The Powerful Owl Project

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The Powerful Owl Project in 2012 has taken on an expanded form from the pilot program in 2011 with the appointment of Dr David Bain as the Powerful Owl Project Officer. Funding has been secured from the NSW Environmental Trust and the BASNA Twitchathon to run the project until March 2014.

From the fantastic support received from volunteer Owl Observers in 2011 and 2012 and the work of Birds In Backyards, the project is gaining significnt momentum and generating some great results. Regular project updates will be provided on the website. The current results from the program follow.

Powerful Owls in our Urban Centres

The Powerful Owl is found throughout the outer suburbs of the greater Sydney metropolitan area and many urban areas north of Sydney, in Melbourne and Brisbane, particularly where these suburbs adjoin substantial areas of bushland and reserves. Over the past 10 years or so in Sydney, there have been a number of sightings much closer to the city, even in the Royal Botanic Gardens.  Powerful Owls nest inside large hollows of big old trees and they usually roost during the day among the dense leafy foliage of tall understorey trees and shrubs.  Powerful Owls feed almost exclusively on large tree-dwelling mammals, especially the Common Ringtail Possum, but they also take a few large birds.  The Grey-headed Flying Fox is a favourite food item for the owls, especially when there is a Flying Fox colony nearby.

The Powerful Owl is a good "flagship" species to help us learn more about the conservation requirements of this species and those of other owls, as well as the needs of many other forest-dwelling species.  Because Powerful Owls are difficult to find and occur at low population densities, we do not know how many of them there are in the Sydney region.  As a first step towards effective conservation of the Powerful Owl, we need to be aware of the habitat used by this owl and whether its numbers are increasing or decreasing.

Aims

We want to locate all the breeding pairs of Powerful Owls in the Sydney, Central Coast and Newcastle regions, identify where their nest locations are and record the outcome of each nesting attempt at the end of the breeding season. This information will identify the critical roosting and breeding requirements of the owls and the locations of important areas requiring protection. We are also collecting pellets and habitat information to understand their urban ecology more, as well as looking at incidents to look at threats in the urban area.

In addition, the project will also focus on the development of education materials with partners such as Taronga Zoo and engage various land managers to workshop management measures to help in the conservation of Powerful Owls and their habitat.

Results

The pilot program run in 2011 attracted over 50 dedicated volunteers owl observers and over 250 sightings from the general public. Owls were found in 15 territories that bred and fledged at least one, but usually two, chicks. Owls in a further 13 territories or seen as pairs were recorded, but the outcome of these breeding events was unknown or nest locations not identified.

In the 2012 breeding season there were 69 volunteer Owl Observers monitoring 83 sites across Sydney and Newcastle. Over 300 sightings from the general public helped to identify active areas across the study area and fine tune the breeding monitoring. By the end of the breeding season 47 territories were identified. Of these, 22 territories successfully raised and fledged 30 chicks with the remaining 25 territories either unsuccessful (4) or the outcomes were unknown but evidence suggested breeding was not attempted or the attempt was unsuccessful (21). These numbers are certainly much larger than the previous estimates made by Kavanagh (2004) of 20-30 pairs in the Sydney basin.

Unfortunately there were also 10 fatal car-strike incidents between March and September 2012.  Data from the previous five years from WIRES and Taronga Zoo suggests that this is not uncommon. There have been 115 recorded incidents from 2006 to 2012, with at least 65 of them fatal (some fates unknown) and over 50 of those incidents due to car-strike (some causes unknown). The project is in the initial stages of analysing the impact these incidents have on breeding success and whether any road kill hotspots can be identified to focus mitigation measures.

We are also commencing an analysis of landscape characteristics to identify any relationships or interactions that are good predictors of successful breeding territories. The project is also revisiting some work done on diet over 10 years ago to investigate any changes. Initial trends are showing a more varied diet in relation to mammal prey, but similar percentages of birds and insects.

Owl Observers (and members of the public) also made records of Powerful Owls with prey items and undertaking unusual behaviour. Ringtail possums were the favourite prey item but other birds and flying foxes were also sometimes observed. Interestingly one breeding pair were observed at the end of one breeding season with their own owlets and with the two owlets from a neighbouring territory also close by (whilst their parents remained in their own territory). Just how and why the neighbouring owlets ventured into another territory is unknown, but it is something we haven't seen before. Another interesting incident involved a hazard reduction burn where the mother and a juvenile owlet stayed in the area during the low intensity burn and seemed unfazed. However, the family subsequently left the area, presumably due to a reduction in prey availability. Continued surveys will help us to understand the outcomes at this site.

In summary, we now know that there is a significnt population of Powerful Owls within Sydney. Many of the “forested” territories include substantial areas of urban encroachment where the owls are subject to numerous human-induced threats.  We hope that as this project develops, we will begin to understand this population within the urban matrix and develop further understanding to help in the conservation of this species more widely.

To learn more about the project, learn how to find owls and how to submit sightings and surveys please go to our Powerful Owl Survey Page.

Please click to view a copy of the volunteer newsletter

To see video of the owls at the nest, please go to the Powerful Owl NestCAM

 

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