Tuesday 19 January 2016

Irish Bird Ringing Data - Owls

In Ireland we generally have three breeding species of Owl - Barn, Long-eared, Short-eared Owls and have had a couple of rare visitors in Little, Scops and Snowy Owls.   Little Owl is the only species not to have been ringed and the minimal records may have been as a result of a failed, non official, introduction.
A single Scops Owl was ringed in Ireland in 1999 at Cape Clear - a further 8 have been ringed in Britain since 1909. 
The Snowy Owl is a rare winter visitor to Ireland, although the odd bird has taken up residence out west and they have even attempted to breed.  The data is a little unclear as there are suggestions that there were four pullus ringed in 2002 but the BTO don't seem to have a record of this.  A pair was confirmed to have attempted breeding in 2001 but failed with four eggs, so the potential is there, but unlikely.  There was certainly one adult male Snowy Owl ringed in 2002.  A total of 29 have been ringed in Britain since 1909, although the majority of these were nestlings from the breeding pair in Shetland between 1967 and 1975.     

Barn Owl

Across much of Ireland the Barn Owl is a scarce breeder with the greatest concentrations in the southwest.  There are as few as 40-50 pairs across the whole of Northern Ireland.

A total of 670 Barn Owls were ringed in Ireland since 1977 and you can see from the graph below that it is in the past eight years when the majority were caught.  This data is not representative of populations but is down to the real effort made by the guys in Duhallow (more info below) and also the erection of hundreds of owl boxes.  Of those birds ringed, only two were caught in Northern Ireland.  A further two were ringed in 2015 when Barn Owls bred in an owl box in Northern Ireland for the first time.  Many more boxes have been going up in suitable locations in the past few years and it is hoped these will help boost the breeding populations.  There's nothing much we can do with the wet & windy Irish climate and the lack of voles but we could improve the habitats and cut back on poisons/toxins.   

Ringing recoveries show a main movement of birds from southwest Scotland, with four birds ringed as nestlings in Dumfries and Galloway relocating to Ireland.  The Welsh bird from Anglesey was also ringed as a nestling.  The bird ringed on the Yorkshire coast is interesting because it was a first year bird when it was trapped in mid September, although there are no details in regards to race.  The European race 'Dark-breasted' Barn Owl (Tyto alba guttata) has been recorded in Ireland but long distance Barn Owl migration still remains a rare occurrence across the world. 
All of the recoveries have been in relation to dead birds with four road casualties, one hit by a plane and one long-dead in a derelict building. 

Barn Owl movements into Ireland

The guys in Duhallow have been doing some great work on Barn Owls and other raptors in recent years and probably account for the majority of Barn Owls ringed in Ireland - check out these blogs for more info...

Long-eared Owl

                           Long-eared Owl                            (JC)

LEO is the most common and widespread Owl in Ireland but is seldom seen because of its inconspicuous nocturnal nature.  The numbers are boosted in winter when there is an arrival of birds from the north/east.
Since 1975, 151 LEO have been ringed in Ireland with at least 50 of those ringed in the north.  Before this period there were five ringed at Copeland BO & two at Cape Clear BO.  There are no obvious trends in the catch graph, but like Barn Owl, this will be down to effort by ringers.  Adult LEOs are quite difficult to catch and many of the records of these refer to birds caught at the coastal sites on migration.  The majority of the records are pulli ringed in nests and with clutch sizes up to six eggs, it can really increase the number caught in one year.

The recoveries of Long-eared Owl into Ireland are rather few but they do show a nice range of the movements.  The first of these comes as a passage migrant from Helgoland, Germany, which could have potentially come from anywhere but most likely out of Scandinavia via Denmark.  The second bird came through Orkney and probably made the jump from Norway.  Both these birds were caught in subsequent years after initial ringing, so possibly could have migrated multiple times but it is difficult to say.  The third bird was ringed in a nest in central Scotland and was recovered in its first winter. 
The only movement out of Ireland was a bird ringed as a chick in Phoenix Park in Dublin, which was controlled at the Calf of Man Bird Observatory.  It is perhaps not a movement you would expect, with the bird heading north east in November in its second year. 

Long-eared Owls movements into and out of Ireland

Short-eared Owl

The SEO is generally a winter migrant to Ireland, with birds from Scandinavia and Scotland. One or two pairs breed every other year in some of the upland areas.  The Antrim Hills have been a relatively reliable area since 1997.  The success is said to be down to the accidental introduction of Field Voles into the area via bags of conifer saplings, brought over by a Scottish forestry company.  The proximity to the breeding birds in Dumfries and Galloway and the Scottish Borders probably boosts the Irish breeding population.
During the period of 1977 to 2014 there were only 10 SEOs ringed in Ireland, all in the south, plus at least one ringed in 1965 and at least one caught in late 2015 - more information on this bird is available below

Like the LEO, there are only three records (available to me at least) of birds moving into Ireland.  The only foreign recovery was a bird from Ikaalinen, Turku-Pori, Finland in an impressive movement of at least 2311 km.  This bird was ringed as nestling in June 1988 and recovered dead the following April in southwest Cork.  The other two birds were ringed as chicks in central Scotland and both headed to Ireland in their first winter, and as with most owls, were found dead, unfortunately the bird in Wexford was shot.  It would be quite interesting to know where Irish born SEOs go...

Short-eared Owls movements into Ireland

Potentially there were five Snowy Owls in 2002 but I can only confirm one, so I am being cautious and including just the single bird.  

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