Powerful Owl Workshop Saturday the 14th of March 2020

Introduction.

Nocturnal birds are elusive, mysterious, and often less well understood than their day-active cousins.

They are essential regulators of food webs as predators of mammals, birds, frogs, and invertebrates.

Adaptations to nocturnal life such as exceptional eyesight, hearing, and a good sense of smell, give this special group of birds unparalleled hunting prowess.

As nocturnal birds are cryptic in both plumage and behavior, they can be difficult to detect. This guide will help you learn about and identify seventeen of our Australian nocturnal birds. This booklet includes information to identify owls, nightjars, owlet-nightjars, and frogmouths found on mainland Australia, Tasmania, and offshore islands but exclude vagrants.

We acknowledge that there are other nocturnal birds within Australia (e.g., Bush Stone-curlew), but these are not included here. All common names and scientific names listed in this booklet (species and subspecies) are consistent with BirdLife Australia's Working List of Australian Birds.

BirdLife Australia recognizes seventeen species of nocturnal birds. Ten of the species presented in this field guide are owls. Within the owls, there are five masked species belonging to the Tyto genus and five Ninox or "Hawk owl" species, distinguished by large yellow eyes. The other Australian nocturnal birds included in this field guide are split between the genus Podargus or "Frogmouths," genus Eurostopodus and Caprimulgus or "Nightjars." and the genus Aegotheles or "Owlet-nightjar."

All seventeen species of the nocturnal birds identified in this field guide are residents; however, a few populations have been reported to migrate locally in response to prey fluctuations and weather changes. Nocturnal birds occur Australia-wide and occupy a large range of habitats. Many species occur in wooded areas, as they rely on prey associated with this habitat type. Prey density and key habitat features like roost and breeding areas determine nocturnal birds territory sixes. Sadly, fragmentation, land clearing, and urban expansion is taking a toll on our night hunters and Powerful, Scooty. Masked and Baring owls all have predicted population sixes of less than 6-3000 individuals.

Identification tips.

Sometimes finding nocturnal birds requires more than your eyes. Listening for mobbing by day birds can help you locate an often highly camouflaged owl or nightjar. You can also find nocturnal birds through the signs of their activity, such as regurgitated pellets or prey remains. Whitewash, the paint-like areas of unrates from feces, is often typical under roosts of many nocturnal birds. To identify which species of bird you are looking at, remember to look at body size and beak shape first, and plumage character second. 

Behavior.

Nocturnal birds are often recognized as hunters by day-active birds and are attacked or shouted at.

Owls and nightjars avoid this mobbing behavior by roosting in secluded, dar, densely canopied places in trees, tree-hallows, and even caves. Some species, such as Powerful Owl, may roost in pairs during the breeding season, which others like Boobook owls and Tawny Frogmouths may roost in family groups.

Threats to nocturnal birds.

Habitat loss.

Nocturnal bird habitat is increasingly at risk from rapidly expanding urbanization and development pressure. Deforestation and habitat fragmentation continue to escalate in Australia's urban and rural areas, with only 16% of Australians now forested.

Many nocturnal birds such as Powerful, Rufous, Masked, and Scooty Owls rely on extensive forest areas and are vulnerable to forest clearing. Nocturnal bird populations will also decline if fragmented forest areas have become too small to support them.

In urban areas, large hallow-nearing trees, which are used annually by most nocturnal birds to nest, are often removed for safety and reduced infrastructure risk. For many nocturnal birds, these old, hallow-bearing trees take several hundred years to develop and are now critical habitat in urban environments, Whilst retaining hollow-bearing trees is essential for many owl species, understorey vegetation important for many other nighty birds.

Grass owl nest on the ground in open grassy areas under tussocks or sedges, whilst Nightjars often next in scrapes on the ground amongst leaf litter. 

Competition for hallows.

Tree hallows are prime real estate in the bird world. Nocturnal birds compete with introduced species over nest hollows, and introduced species can aggressively drive native nesting birds.

Overabundant native species can also pose a risk to nocturnal nesting birds and documented killing young owlets before fledging. European Bees (Apis mellifera) also compete for tree hollows and cause breeding hallows' abandonment.

Pesticides

In North Queensland, Bran, Masked, and Grass Owls populations' population have dramatically declined as pesticides to protect sugar cane crops from rodents have increased. Owls can be killed by ingesting poisoned rodents. Insectivorous nocturnal birds, such as FRogmouth and Nightjars, are also highly susceptible to secondary poisoning, particularly from termiticides. To avoid secondary poisoning, pest control needs to use poisons with no secondary transfer, a single dose rather than multi-dose. 

Urban Impacts 

Urbanization

Nocturnal birds tolerate urban environments differently, with some species being more adaptable than others. The Powerful Owl is an example of an urban nocturnal bird that survives in cities along the east coast of Australia. These owls can do well in forested urban green spaces due to a ready source of prey (e.g., possums, birds, and fruit bats); however, increasing development rates threaten key habitat features like tree hallows roosts. If we wish to keep owls and other nocturnal birds in our urban neighborhood, targeted management practices that work to retain or rebuild key habitat features are essential. 

Collision.

Collision is a major cause of death or injury for urban nocturnal birds; Whilst collisions with vars are most common, collision with grass windows and fences are increasing. There is only a small body of research looking at strike rates in Australia, but in America, window trikes are thought to kill up to 1.3 billion birds per year! Most fatal incidents occur close to breeding sites for car strike injury or death, and when fledglings are still learning how to fly.

In Sydney, the Powerful Owl Project estimates that 85 of Powerful Owls' urban population is lost each year to car-strike. The Project is actively involved in collecting data to reduce collisions and help to develop fauna-friendly roads. 

Disturbance

Flash photography is becoming an increasing problem doe owls breeding in urban areas and is a known cause of nest abandonment for Powerful Owls. Whilst there is no current evidence of its negative impact on owl breeding, flash photography can depress available hunt hours and may be associated with increased defensiveness in owls.

The powerful owl project.

The Powerful Owl Project is a citizen science project that commenced in 2011 to better understand the ecology of the iconic and threatened Powerful Owls. The project came to Queensland in 2018.

The project aims are:

1. Inspire and educate the general public.

2. Train citizen scientists to conduct surveys. 

3. Monitor the distribution, abundance, and breeding success of owls.

4. Uncover why owls are present in areas and habitat associated with breeding success.

5. Develop species distribution models to be used as planning layers by state and council.

6. Identify management recommendations. 

7. Understand the impact of vehicle strike, electrocution, and other threats.

8. Inform and support land management for the conservation of Powerful Owl. 

There are two ways for the public to be involved with Powerful Owl research and conservation:

1. by providing information on Powerful Owl sightings (including injured and deceased owls) and reporting this information to the project;

2.by becoming a trained volunteer to collect important ecological data at allocated breeding sites. 

Thanks

Sofia and Stephanie:)