All boom and no bust for many Newhaven bird species

All boom and no bust for many Newhaven bird species
Field Program
Science: surveys and research
Budgerigar | Zebra Finch

Jan 2017: Australia’s deserts are renowned for their dramatic multi-year cycles of boom and bust – the working theory has been that wildlife populations fluctuate in response to abundant rainfall and decline at times when rainfall is low. However, research analysing data from six years of bird surveys at AWC’s Newhaven Wildlife Sanctuary suggests that even during ‘bust’ years, there’s still plenty of life in the system.

The study, published in the Journal of Arid Environments, aimed to tease apart the responses of birds at a species and community level, to see whether the ‘boom and bust’ patterns held true.

The research revealed that massive fluctuations in overall abundance could be attributed to just a few species, which moved into the area to make the most of favourable conditions following rain. For this group – which included nomads like Masked Woodswallows, Cockatiels and Budgerigars – abundance was closely tied to rainfall over the preceding 12-month period.

Newhaven Wildlife Sanctuary experienced high rainfall in 2016. Image: Joey Clarke/AWC

However, there was also a large and diverse group of species which maintained remarkably stable populations throughout wet and dry years. This group included rare species like the Dusky Grasswren and Rufous-crowned Emu-wren, as well as more widespread species like the Rufous Whistler, Singing Honeyeater and Crested Bellbird. These resident birds comprised 28 species – more than half of the 48 species included in the study.

Pied Honeyeater numbers at Newhaven fluctuate in response to rainfall, but the boom & bust pattern is less widespread among desert birds than previously thought. Image: Josef Schofield/AWC

The analysis indicated that ‘boom and bust’ is only part of the story; for a large and diverse group of birds, dry years don’t mean bust at all. Australia’s deserts don’t just spring to life after rain, they support a rich diversity of species which can thrive through cycles of wet and dry years.

This kind of analysis is made possible by AWC’s commitment to long-term ecological monitoring. Comprehensive bird surveys are carried out at Newhaven annually by AWC across 66 sites in both wet and dry years. The surveys, which have now been conducted for 9 years, can only happen thanks to a dedicated team of volunteers, some of whom travel thousands of kilometres to take part.

Zebra finches are highly responsive to rainfall, moving in quickly when favourable conditions arise. It’s a mystery how nomadic birds can assess conditions from a distance. Image: Andrew Morton/AWC

Reference: Jordan R, James AI, Moore D, Franklin DC (2017) Boom and bust (or not?) among birds in an Australian semi-desert. Journal of Arid Environments 139: 58–66