Why are whales so big?

Anyone who has witnessed majestic whales or lumbering elephant seals in person would be forgiven for associating ocean life with unlimited size in mammals, but new research reveals that mammal growth is actually more constrained in water than on land, according to Science Daily.

This finding researcher is in contrast to previous theories suggesting that pressure on body size should be more relaxed in water, perhaps because of the large environment and ability for animals to float rather than have to support their body weight on legs.

Instead, the group found that aquatic mammal size is bounded at the small end by the need to retain heat and at the large end by difficulties getting enough food to survive.

"Many people have viewed going into the water as more freeing for mammals, but what we're seeing is that it's actually more constraining," said co-author Jonathan Payne. "It's not that water allows you to be a big mammal, it's that you have to be a big mammal in water -- you don't have any other options."

Getting big, but not too big

Although mammals that live in water share a similarly oblong body shape, they are not closely related. Rather, seals and sea lions are closely related to dogs, manatees share ancestry with elephants, and whales and dolphins are related to hippos and other hoofed mammals.

Physical disability boosts parenting effort, beetles study shows

Animals that carry a physical impediment can work harder to rear their young as a result, a study of insects has shown, according to Science Daily.

In a study of beetles, those that were given a physical disadvantage -- tiny weights attached to their bodies -- spent more time feeding their young compared with others, research showed.

They may behave this way, sacrificing valuable resources to care for their offspring, in case they are not able to reproduce again, scientists suggest.

Researchers studied burying beetles -- which are known for their intensive parenting, with both males and females are involved in rearing their young.

New Genetic Research shows extent of cross-breeding between wild wolves and domestic dogs

Mating between domesticated dogs and wild wolves over hundreds of years has left a genetic mark on the wolf gene pool, new research has shown, according to Science Daily.

The study showed that around 60 per cent of grey wolf genomes carried small blocks of the DNA of domestic dogs, suggesting that wolves cross-bred with dogs in past generations.

The results suggest that wolf-dog hybridisation has been geographically widespread in Europe and Asia and has been occurring for centuries.

Altering songbird brain provides insight into human behavior

Songbirds are providing insight into how a specific set of neurons may guide the learning of vocal behaviors in humans, according to Science Daily.

A study demonstrates that a bird's song can be altered -- to the syllable -- by activating and deactivating a neuronal pathway responsible for helping the brain determine whether a vocalization is performed correctly. Previous research has shown that when a song is performed without perceived error, certain neurons release dopamine to brain areas involved in motor control. The new study shows that by activating and suppressing these neurons, scientists can prompt the birds to change specific syllables in future performances.

Feed the birds, but be aware of risks

Scientists are warning of the risks of wild birds spreading diseases when they gather at feeders in gardens.

Experts led by Zoological Society of London say people should continue to feed birds, especially in winter, but should be aware of the risks, according to BBC.

If birds look sick, food should be withdrawn temporarily, they say.

The review of 25 years' worth of data identified emerging threats to garden birds. Finches, doves and pigeons are vulnerable to a parasite infection.