Territorial Owls Give the Game Away

Long-Eared Owls (pictured below by Richard T. Mills) are rarely, if ever seen. They are nocturnal, have cryptic plumage and a secretive nature. How then does one survey for the presence or absence of breeding individuals? Previous studies have relied on late summer visits, to likely nesting habitat, after dark to listen out for the begging calls of young Long-Eared Owls. The calls are described as, akin to the sound of a rusty gate closing. Using this technique, however, failed breeders are over looked. To overcome this The Raptor Conservation Project of BWI has rolled out a playback survey. This will represent the first such undertaking in the state.

The survey aims to establish breeding densities of both successful and unsuccessful pairs of Long-Eared Owls within the 10km squares surrounding the West Offaly towns of Banagher, Ferbane and Belmont (IN01, IN12 and IN02 respectively). This project also aims to assess the effectiveness of the playback technique in Ireland and to provide data on the ecological requirements of the species.

What exactly is a playback survey? The concept itself is not a new one it is used in many parts of the world, for many different and contrasting species. In essence the technique relies on the territorial nature of many species. Raptors particularly can have strong territorial tendencies. By broadcasting the calls of a con-specific, a member of its own species, it is hoped that any resident birds will respond with a corresponding call or noise of some sort. This technique finds its true value for elusive species such as our study species the Long-Eared Owl. In practise I visited each accessible 1km square, of each of the 10km squares and broadcast Long-Eared Owl calls as close as possible to the centre of each (I undertook this survey under licence from the National Parks and Wildlife Service and with the use of best scientific practices). Responses varied from one coo (the male call) to a full blown aerial barrage of coos and wing claps circling over head (a territorial behaviour of males). Females also responded, on occasion, producing a nasal sounding call.

By revisiting each of the 10km squares in late summer to listening for the begging callings of young Long-Eared Owls (below), comparisons can be made to calculate the effectiveness of this playback technique. Success with this technique for surveying Long-Eared Owls in West Offaly could prove of great importance in assessing the national population of the species.

Barn Owl Survey

This survey aims to establish breeding densities of Barn Owls across three 10km² areas in West Offaly. The squares selected for this survey are, IN 01 which encompasses Banagher and its surrounding town lands, IN 02 which has Belmont as its centre and IN 12 which has Boora Parklands just to its south and Ferbane in the west of the square. Results from this strategic survey, along with that of a mirrored project being undertaken by my colleague Michael O’Clery in Duhallow¹, are hoped to provide inference as to the national population of breeding Barn Owls in Ireland.

Specifically, how does one survey for Barn Owls?

Each 10km square is surveyed individually, by travelling across the square and assessing all building’s suitability for Barn Owl nests. Although Barn Owls do on occasion nest in tree cavities, it was deemed unfeasible to survey trees for the purposes of this survey; an account of this will be taken in the final analysis. A suitable building for a Barn Owl must at a minimum provide a cavity for the nest site and have low levels of disturbance. This is most often found in ruined buildings where an old Jackdaw’s nest provides a platform within the chimney (Barn Owls pictured in a chimney below). Other favoured sites are crevices which provide access to a wall cavity in a ruined castle or mansion house.

Having at this point eliminated all unlikely buildings, promising buildings are now surveyed in detail; with permission to enter received from the owner. Likely buildings are meticulously searched for any and all evidence of Barn Owl activity. Any chimneys on site are examined for the presence of old Jackdaw nests, the interior and exterior walls are inspected for white washing (this can look like drops of white paint on the walls) and the property is scrutinised for pellets (Barn Owl pellets pictured below). Pellets are regurgitated hair and bone fragments which the owls cannot digest². If fresh pellets are found in the building it is flagged as potentially active and a roost watch is undertaken. All suitable buildings, however, even if found unoccupied, are recorded; thereby quantifying nest site availability within each 10km square.  

As Kestrels, Peregrine Falcons, Ravens and Jackdaw all frequent similar haunts, any of these species found on site are also recorded. Given the inaccessibility of Barn Owl nests predation is unusual, however, Pine Martens can access nests and, as such, evidence of their presence is also recorded for predation risk models.  

^1. John Lusby, Raptor Conservation Officer with BirdWatch Ireland said “Duhallow, which is an area encompassing parts of North Cork and East Kerry seems to be particularly suitable for Barn Owls, the local population appears to be doing well here and we have recorded one of the highest known densities of nest and roost sites in the country. Given the fact that Barn Owls have declined so markedly in other parts of the country, areas such as this are crucial for the conservation of the national population”

^2. These pellets provide an invaluable insight into the diet of Barn Owls. Individual bone fragments can be identified and a catalogue then created of the species on which the owls prey. In 2008 a discovery of some interest was found in Barn Owl pellets in Co. Limerick. A previously unheralded alien species, the White-toothed Shrew was discovered through pellet analysis to be resident in the locality.

Raptor Study Underway

West Offaly is to host a detailed raptor survey over the coming months. This BirdWatch Ireland project has been funded by Banagher Local Development Company in collaboration Banagher Tidy Towns through the LEADER 2009-2013 programme. The project aims to establish breeding densities of three raptor species in the area. Barn Owls, Long Eared Owls and Kestrels have not been studied in such detail in the area and the results will provide invaluable insights into the current status of the three species nationally. John Lusby BirdWatch Ireland Raptor Conservation Officer stated “despite the fact that these raptors are still widespread and relatively common there have been virtually no specific studies on these species in Ireland, and as a result we are lacking information on even basic aspects of their ecology”. Specifically the project will aim to locate nest sites for the three species and monitor the success of any breeding attempts. A nest box programme will also be rolled out to provide additional nest sites and to aid monitoring.

Until quite recently our knowledge of Barn Owls in Ireland had been relatively limited. The elusive nature of this iconic species meant that it was extremely difficult to gain an overview of the issues that impacted upon these owls. Thankfully this situation has changed dramatically over the past five years largely due to the tireless efforts of volunteers who have facilitated the comprehensive monitoring of Barn Owl populations throughout the country. As a result of their hard work, co-ordinated by the Raptor Conservation Project, we now have a much better understanding of the ecological requirements of our Barn Owls and the factors which affect their conservation status. The success of this project has provided a blueprint for current undertakings.

West Offaly is ideally suited to a raptor monitoring scheme owing to its unique ecosystems, with particular reference to the Shannon Callows and the restored bog of Boora Parklands. The locality supports a wealth of biodiversity including a healthy raptor population. Although West Offaly is well known for the beauty of its landscapes and wildlife this project aims to further encourage an active and meaningful engagement with wildlife. The aims of the project will be achieved through four individual project components, each of which are interlinked and feed into one another.   

Detailed survey work will be carried out within specially selected areas within West Offaly and aims to identify roost and nest sites for Barn Owls, Long-Eared Owls and Kestrels in order to establish breeding density in the region. The public are encouraged to help by contacting BirdWatch Ireland with sightings of any of these key species. Posters detailing the project with relevant contacts will be circulated where appropriate. The farming community in particular are encouraged to participate given their invaluable knowledge of the local countryside. Nests that are discovered will be monitored and chicks will be ringed under license from the National Parks and Wildlife Service.

A nest box and basket scheme will also be rolled out for the three species. The provision of nest sites provides a tangible management system by which local raptor population can be conserved. Nest boxes and baskets provide a safe, secure nest site in areas of suitable habitat where natural sites may be limited. Local groups will construct 20 nest boxes for Kestrels and Barn Owls and 10 baskets for Long-Eared Owls. The work of these groups will prove to be a great help to future monitoring and conservation efforts for Barn Owls, Long-Eared Owls and Kestrels in West Offaly. Previously carried out survey work will highlight suitable locations where artificial nest sites can be placed.

Another exciting element of the project will the use nest camera both for research purposes and to provide the local community with a window into the world of breeding raptor. It is hoped that everything from incubation, the subsequent hatching and rearing will be caught on camera. It is hoped that the system will provide live footage on the internet. It is purposed that this element of the project will be rolled out in 2013.

All questions on the project or sightings of Barn Owls, Long-Eared Owls and Kestrels can be directed to Padraig Cregg by email at pcregg@birdwatchireland.ie or by phone at 087 7866357.