How does fear shape the behavior and conservation of deer, moose and antelope, not to mention carnivores such as wolves, bears, and even tigers? What is the natural state of wildlife, and how do animals know or learn which species to ignore or fear? Should we reintroduce predators to former habitats, even though the prey animals may be unprepared for their return?

Clutch size varies greatly between bird species. Researchers now have a better idea why. Analyzing data on clutch size, biology, and habitat for 5,290 species of birds, a team of biologists — Walter Jetz (UC San Diego), Cagan H. Sekercioglu (Stanford University), and Katrin Böhning-Gaese (Johannes Gutenberg-Universität) — developed a model to predict variations in the number of eggs a species lays. They found clutch sizes are consistently largest in cavity nesters and in species occupying seasonal environments. The findings add depth and complexity to previous research that has shown short-lived species — ones that face high predation or have low survival rates among offspring — tend to lay more eggs than longer-lived species, which invest more resources in raising their offspring.

A recent study in Current Biology finds that paper wasps are capable of remembering rivals a week after initially meeting. As a highly social insect, the discovery proves that the paper wasps' social interactions are based on applied memory rather than simple instinct. The finding overturns many ideas about the intelligence of insects.

Researchers have discovered a previously unknown migratory route for the northern bluefin tuna, proving for the first time that the species' Mediterranean and North American subpopulations interact. According to the paper published in Science the two groups meet as juveniles then return to their birthplace to spawn. For a critically-endangered species that is still heavily fished, the new finding has large conservation and management implications.

Researchers have discovered a dung beetle that may be evolving into separate species in a few decades rather than thousands or millions of years. Separated geographically, sub-populations of the species show large differences in the size of their genitalia and horns. Such distinctions could create new species in a short time, because beetles with largely different genitalia cannot successfully mate.

The popular image of hunting wolves is a pack bearing down on a deer, working in concert to make the kill. However, new research has discovered that when available, wolves largely forgo hoofed mammals for salmon.