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Older Male Sparrows Not Threatened by Younger Males

Wed, 15 Feb 2012 14:57:05 +0000

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

Tiny Tarsier Produces Ultrasonic Calls

Mon, 13 Feb 2012 16:27:13 +0000

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.

Rare Bird Rediscovered in China

Tue, 07 Feb 2012 15:14:06 +0000

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.

Arachnid Pictures

Fri, 27 Jan 2012 12:51:54 +0000

Arachnids are more than just spiders. Browse our new Arachnid Pictures to get a close-up glimpse of arachnid diversity.

Sea Turtles Coping with Climate Change

Wed, 25 Jan 2012 22:33:59 +0000

The gender of a baby green sea turtle is determined by the temperature the egg experiences during incubation. When temperatures are warmer, more females are born while. Conversely, when temperatures are cooler, more are males born.

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Crustaceans - Mobile Swiss Army Knives

Wed, 25 Jan 2012 16:11:41 +0000

Crustaceans are one of four basic groups of arthropods (the other three being the myripods, arachnids and insects). The group includes crabs, lobsters, shrimp, krill, crayfishes, wood lice and barnacles.

Crustaceans are by no means as diverse in species number as the insects or even the arachnids, but they do come in a mind-boggling array of shapes and sizes. Since crustaceans are with few exceptions aquatic species, they have escaped the demands of life on land (demands which place limitations on the ornateness of body form that can develop).

Crustaceans are an old group of animals, dating back some 500 million years to the Cambrian. Their body plan is simple yet elegant and adaptable. In his book, The Variety of Life, Colin Tudge likens crustaceans to mobile Swiss Army knives—composed of up to 32 segments each equipped with its own pair of appendages that are modified for a variety of tasks: locomotion, defense, communication, feeding, hunting, reproduction. Each segment and its appendage is like a separate tool and together the segments and appendages form as well-adapted a tool kit as a Swiss Army knife.

Photo © Ben Cranke / Getty Images.

Arachnids - Not Simply Spiders

Wed, 25 Jan 2012 13:29:32 +0000

Although scientists don't know exactly how many species of arachnids there are alive today, their best guess puts the species count in the ballpark of 100,000 of which, more than 40,000 are spiders. Since that means nearly half of all archnids are spiders, it's easy to forget the other lesser-known eight-legged creatures that belong to the group.

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Rare Langur Discovered in Borneo

Sat, 21 Jan 2012 20:43:21 +0000

Scientists have discovered a previously unknown population of Miller's grizzled langurs (Presbytis hosei canicrus), an endangered primate thought to be on the verge of extinction. The rare langurs were discovered in the Wehea Forest of East Kalimantan, Borneo. Wehea Forest is a 38,000 hectare patch of undisturbed rainforest that is home to nine species of primates including gibbons and the Bornean orangutan.

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Thailand's Anti-Poaching Efforts Paying Off

Tue, 17 Jan 2012 16:02:28 +0000

Anti-poaching efforts are successfully helping to protect many rare species in Thailand, according to a recent report by the Wildlife Conservation Society (WCS). Videos and images collected from WCS camera traps provide park rangers much needed data that can be used to arrest and convict poachers. Additionally, camera trap information is used by Wildlife Conservation Society scientists to measure and track population sizes of numerous local species.

The camera traps, placed in multiple locations within Thailand's Western Forest Complex, have capture footage and pictures of a variety of species including wild pigs, leopards, tigers, gaurs, Asian elephants, sun bears, clouded leopards, banteng and many others. Camera trap data indicates that there are between 125 and 175 tigers living within the 18,000-square kilometer Western Forest Complex.

Thailand serves as a critical front in the battle against poachers. The WCS has joined forces with the Thai government to train park rangers how to protect the region's rare animals from illegal hunting. Many park rangers and wildlife guards from other Asian countries are trained in Thailand, so they can learn how to best protect the rare wildlife from poaching in their own countries.

Photo © DNP-Government of Thailand / WCS Thailand Program. Camera trap image of an Asian elephant calf in a heard of adults, photographed in the Western Forest Compex, Thailand.

New Viper Discovered in Tanzania

Tue, 17 Jan 2012 12:19:51 +0000

Scientists working in the remote montane forests of southern Tanzania have recently discovered a new species of viper. The new snake, named after the daughter of one of the scientists involved in the discovery, is called the Matilda's horned viper (Atheris matildae).

The discovery was made by a team of experts that included Michele Menegon of Museo delle Scienze of Trento, Italy, Tim Davenport of the Wildlife Conservation Society and Kim Howell of the University of Dar es Salaam.

Matilda's horned viper is similar to (and larger than) the Usambara bush viper (Atheris ceratophora). Genetic analysis has revealed that the two species diverged about 2.2 million years ago.

Scientists expect the Matilda's horned viper to be classified as critically endangered by the IUCN due to the species' restricted range. It is thought that the Matilda's horned viper survives within a fragment of montane forest no larger than 100 square kilometers.

Since illegal wildlife trade presents a serious threat to many reptiles in the region, the exact location of the new snake's habitat has not been publicized.