Partial topographic map of Brookfield Conservation Park.

Season in review

After four months in the Australian bush, I've come back to Nebraska. It's been a bit of a shock exchanging the austral summer, with its temperatures of 40°C and above (that's upwards of 100°F), for the 40°F and below (~4°C) of a Midwestern winter. Although it's great to be back with family and friends for the holidays, I found it difficult to leave Brookfield, the birds, and good friends in Australia this year.

And what a year it has been! With the help of three amazing field assistants, my co-investigators and I were able to collect over 900 blood samples from 30 species. We had especially good coverage for a few key species for which we'll be able to pair infection data with information about individual-level social behavior. These color-banded species are indicated by an asterisk (*) in the table below.

Figuring out how to efficiently capture and sample such a diverse array of species proved an exciting challenge. Each species has a unique suite of behavioral characteristics influencing the habitat strata that they occupy, how they use space within their territory, how frequently and how far they move, and how tolerant they are of clumsy humans moving about in their vicinity.

During past work studying fairywrens at the field site, we've developed a pretty successful capture strategy. Though furtive and often tough to follow, fairywrens tend to stay low in the understory and often don't move more than 100 meters or so at a time. Consequently, they're relatively easy to flush into nets for capture. In contrast, many of the thornbills and honeyeaters that I hoped to sample for my study make regular use of high canopy layers and readily make long flights above the mallee in search of forage. As we soon found out, trying to capture many of the other species that inhabit the park using the same tactics that we'd previously used for fairywrens was a recipe for frustration.

 

Map of Brookfield Conservation Park (highlighted in green) showing some of the more than 300 net sites at which we successfully sampled birds this season. The number of species sampled at a site is indicated by the color of the marker.

So we adapted our approach, and found other ways to meet our sample goals. In the process, I found ample opportunity to consider the range of species' responses to different capture approaches, and how that range of behaviors might reflect different exposure risks or transmission pathways.

In addition to troubleshooting capture strategies, the field season had a few other surprises in store for us this year. While it was a comparatively mild season in terms of temperature, with only four of the 111 days we spent in the park topping 40°C, dry and windy conditions made for some days of unusual weather. The Murray Mallee region has been experiencing drought conditions over the past several years, and high winds gave us some eerie views of raised dust (and not much else).

 

On a clear day, Accommodation Hill is visible 17 miles (27 km) to the west from Brookfield across the Murray basin. Loose soil, drought conditions, and high winds resulted in several days of raised dust this season, reducing visibility and making fieldwork difficult.

When it's very hot, we stop netting for the birds' safety. On days with high winds, bird behavior and activity levels change in ways that drastically reduce capture success, making those days more productively spent on other pursuits such as surveying to re-sight color-banded birds, entering data, or organizing samples.

I'm excited to begin analyzing samples next month, and look forward to sharing the results with you. As always, thanks for your interest and support.

—Ian