Save the Gouldian Fund Count 2019

Early September 2019 saw a happy band of volunteers assemble in the town of Wyndham in the east Kimberley region of WA to conduct the annual count of Gouldian finches in the Save the Gouldian Funds long term study site around Wyndham.

The Gouldian count was first done in 2008 and was completed every year to 2013. Unfortunately there was then a gap of four years before STGF recommenced the count in September 2018. This long-term monitoring of Gouldian finches using a well-defined protocol is critically important in understanding the population status of the Gouldian. As the Gouldian is a declared Endangered species we need to know how the population is trending. Is it increasing, static or decreasing?

The 2019 count followed a very poor 2018/19 wet season which saw the region receive only 60% of an average rainfall. Undoubtedly the biomass of annual sorghum, on which Gouldians depend for breeding from January through to about June, was very much reduced and by the time we got there in late August there was very little surface water remaining and many of the locations where we had counted in the past were totally dry. So our expectations were that numbers overall might be down.

The count depends on the fact that all finches need to drink regularly and all the population will come in for a drink early each morning before going off to forage. If we have counters at all the potential water points across the landscape early each morning we can get a reasonable snapshot of the local population.

Where did we count? 
Over the 10 years of STGF research around the Wyndham region, Sarah Pryke and her team identified all the “permanent” water points where Gouldians and other finches might find water late in the dry season. I previously showed the variation in water sources and this year many of our former count sites were totally dry as the previous wet season was very poor. Overall we had counters at 15 sites for this year’s count.

What did we find?
Over the five days we counted an average total of 200 adult Gouldians and 270 juveniles per day. So 57% of the birds were juveniles. The number of Gouldians counted this year was about 60% of the numbers we counted in 2018 when the daily average was 330 adults and 456 juveniles per day (58% juveniles).

Not surprisingly there was much variability among count sites as birds travel from feeding locations to watering points. The figure below shows this variation – some sites with consistent numbers, some with none, some with an occasional few. Some with a noticeably higher proportion of juvenile birds than others – for example compare Site 5 and Site 11.

Among the fully coloured Gouldians (juveniles were still in immature plumage) we recorded 81.9% Black-headed birds, 16.8% Red-headed and 1.3% Yellow Headed. These would have been the breeding population for the previous breeding season as none of the juvenile were yet coloured, though some had started to moult.

Sex ratio of birds across the head colours was highly variable. Black-headed birds were slightly female dominant – 46% male: 54% female. By contrast the Red-headed birds were strongly male biased – 81% male and only 19% female. All the Yellow-Headed birds were males. Clearly female Red-heads and Yellow-heads are being selected against.

A striking feature of the 2019 results was the variability in numbers counted across days and across sites. Through the week we saw a distinct increase in number of birds across all sites from a total of 200-300 birds on the first three days to 700-800 birds on the last two days.

Even more striking was the variability in numbers over time at some individual sites. For example at one site there were no Gouldians on two days and over 300 Gouldians on another.

We saw the same variability at a few other sites. This scale of day to day variation has not been seen in previous counts. Clearly the birds which appeared at this site on Day 4 had been finding water elsewhere on previous days and their fidelity to one water point was low. The results suggest that in extremely dry times where the birds are struggling to find food and water they will be utilising multiple water sources and travelling each morning to the site closest to where they have been feeding.

This spatial and temporal variability highlights why the count needs to be done over multiple days. One morning of casual counts could give a very misleading assessment of Gouldian populations! If we went to this site on Monday or Wednesday we would think there were no Gouldians, but on Thursday we would think there were plenty.

Numbers of other finches
Our count of Gouldians showed a significant reduction in numbers compared to 2018 and we might rationalise this as being due to the extremely dry season and lack of food resources to support breeding and survival. We also counted other finches and our data shows that the numbers of Longtails and Masks were both substantially increased compared to 2018 counts. So they appeared not to have suffered with the excessively dry conditions and it was noticeable that we saw several clutches of newly fledged Longtails, Masks and Zebras still being fed by their parents. These species were still breeding late into the dry season.

Overall this was another successful STGF Gouldian Count. The counts conducted from 2008 to 2013 showed Gouldians were slowly increasing in numbers in the Wyndham study area. Although we can’t conclude much from just two years of data since the count recommenced in 2018, it was clear that Gouldians were substantially less abundant this year. We will continue with the count for another 3 or 4 years and see where the population is trending.

STGF is immensely grateful to all the volunteers who helped with this year’s count. We couldn’t do this work without their involvement.