squirrel debarking. The tree squirrel that causes the major damage is the red-bellied tree squirrel (Callosciurus erythraeus). Conifers are more susceptible to the damage than are hardwood species, especially the exotics. Intermediate-aged plantation...

Wildlife are increasingly recognized as important biological reservoirs of zoonotic species of Cryptosporidium that might contaminate water and cause human exposure to this protozoal parasite. The habitat range of the yellow-bellied marmot (Marmota flaviventris) overlaps extensively with the watershed boundaries of municipal water supplies for California communities along the foothills of the S...

Mammalian sociality varies both within and between species. We developed a trait-based method to quantify sociality in a continuous way to study the adaptive utility and evolution of male social behavior. The metric is based on 3 key traits—mutual tolerance, collaboration, and partner preference; males with no traits are not social, whereas those with all 3 traits are described as forming coali...

Correspondence and present address: D. T. Blumstein, Schools of Behavioural and Biological Sciences, Macquarie University, Sydney, NSW 2109, Australia (email: [email protected]). K. B. Armitage is at the Department of Systematics and Ecology, University of Kansas, Lawrence, KS 66045, U.S.A. When we see animals do things that are potentially risky, such as alarm calling around predator...

The fire-bellied toads Bombina bombina and B. variegata differ extensively in biochemistry, morphology, and behavior. We use a survey of five diagnostic enzyme loci across the hybrid zone near Cracow in Southern Poland to estimate the dispersal rate, selection pressures, and numbers of loci which maintain this zone. The enzyme clines coincide closely with each other and with morphological and m...