Older male white-crowned sparrows don't see younger male sparrows as much of a threat. When vying for mates or squabbling over territory, older males don't often bother challenging their younger rivals because they pose little credible competition. Instead, they only pick a fight with other older males that could pose a significant threat to their superiority.

It turns out, the way these birds figure out each others' seniority is based on their songs as well as their plumage. Male white-crowned sparrows use song for multiple purposes including attracting a mate and claiming their territory. Since young male white-crowned sparrows sing differently than older males, song can be used to distinguish age.

After mapping the territories of 16 male white-crowned sparrows, the research team was able to observe how males of different ages responded to songs made by intruders.

They found that older birds did nto react as strongly when they heard the song of a younger bird in their territory.

Photo © Douglas Nelson / Ohio State University

Scientists have discovered that tarsiers, a group of tiny primates native to Southesast Asia, produce ultrasonic calls that are well beyond the audible range of humans. The frequency of the tarsirs' calls is among the most extreme of all animals, and is comparable to the ultrasonic calls made by dolphins and bats. The team of scientists, led by Nathaniel Dominy of Dartmouth, focused their study on a species of tarsier native to the Phillipines.

Tarsiers are a group of primates that diverged from monkeys and apes some 60 million years ago. The group has changed little during the past 45 million years and are considered to be living fossils. They measure a mere 5 inches from head to tail and live on a diet of small animals such as insects and reptiles.

Dominy and colleages noticed that the that tarsiers of Borneo and the Philippines were quieter than species elsewhere. This observation led them to inquire whether the vocalizations of the Borneo and Philippine tarsiers were outside the range of human hearing. They recorded sounds of 35 wild tarsiers on special equipment that captures sounds well outside the range of human hearing. They discovered that the tarsiers were producing ultrasonic calls that were otherwise similar to calls produced by tarsier species that call in the audible range. Further tests showed that tarsiers could indeed hear the ultrasonic calls.

Their findings reveal that tarsiers can both send and receive vocal signals in the ultrasonic range.

Photo © Nathaniel Dominy / Dartmouth.

In the late 1800s and early 1900s, a reclusive species of bird was discovered in China. The bird, given the common name of "blackthroat", was rarely sighted for over a century after its initial discovery. Now scientists working in the Quinling Mountains in Shaanxi Province in north central China have announced the rediscovery of a breeding site of blackthroats nestled in the dense bamboo, coniferous and broadleaf forests that blanket the mountain slopes above 2400 meters.

The research team, which included scientists from China and Sweden, discovered seven males in Foping National Nature Reserve. An additional seven males were located in Changquing National Nature Reserve.

Blackthroats (Luscinia obscura) bear some resemblence (size and shape) to European robins. But instead of a rusty red breast, blackthroats have a jet blakc throat and breast. Females are thought to have a brown throat and breast, but so far only males of the species have been definitely identified.

The species is classified as vulnerable according to the IUCN Red List due to its small and presumably declining population. It faces threats from habitat destruction as a result of widespread logging and agricultural land use throughout its range.

Photo © Per Alström / Foping National Nature Reserve, Shaanxi, China.