Disproportionate emission of bubble streams with killer whale biphonic calls: perspectives on production and function.

Stereotyped pulsed calls were attributed to 11 killer whales (Orcinus orca) with and without synchronous bubble streams in three datasets collected from two facilities from 1993 to 2012. Calls with and without synchronous bubble streams and divergent overlapping high frequency components ("biphonic" vs "monophonic") were compared. Subjects produced bubbles significantly more often when calls had divergent high frequency components.

Differences in acoustic features of vocalizations produced by killer whales cross-socialized with bottlenose dolphins.

Limited previous evidence suggests that killer whales (Orcinus orca) are capable of vocal production learning. However, vocal contextual learning has not been studied, nor the factors promoting learning. Vocalizations were collected from three killer whales with a history of exposure to bottlenose dolphins (Tursiops truncatus) and compared with data from seven killer whales held with conspecifics and nine bottlenose dolphins.

Divergence of a stereotyped call in northern resident killer whales.

Northern resident killer whale pods (Orcinus orca) have distinctive stereotyped pulsed call repertoires that can be used to distinguish groups acoustically. Repertoires are generally stable, with the same call types comprising the repertoire of a given pod over a period of years to decades. Previous studies have shown that some discrete pulsed calls can be subdivided into variants or subtypes.

Environmental motivations for migration: population pressure, poverty, and deforestation in the Philippines.

"This paper uses a multinomial discrete choice model and data from the Philippines to examine migrant choice between alternative destinations. Travel costs and perceived opportunities at the upland frontier are more important than general (upland plus lowland) destination attributes that indicate more developed social infrastructure or greater expected welfare. For example, migration streams are larger to destinations where the public share of forestland and the road system are larger.