A new review has shone a light on the complexities of nest predation and its devastating effect on populations of temperate forest and woodland birds in Australia.

Murdoch University adjunct researcher Graham Fulton collated information on more than160 research papers on nest predation to gain an understanding of this multi-faceted issue, and to highlight the effectiveness of attempts to stop nest predation.

“Nest predation affects a critical stage in bird life histories, which has a direct impact on the numbers of birds growing to adulthood,” Fulton said.

“It is considered to be the greatest cause of nest failure and is therefore of paramount importance to bird conservation.

“There are conservation strategies developed to mitigate nest predation, but this is the first study to draw them together for comparison.”

Fulton said one of the popular theories for the general decline of birds worldwide is the role of medium sized predators, known as mesopredators.

“Removing the apex predators of the area, such as wild dogs and feral cats, causes the smaller predators such as currawongs and butcherbirds to swell in numbers. This is considered to have a significant impact on the survival chances of juvenile birds of smaller species, particularly in ground dwelling birds.

“One conservation strategy has been to selectively remove introduced mesopredators but removing one species will directly result in the rise in another mesopredator, so the benefit of that strategy may be negligible.”

Fulton also investigated the use of artificial nests, which have been used extensively to identify predators and test various hypotheses.

“Unfortunately results do not mirror those seen in natural studies, which undermines their usefulness,” he said.

A significant group of studies testing nest success based on the distance to the edge of the forest or woodland was also examined, with varied results.

“These studies need more complex analyses to explain these results, factoring in the fragment size, vegetation structure and animals present to explain whether there is real increase in nest predation towards the edges of a woodland,” he said.

“A large number and variety of nest predators have been reported but we still need more information on the identity and roles of nest predators. We also need to look for stronger patterns around the impact of nest characteristics amongst related species.”

Fulton said that despite a wealth of research study on this topic, there was still no clear thought on how to stop nest predation in these smaller birds.

“We need to look at more practical interventions such as culling nest predators and placing cages around threatened birds,” he said.

“This is a complex issue that will require conservation researchers from around Australia to work together to find some solutions before it is too late.”

The review was published in Pacific Conservation Biology and can be read here.