Powerful Owl: Sydney Update

Good day to you all and seasons greetings!

As we come to the end of the 2019 breeding season for Powerful Owls there is much to reflect upon. Firstly the stellar effort to build our owly empire from the sweat of our super citizen scientists, has yielded some really telling results. The season overall has been a hard one for a POwlys, with dry conditions ramping up aggression between owls and day birds. As a result of this and the impact of drought on prey populations, overall feldgeing success has declined markedly since 2018. Whilst the number of known territories in the Greater Sydney Basin increased from 206 to 214 between 2018 and 2019, the number of chicks fledged declined from 129 to only 81 tallied so far this season. Similar numbers of owls tried to breed but failed, and single chick clutches rose from 37 to 42% of the known breeding population. Fledgling survivorship is similar to levels seen on 2017, with about 13% fledglings dying within two weeks of fledge. Downturns in population growth are a normal, but the loss of adult birds coupled with poor breeding success is cause for concern.

The pressures of living in urban environments are well known for birds and cars have a large impact on Powerful Owls in the city.  PO Project estimates in 2014 suggested car strike may be responsible for the loss of more than 10% of the total Sydney Basin population. Car strike is a hard impact to quantify, simply because the records we collect are only a fraction of the true number of collisions occurring. Within the Project itself car strike accounted for over 80% of the deaths recorded in the last two years, with the majority of these strikes involving adult owls. Mining the compiled data base on mortality using data collected from 2014 onwards by the Project, wildlife rehabilitation groups and the Australian Museum we have identified 401 reports of owls in trouble, with 193 owls colliding with cars, glass and sometimes trees, buildings and trains. These records include 104 POwls, and other vulnerable owl species such as Sooty and Masked owls, and also Boobook and Barn owls. 

Enter stage left, Hilary Wilson, a student from UNSW researching the characteristics of road strike points for Powerful Owls. Hilary found tall trees associated with wider roads, situated further from creek lines to be consistent features of those areas we know are danger points for crossing Powerful Owls. Our future plans involve collaboration with the RMS to further investigate strike points and ways to mitigate against this.  Funding allowing, in conjunction with this work will be an assessment of rodenticides in road-killed owls, and we will aim to begin working on proactive corridor building using genetics, to help build habitat for our awesome urban owls.

The December newsletter for the Sydney Powerful Owl Project will be available from the project page by mid December at http://birdlife.org.au/projects/powerful-owl-project. Stay tuned.

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