A team of conservationists recently captured a female Amur leopard (Panthera pardus orientalis) from the rugged Primorsky Krai region of Russia's Far East. The scientists gathered detailed health information for the leopard, including blood analysis, electrocardiogram, and weight measurements. After the medical data was collected, they released the leopard unharmed, back into its home territory. The team is now in the process of evaluating the data they collected to determine the cat's overall health and look for any signs of inbreeding.

The Amur leopard is among the world's most endangered large cats—only 25–40 individuals remain in the wild. In 2006 and 2007, health analysis of three Amur leopards revealed that all had significant heart murmurs—a condition that reflects a possible underlying genetic disorder within the small population. If inbreeding is determined to be a problem for the Amur leopard population, conservationists might consider trans-locating leopards from other regions to increase the genetic diversity of this rare subspecies.

The conservation team included a collaboration of experts from the Wildlife Conservation Society, the Russian Academy of Sciences Institute of Biology and Soils, Wildlife Vets International, the National Cancer Institute, and the Zoological Society of London. They are hopeful about the future of the rare cat:

"We are excited by the capture, and are hopeful that ongoing analysis of biomedical information will confirm that this individual is in good health. This research is critical for conservation of the Far Eastern leopard, as it will help us to determine the risks posed by inbreeding and what we can do to mitigate them." ~ Alexey Kostyria, Ph.D., senior scientist at IBS and manager for the WCS-IBS project.

Like many large carnivores around the world, the Amur leopard faces multiple threats, the most onerous of which are poaching and habitat loss. Fortunately, the population of Amur leopards, though small, has remained steady for the last three decades. But the population exhibits a high rate of turnover of individuals and experts hope that if inbreeding is fueling this turnover, then any action to reduce its effects would greatly benefit the subspecies.

Find out more:

• Saving Russia's Rare Panthers
• World's Rarest Big Cat Gets a Check-Up (Eurekalert)

If you're interested in vertebrate paleontology in general (and the evolution of the first tetrpods in particular) then you might want to take an hour out of your day and watch this lecture by Neil Shubin. In it, Dr. Shubin describes his research in the Canadian Arctic and the 2004 discovery of Tiktaalik roseae, a 375-million-year-old fossil that fits into an interesting gap in the fossil record between fish and terrestrial tetrapods.

Scientists from Boston University have discovered that the embryos of red-eyed tree frogs (Agalychnis callidryas) use up most of the oxygen within their eggs before they hatch. Undergraduate Jessica Rogge and associate professor Karen Warkentin found that tree frogs—whose eggs are ready to hatch about four days after they have been laid—delay hatching for several additional days. During that time, the tree frog embryos continue to grow and consume oxygen, all the time increasing their risk of asphyxiation.

By delaying hatching, the frogs balance the odds of survival in their favor: the larger the frog embryos grow before hatching, the better their chances of survival after hatching.

The red-eyed tree frog inhabits the tropical rainforests of Central America. Female red-eyed treefrogs lay their eggs on leaves that overhang ponds. When the eggs hatch, the tadpoles fall into the water below. Once in the water, the tiny tadpoles are vulnerable to predation by fish, and larger tadpoles are better able to fend for themselves than smaller tadpoles.

Rogge and Warkentin found that the frog embryos orient themselves so that their gills are positioned in the area of the egg with the richest supply of oxygen, such as near the surface of the egg that is exposed to the air. This ensures that the embryos can take advantage of every scrap of oxygen the egg has to offer before hatching.

That embryos are capable of doing this is quite remarkable—the developing frogs have no gills, blood, or capacity for muscle movement. Yet they somehow they are able to maintain their head in the position of optimal oxygen supply within the egg.

Rogge and Warkentin adjusted the position of the embryos within the eggs to see what would happen if the embryos were reoriented away from the oxygen 'sweet spot'. The researchers gently probed the embryos, nudging them into different positions and moving the head away from the oxygen-rich part of the cell. They found that the embryo soon drifted back to its original position, with its head oriented towards the area of richest oxygen concentration.

Find out more: Red-eyed Tree Frog Embryos Actively Avoid Asphyxiation Inside Their Eggs (Eurekalert)

Top: Photo © Alvaro Pantoja / Shutterstock.
Bottom: Photo © Karen Warkentin / Boston University and STRI.

Eland antelopes (Tragelaphus oryx) are the largest antelopes in the world but their considerable size doesn't mean they're eager to throw their weight around. It turns out, eland antelopes have developed elaborate means to avoid fights and in doing so, they avoid costly injury associated with physical conflict.

When settling disputes, male elands send out a set of signals that accurately reflect their size, age, and aggressiveness to other males—these signals serve to advertise the fighting ability of each male. If it is clear one individual would likely overpower an opponent, the weaker individual simply acquiesces, sparing both individuals any injury.

This complex communication process between rivals—referred to as agonistic signaling—is the focus of research reported earlier this month in the journal BMC Biology. The study's authors include Jakob Bro-Jørgensen from the Zoological Society of London and Torben Dabelsteen from the University of Copenhagen.

Bro-Jørgensen and Dabelsteen recorded data for eland antelopes in Kenya's Masai Mara National Reserve and the Olare Orok Convservancy. The study area stretched over 400 square kilometers of acacia savannas and open grasslands.

Elands roam their grassland and acacia savanna habitat in loose groups. The size of these groups can vary. Many groups consist of less than 20 individuals while groups that consist of several hundred individuals can also form. Male elands are organized into a distinct hierarchy.

Based on their observations, Bro-Jørgensen and Dabelsteen identified three agonistic signals that rival male elands use to communicate dominance to each other:

• delap size
• knee clicks
• hair darkness

Each signal conveys a different type of information. Dewlap size provides a measure of the animal's age—older males have larger dewlaps than younger individuals. Since older elands are likely to have more fighting experience, a larger dewlap gives some indication of which individual is more likely to prevail in a fight.

Knee clicks provide a measure of the animal's size. Knee clicks are thought to be produced by a tendon slipping over the knee joint (much like sound made when plucking a taught string). Knee clicks are loud enough to be heard several hundred meters away. In larger antelopes, the sound produced is lower frequency than in smaller antelopes, so the deeper the sound, the larger the animal.

Finally, hair darkness provides a measure of relative aggressiveness. Darker hair, which results from higher levels of androgens, indicates a more aggressive individual.

View photographs from the study →

Find out more: Bro-Jørgensen J. and T. Dabelsteen. 2008. Knee-clicks and Visual Traits Indicate Fighting Ability in Eland Antelopes. BMC Biology. November 5, 2008.

Photo © Jakob Bro-Jørgensen / Cambridge University.