GPS data shows Barn Owl successfully hunts along Motorway verge

Another of our GPS data loggers has recorded the flight of a female Barn Owl in Tipperary hunting successfully along the grassy verge of the M8 Motorway.

The nest site in an abandoned mansion in Co. Tipperary (M.O'Clery, under licence from NPWS).

Inside the nest, two chicks are visible at the rear of a long shaft in a wall cavity, and the backside of a third can just be seen near the top. As this nest was inaccessible, this image was taken using a special nest inspection device to record the number of young (J. Lusby, under licence from NPWS).

She initially takes off from her nest site and, as in the previous post below, hunts along ditches, hedgerows and streams, perching occasionally in trees and on telegraph poles. She hunts along the edges of gardens at one point and perches on a telegraph pole in front of a newly built house for four minutes. About 1.8km from her nest site, after seemingly failing to successfully capture prey, she focuses on the grassy verges of the M8 Cork to Dublin Motorway.

Although she flies along the grass verges, parallel to the Motorway, for about 50 metres, she soon lands on a fence, and within 35 seconds it seems she made a successful capture. We know this because she immediately starts on the return journey to her nest which lies out of sight nearly 2km away, but this time in a direct straight line and at greater speed than when she is hunting. Her return flight does not follow any of the linear features in the landscape which she would use while hunting. The round trip has taken 35 minutes.

Barn Owl hunting along the grassy verge of the M8 Motorway in Co. Tipperary (J. Lusby/M.O'Clery).

The GPS data from this site covered only a relatively small span of time, just over one night, but we can see she made a successful hunting trip to the Motorway verges during that time. Although the GPS data has captured this hunting trip in extraordinary detail, it poses further questions about how Barn Owls interact with major roads and we will be trying to better understand how important road-side verges are for foraging Barn Owls through gathering more information on their behaviour and movements, both at this site and others along the M8 motorway, which is also the route where we have recorded large numbers of juvenile Barn Owls as road casualties.

Screengrab of the point where she meets the M8, and then flies along the grassy verge for 50m. The red dots show where she perched and caught prey (J.Lusby/M.O'Clery).

Using Google StreetView we can see the exact spot where she perched and caught prey on the Motorway verge(circled). She flew directly to her nest nearly 2km away from this point (Google StreetView).

This research is funded by Transport Infrastructure Ireland, with information on the extent of Barn Owl road casualties on the M8 facilitated by Egis Lagan.

More on this very soon.

Seeking out hedgerows

As we start to look through the information generated this season from GPS data loggers fitted on Barn Owls, one of the obvious and consistent features is how foraging Barn Owls seek out linear features in the landscape, particularly hedgerows, and also features such as stream and river edges, woodland edges, and the rough grass of road-side verges. This is expected, but never before have we seen the foraging preference of Barn Owls, and the importance of hedgerows and edge habitats, in such detail.

North Kerry landscape showing typical hedgerow, woodland edge and road margins, vital foraging habitat for Barn Owls (M.O'Clery).

We can see in this video of the movements of an adult female Barn Owl from a nest site in north Kerry. On a night in late July - in this case about 45 minutes of a 75 minute foraging trip - virtually all of her time is spent hunting along these features. 

The female Barn Owl just before release, with the 

data logger just visible above her tail (J.Lusby/M.O'Clery, under licence from NPWS/BTO).

The nest site of this female Barn Owl, in a derelict cottage in north Kerry (M.O’Clery, under licence from NPWS).

With the information recorded on the GPS data logger we pick up on her journey while she is perching in a tree 500m from her nest site. She then takes off to hunt along hedgerow, pausing to perch again on trees and bushes (red dots show where the bird is stationary), and several telegraph poles, where she stops, most likely to listen for prey. The slow hunting flight (orange dots) is almost entirely along hedgerow and field edges, and, with the interior of improved fields virtually ignored, the faster direct flight (yellow dots) is mainly to cross a field to get to the next foraging area along the field boundaries.

Video of foraging flight of a female Barn Owl in north Co. Kerry. The video pauses to show the actual view of the road along which she hunted, perching on each of the telegraph poles along the road, most likely listening for prey (J.Lusby/M.O'Clery, under licence from NPWS/BTO).

More on this very soon. If you wish to be notified about updates, you can 'Subscribe to' or 'Follow' the blog using the menus on the right.

Research on Barn Owl foraging behaviour is funded by Transport Infrastructure Ireland.

New technology reveals Barn Owl secrets

This summer, new light-weight GPS (Global Positioning System) data loggers have been used to track Barn Owls in Ireland for the first time, revealing amazing detail on their foraging behaviour and providing insights on previously unknown aspects such as precisely which habitats birds use or avoid, how birds respond to poor weather, how much time they spend in farm yards, flight height and speed. 

Until now, our knowledge of an individual's movements has been largely confined to the nest site. Nest cameras and nest visits and observations at the nest provide useful information, but once the owls head off to hunt we were, literally, in the dark.

The basis of using GPS data loggers on Barn Owls stems from the need to discover the factors which influence risk of collision for Barn Owls on major roads. Have a look through this blog and you will find many references to road casualties on, e.g., the Tralee Bypass (see HERE).

With this in mind, Transport Infrastructure Ireland and BirdWatch Ireland have initiated research to investigate the extent and impacts of road mortalities on Barn Owl populations, the factors which cause high casualty rates on a major road and whether it is possible to develop effective mitigation to reduce Barn Owl road mortalities. 

A Barn Owl road casualty on the hard shoulder of the M8 in Tipperary, near Cahir, in February this year. Egis Lagan road maintenance staff contracted by T.I.I. record details of all such casualties on a daily basis along an 90 km stretch of the M8 (M.O'Clery).

The lightweight GPS tags are carefully fitted on the lower back of adult Barn Owls (under licence from NPWS/BTO), and are designed to fall off after approximately two to three weeks.  

Adult Barn Owl ready to be released, with the GPS tag in place. It is lightweight enough not to hamper movement or flight, and designed to fall off the bird after about 10 days.(M.O'Clery, under licence from NPWS).

The GPS tag (M.O'Clery).

And what extraordinary revelations are coming from this information. For the first time, we can see exactly where, when and for how long an individual Barn Owl hunts. We can see exactly where a bird perched, for how long, where it next flew to, at what speed, and all with an accuracy down to just a metre or two.

Sample GPS data from a female Barn Owl at a site in north Kerry in July 2016 showing her movements over three nights (J.Lusby/M.O'Clery, under licence from NPWS).

We can see in some cases where a bird roosted for the day (sometimes many kilometres from their nest site), when they resumed hunting that evening, and which habitats they favoured while foraging. We can see where they quartered field edges, or perched in a high tree at the edge of a conifer plantation, and which barn they took shelter from during a downpour.

And what does all this tell us about Barn Owls and major roads? Three sites where birds were tagged had major roads within the owls' home ranges: the M8 was 2km from one nest; the main Tralee to Listowel road was 2km away from the second, and the Castleisland Bypass was 2.5 km from a third. All three Barn Owls hunted during that time along the major roads in their area.

By way of example, have a look below at the movements of a female Barn Owl as she hunts near Castleisland, Co. Kerry, in late July. The video starts with a view of her nest site, but we join her nearly 2km away, at a farmyard where she has been sheltering from torrential rain for four hours. It is now 1.30 a.m. and, as the rain finally lets up, off she goes. We can track her movements as she perches on trees and hedges and then, she arrives at the Castleisland Bypass...

Video showing the movements of a female Barn Owl, Castleisland, Co. Kerry. The GPS device was scheduled to record one fix every five seconds - yellow fixes are where the bird was flying at speed, orange fixes indicate slower hunting flight and red is where the bird was stationary (J.Lusby/M.O'Clery, under licence from NPWS/BTO).
(You can click on the 'four arrows' symbol, bottom right, to see a full screen version of the video)

On one night she hunted along a 1km stretch of the Bypass for 55 minutes, crossed the road six times, and even perched on the central median for 17 seconds! The dangers to the Barn Owl are obvious, however this information also highlights the suitability of road-side grassy verges for foraging. On this occasion  she does does not successfully capture prey, and moves on to forage elsewhere to try and provision the three chicks which are back at the nest site.
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We have a huge amount of information to analyse from this season's GPS data, and there are still other tags to be retrieved, but we will keep you posted with more info and insights as we go...

Jackdaws do Barn Owls a favour

Chimneys make up about a third of all Barn Owl nests and, though they can be in the smallest of cottages or the largest of derelict castles, they are usually only made suitable for the owls by the nest-building activities of Jackdaws.

Jackdaw (M.O'Clery)

From early spring to early summer these industrious crows set about building their stick nests, and when they find what might be a suitable nesting cavity, their instinct is to keep adding sticks until it is full enough to make a suitable shallow nesting platform. In a relatively short time they can fill a large Barn Owl nest box almost to the top with a mix of sticks, lambs wool and various bits of rubbish, tinfoil, twine and whatever else might have caught their eye. In one notable instance, an almost full pack of cigarettes was included in the structure. No doubt some farmer nearby was wondering where on earth his 20 Silk Cut Blue went.

Huge pile of sticks created by Jackdaws, Co. Tipperary, May 2016 (M.O'Clery).

Many a householder who has had to clear the debris of a Jackdaw nest from a blocked chimney can appreciate just how much material can be added and in larger cavities in buildings, such as chimneys and attic spaces, sticks can be added in an almost constant stream, creating some enormous piles. In the example above, the sticks reached a height of eight feet, nearly three metres, inside a derelict house in Co. Tipperary. How many hours of stick-collecting might this represent?

In another example below, Jackdaw sticks dropped down the high, open top of a chimney of a ruined house in Co. Kerry accumulated under the open base, rising to over head height, on top of which was a perfect secluded platform on which Barn Owls nested this summer.

Inspecting a Barn Owl nest on top of Jackdaw sticks, Co. Kerry, July 2016 (M.O'Clery, under licence from NPWS).

So although Jackdaws and Barn Owls are often competing for the same nest sites, Barn Owls are usually reliant on Jackdaws making the chimney suitable in the first place.

Below, some examples of Barn Owl nests in chimneys from this summer, all of which would not be suitable for the owls were it not for the hard work of the Jackdaws.

Three chicks in the blocked  chimney of a derelict mansion, Co. Kerry (M.O'Clery, under licence from NPWS).

This small cottage in Co. Kerry has its chimney blocked by a Jackdaws nest (M.O'Clery).

The same cottage chimney with a female Barn Owl and two chicks on their nest on top of the chimney blockage (M.O'Clery, under licence from NPWS).

Barn Owl chick in its nest site in a castle in Co. Tipperary, an old Jackdaw nest in a chimney shaft (M.O'Clery, under licence from NPWS).

Four Barn Owl chicks deep in the blocked chimney of a derelict house in Co. Tipperary. A perfectly dry and safe nest site (M.O'Clery, under licence from NPWS).

Two Barn Owl chicks in a relatively shallow blocked chimney in Co. Kerry. Such nests can be vulnerable to heavy rainfall, as they offer little shelter from directly above (M.O'Clery, under licence from NPWS).

Nationwide Barn Owl ringing and monitoring underway

A tremendous effort is being made at the moment to monitor and visit as many Barn Owls nests as possible this summer. This is tied in with a large project with BirdWatch Ireland and Transport Infrastructure Ireland (T.I.I) to examine Barn Owl mortality on the M8 Motorway in Tipperary and the Tralee Bypass in Kerry, more of which anon.

Barn Owl chick, Tipperary, July 2016 (Photo: M.O'Clery, under licence from NPWS).

 Results from the nest visits so far have been generally good, with 43 broods ringed so far, and several more to go so, in terms of numbers of broods ringed, it should be a record year. Brood sizes have been mixed, with nests in the Greater White-toothed Shrew range generally faring very well, with typically four chicks in most nests visited so far. Outside the shrew's range in, e.g., Kerry, brood sizes are well down on last year, with generally ones and twos at most nest sites, and only three nests with three chicks recorded so far.

Barn Owl, March 2016, at a roost site  in a castle near Thurles, Co. Tipperary (Photo: M.O'Clery, under licence from NPWS).

Timing of egg-laying this summer is also notably different within and without the shrew's range, with Barn Owls nesting one to two weeks earlier than the average egg-laying date of 7th May wherever they are preying on the White-toothed Shrew, and one to three weeks later in the areas outside the shrew range. Sites in Kerry have been notably late this season with several still on eggs in late June.

Barn Owl chick, Tipperary, July 2016 (Photo: M.O'Clery, under licence from NPWS).

Though the White-toothed Shrew seems to be having a positive effect on Barn Owl breeding numbers and brood sizes, there is still an issue with some nests within the shrew range where the chicks fall ill and die. The pattern is generally that the chicks start to lose weight around 25 to 30 days old, and die - seemingly of starvation - at around 30 to 40 days. Several such nests in Tipperary last week presented a particularly gruesome sight with, in one case, one weak and emaciated Barn Owl chick sharing a confined nest in a chimney with its three dead siblings. These fatalities occur in roughly 10 to 15 percent of nests within the shrew range, and is unknown outside of that, but the cause is as yet unknown. A parasite? Perhaps a virus, or bacteria unique to the shrew which is proving fatal to the chicks. It also seems to be an 'all or nothing' disease, whereby all the chicks in a brood succumb, or all are healthy and well.

Barn Owl nest site (circled) high on the inside gable-end wall of a castle in Tipperary. A site abandoned by the owls in recent years, but re-occupied again this summer. There were three chicks in the nest, all healthy and well fed. July 2016 (Photo: M.O'Clery, under licence from NPWS).

Site occupancy throughout Ireland seems particularly high this summer, with several cases of sites abandoned by Barn Owls in recent years being re-occupied this summer, particularly in counties Tipperary and Limerick. In Co. Kerry, despite the low brood sizes, the number of active sites is at least as high as the record year of 2015. 


Barn Owl nest site in a castle, July 2016 (Photo: M.O'Clery, under licence from NPWS).

Thanks to this years extensive survey work, as well as an increase in the number of nest boxes, an increasing level of contact with interested farmers and landowners, and a huge input from volunteers it looks likely that, by the end of this breeding season in September, we might well have a record number of known Barn Owl sites.

More info on the Co. Kerry sites on the Kerry Birding Blog HERE

An even older wild Irish Barn Owl

Following the post HERE on Ireland's oldest Barn Owl from summer 2015, the longevity record has been broken once more by another Kerry bird.

Ireland's oldest Barn Owl, near Tralee, Co. Kerry, 20th June 2016 (Photo: M.O'Clery, Under licence from NPWS).

This ringed male took up residence at a nest box near Tralee, after the previous veteran male was killed on the Tralee Bypass (see this post HERE), and it was finally possible to read the ring number a few days ago.

He turns out to have been ringed as a chick at a site in east Kerry, about 20 km away, in summer 2008. At eight years of age, this is now the longest-lived wild Barn Owl so far recorded in Ireland.

He is currently paired and successfully nesting in a nest box in a stone barn which contains three young chicks. What he was doing in the previous seven years is a mystery but it would be fascinating to know.

First Barn Owl chicks of the year make an appearance

Although it has been a relatively slow start to the spring for most raptors, Barn Owl chicks have made an appearance at a site in Co. Limerick, the first of the season.

An evocative place - a ruined castle, a full moon, and a nest full of Barn Owls within, calling to be fed, 20th May 2016 (M.O'Clery).

Most Barn Owl sites which have been checked so far indicate that egg-laying and hatching are probably a few weeks later than the average but, at this castle at least, chicks could be heard that were about 10 days old, with others just a few days old. Incubation of Barn Owl eggs is about 30 days, so it looks like this Barn Owl pair set about egg-laying around 20th April. The average laying date for Ireland is about 8th May, though this can vary by three and even four weeks either way in most years.

Results of 2015 National Hen Harrier Survey show declines for Ireland’s skydancer

As one of Ireland’s rarest birds of prey, the long-term declines in Hen Harrier populations provides cause for concern, particularly given the important role this species has to play in our wild and rural landscapes. Hen Harriers are renowned for their spectacular aerial courtship displays known as the ‘skydance’. Traditionally, Hen Harriers breed in open upland habitats, using heather, pre-thicket forest plantations or scrub for nesting while feeding on small birds and mammals. Like many birds of prey, Hen Harriers are a valuable indicator of the health of our countryside. The 2015 National Survey of Hen Harriers (the fourth national survey since 1998-2000) has shown that the national population has experienced further declines, including within some former strongholds for the species.

Female Hen Harrier (Shay Connolly).

The fourth national survey of Hen Harriers in 2015 was undertaken by a partnership of the Golden Eagle Trust, Irish Raptor Study Group and BirdWatch Ireland on behalf of the National Parks and Wildlife Service. Similar to previous surveys the 2015 national survey received enthusiastic support from a substantial network of voluntary surveyors including bird-watchers, farmers, wildlife rangers, foresters and biologists with more than 250 fieldworkers dedicating over 7,000 hours collectively to the survey. This facilitated comprehensive coverage throughout the country and also allowed assessment of new areas not previously surveyed. 

Dr. Marc Ruddock, survey coordinator with Golden Eagle Trust, commented on the efforts involved ‘This is one of the largest surveys of its kind, and would not have been possible without the significant investment of so many skilled surveyors which is nothing short of phenomenal, that so many devoted their time and energy to the survey is hugely positive and demonstrates the passion that is out there to help understand and help conserve Hen Harrier populations in Ireland’. Ruddock continued: ‘to all those involved we extend our considerable thanks and appreciation.’

The current national population estimate of 108-157 breeding pairs in 2015 represents a decline of 8.7% since the 2010 national survey which recorded 128-172 pairs. Due to the increase in survey effort in 2015, the most accurate assessment of national population trends can be calculated through a comparison of Hen Harrier numbers in specific survey squares which were covered across the various national surveys. These results indicate a decline of 16.4% in the national Hen Harrier population since 2010 (based on assessment of Hen Harrier numbers recorded within 139 10km squares surveyed in both 2010 and 2015) and 9.7% declines since 2005 (based on 110 10km squares covered in 2015 and 2005). A comparison of the survey area (78 10km squares) which was covered in all four national surveys (since 1998) indicates that the population has fallen from 110-155 pairs during the first national survey in 1998–2000, compared with 95-130 pairs in 2015, which is an overall decline of approximately one third (-33.5%) over this 15 year period.

Male Hen Harrier (M.O'Clery).

As top predators, the decline of Hen Harriers may be linked with declines in availability of their preferred habitat, changes in habitat quality and associated effects on food availability. It is likely that land-use changes over the past 50 years, which may have resulted in an increasingly fragmented and/or unsuitable landscape for upland breeding birds, may be impacting on the Hen Harrier. Other studies have shown similar declines in upland species such as Curlew and Red Grouse.

In 2007, as a requirement under the EU Birds Directive, Ireland designated six sites as Special Protected Areas (SPAs) based on their national importance for breeding Hen Harriers, including upland areas in counties Clare, Cork, Galway, Kerry, Laois, Limerick, Monaghan, Offaly and Tipperary, which together make up 2.3% of land area in the Republic of Ireland. Management of this SPA network requires that Hen Harrier populations are maintained and enhanced while also being compatible with stakeholder requirements. Supporting farmers and landowners, particularly within SPAs, to manage their lands using traditional and sustainable practices is key to Hen Harrier conservation. 

In 2015, harrier populations in several of the SPA areas were recorded to decline with an overall decline of 26.6% since 2005. Speaking of these trends, John Lusby, survey coordinator with BirdWatch Ireland commented ‘the fact that the SPA network holds 44% of known pairs in the country, which is a significant proportion of the population, shows just how important these areas are in the national context. The current survey results confirm that populations within parts of the SPA network are declining and without intervention through appropriate management further declines at certain sites are anticipated’.

Dr. Allan Mee, survey coordinator with the Irish Raptor Study Group, commented on the specific pressures faced by harrier populations. 'There was a wide range of different pressures recorded in the national survey both within and outside SPAs, and many of these warrant further investigation. Pressures such as forest maturation, clear-felling, wind energy production, agricultural intensification, uncontrolled burning and degradation of important open habitats such as heather moorland, turf cutting, and recreational disturbance were all recorded by observers during the study. Mee continued “It is important to understand why some harrier populations may be declining and thus a comprehensive and scientifically robust action plan is needed to maintain or enhance existing Hen Harrier populations into the future.'

The results of the 2015 national survey will serve to inform the Hen Harrier Threat Response Plan which is currently in preparation through the National Parks and Wildlife Service with input from a wide range of relevant stakeholders. The purpose of this plan is to identify the main threats to Hen Harriers and identify integrated solutions and actions required for a sustainable management of the species. If the plan is successful, it has the potential to deliver an effective framework for conservation of the Hen Harrier and other priority upland birds and habitats.

You can download the PDF of the 2015 National Survey of Breeding Hen Harriers HERE

For further information, contact:

Marc Ruddock, Golden Eagle Trust.   Email: marcruddock@goldeneagle.ie Tel: 087-3578590

Allan Mee, IRSG Chairman.  Email: allanmee@goldeneagle.ie Tel: 087-3117608.



John Lusby, Raptor Conservation Officer, BirdWatch Ireland. Email: jlusby@birdwatchireland.ie

New Shrew spreading fast

A large scale survey of Barn Owls is underway this spring and summer in counties Tipperary, Limerick and north Cork, and in all but one of twenty or so active sites found so far, the pellets of Barn Owls have contained the remains of Greater White-toothed Shrew, a newly discovered invasive species which is spreading rapidly. The implications for birds of prey, and other small mammal species, has the potential to be profound.

Jaw bones of Greater White-toothed Shrew, from a Barn Owl pellet in Tipperary, March 2016. This species is almost three times larger than the native Pygmy Shrew (M.O'Clery).

A collection of jawbones from just one Barn Owl pellet in Tipperary, containing remains of four Greater White-toothed Shrews and one Wood Mouse, lower left (M.O'Clery).

The shrew arrived in Ireland before 2007 possibly around 2004, and by 2013 had spread to occupy an area of 7,600 square kilometres. The source of the invasion has not been established with certainty, though there are a number of large stud farms in the central core area of the shrew, so a possible mechanism for introducing it could have been in the importing of fodder or straw bedding, etc, for the local horse-breeding industry.

Greater White-toothed Shrews (DerHexer, Wikimedia Commons, CC-by-sa 4.0).

In 2012, Greater White-toothed Shrews were calculated to have been spreading at an average rate of 5.5km per year, this rate varying according to local obstructions to its progress such as major rivers, etc. This rate of spread is more than twice that of another invasive mammal, the Bank Vole (estimated to be spreading at 2.5km per year). 

Greater White-toothed Shrews produce up to four litters each year, with litter sizes averaging around seven, and it is the first litter of the year which disperses furthest and is  capable of breeding before the summer is out.

The range of Greater White-toothed Shrews includes most of western Europe - with the exclusion of the Britain - and North Africa, with an introduced population on Las Palmas in the Canary Islands (Wikimedia Commons).

Range expansion of Greater White-toothed Shrews in Ireland, to 2013. The rate of expansion averages 5.5km per year (McDavitt, et al, 2014). 

You can click the map above for closer look.

In the range of the Greater White-toothed Shrew in Ireland, Barn Owls are feasting on them, and they can comprise up to 90% of their diet. Kestrels, Hen Harriers, Long-eared Owls and Buzzards are all likely to be feeding on them, and while the news for raptors at least might initially seem encouraging, there have been some more sinister developments. 

For example, in  areas where nesting Barn Owls coincide with the presence of Greater White-toothed Shrew, the owls were nesting earlier, producing more eggs and larger broods, but in 2012 and 2013, many Barn Owl chicks, fed almost exclusively on Greater White-toothed Shrews, were found to be grossly underweight and often sickly. Whether this was a one-off issue (a parasite, bacteria or other infection) or a more long-term issue now facing Barn Owls is not yet clear.

Greater White-toothed Shrew (Rasback Wikimedia Commons).

Wherever the Greater White-toothed Shrew has spread, records of the native Pygmy Shrew have dropped and then disappeared, judging both from the study of raptor pellets, and from live-trapping. It seems the larger Greater White-toothed Shrew (3x the body mass) is quickly ousting the smaller shrew. Pygmy Shrew has been the only shrew species in Ireland for thousands of years and the speed of the invasion, and the much higher densities which the Greater White-toothed Shrews quickly achieve, means that the Pygmy Shrews have little time to adapt to the new competitor.

Two outlying populations of the Greater White-toothed Shrew have already been found, near Monaghan and on the NW outskirts of Cork City (see map, above), so the rate of spread is likely to increase and it has been calculated it will colonise all of Ireland by 2050. This of course spells disaster for the Pygmy Shrew and it seems it is likely to eventually find refuge only on offshore islands, and possibly peat bogs where it seems to be at a competitive advantage, albeit in low densities. Moreover, where Bank Vole and Greater White-toothed Shrew are found, Wood Mouse numbers have been dropping too.

The long-term effect on raptor populations is uncertain, though there is now nothing to stop the spread of the newcomer. For good or bad, it is here to stay.

A link to the full paper online is HERE.

Citation: McDevitt AD, Montgomery WI, Tosh DG, Lusby J, Reid N, White TA, et al. (2014) Invading and Expanding: Range Dynamics and Ecological Consequences of the Greater White-Toothed Shrew (Crocidura russula) Invasion in Ireland.

A good article on the subject by Michael Viney in the Irish Times can be read HERE.

Barn Owl replacement for road casualty

A visit was made to a Co. Kerry Barn Owl site today, a site where we know a long-lived male was killed on the nearby Tralee Bypass last November. His story is in this post HERE. He used to perch just outside the nest box around this time of year, paying close attention to the female within, hopefully with her about to lay eggs.

And by amazing coincidence, on the exact same beam, almost to the day, just outside the box was a new male Barn Owl, and one that looks like an older bird. Moreover, as you can see in the photo, he is already ringed.

Male Barn Owl, near Tralee, 5th May 2016 (M.O'Clery).

So where might he have come from? Without being able to read the ring, we can't know, but it might be possible to re-trap him this summer. Barn Owls are thought to be sedentary once they have passed their first winter, but if this male is several years old, he might have left another home range to take over at this site, or perhaps he was nearby, unpaired? We are dying to know!

Male Barn Owl, near Tralee, 5th May 2016 (M.O'Clery).

Merlins in Ireland: getting to know our most elusive falcon

From John Lusby
, Raptor Conservation Officer, 
BirdWatch Ireland

Merlin surveying can elicit all the emotions birdwatching has to offer, from exhilarating highs to soul-destroying lows, except usually it is only the latter. If it is appropriate to label a bird as ‘crafty’ then this perfectly describes our smallest falcon. A long day in the remote uplands searching for this elusive raptor typically ends in exhaustion, with wet feet, damper spirits, and riddled with midge bites, but without so much as a glimpse of a Merlin. 

Such memories are short-lived, however, if fool-hardy persistence is eventually rewarded with sight of a Merlin. Frustration quickly changes to privileged admiration in those rare moments when the true character of this predator is witnessed, with incredible agility on the wing in relentless pursuit of its quarry, or ferociously defending its nest from much larger assailants with nimble and fearless confidence. Brimming with attitude, this diminutive raptor commands respect.


Male Merlin 
(Photo: Chris Gomersall)

The same traits which make Merlins so intriguing and elusive also mean that they tend to fly beneath the radar when it comes to prioritising research and conservation resources. Like the forgotten child, Merlins are generally over-looked in favour of the less ‘challenging’ birds of prey.

Status

Most assessments of the status of Irish Merlin typically employ the terminology ‘unknown data’. There has been no national census of Merlin in Ireland. Monitoring of discrete populations has provided some information on their nesting ecology and short term regional trends; however, in the absence of a systematic survey and targeted monitoring, a robust population estimate and overview of the status and conservation requirements of the population is lacking.


Female Merlin 
(Photo: Dick Coombes).

Breeding range declines of 8% and 49% over the past 20 and 40 years recorded by the bird atlases have been the primary source used to categorise Merlin as an Amber-listed Bird of Conservation Concern in Ireland. However, due to difficulties in effectively assessing the population, multi-species surveys such as the bird atlases are not likely to provide an accurate representation of Merlin status and trends.

As an Annex I species on the European Birds Directive, the Merlin is a national conservation priority for which there is a requirement to ensure the protection of the population. Six Special Protected Areas (SPAs) have been identified with Merlin as a Special Conservation Interest in upland areas thought to be strongholds for the population; however, the importance of the SPA network for Merlins and how they are performing is not known. What is clear is that in order to understand the requirement for conservation action and to develop an appropriate management strategy for Merlins, it is first necessary to gain an insight to their status and the factors which impact the breeding population, all of which remain knowledge gaps in Ireland.

Conservation Concerns

The Merlin has a widespread but sporadic distribution across upland habitats in Ireland, where they occur in low densities. As with a range of other upland bird species, the land-use changes and intensification of agriculture which have altered upland areas over recent decades are likely to have impacted breeding our Merlins. As an open country predator which specialises on open country birds, Merlins may be especially vulnerable to the loss or degradation of suitable open habitats. Alongside a substantial reduction in heather cover, widespread afforestation in the Irish uplands has therefore given rise to concerns for Merlin populations.


Merlin chicks in the nest in Connemara
 (Photo taken under NPWS licence)
 (Photo: John Lusby).

The relationship between Merlin and commercial forest plantation is complex, however, as plantation forests can provide opportunities for nesting while at the same time limiting the availability and suitability of habitats for foraging. In Britain, where Merlins have been more comprehensively monitored, there is conflicting evidence as to the impacts of afforestation on their populations. In Ireland, afforestation has progressed at one of the fastest rates in Europe, and has been primarily concentrated in upland habitats. As a result, Irish Merlins are now likely predominantly to occur in forested landscapes, and key to developing an effective conservation strategy will be understanding the impacts of afforestation as well as forest management activities on our Merlin populations.

Survey and Monitoring

A range of tactics can be employed to locate breeding Merlins, all of which require painstaking effort and patience. When surveying in suitable habitat, you are acutely aware that a sharp pair of eyes is likely to be observing your struggles from a discrete vantage point. One of the best survey methods is searching not directly for the birds themselves but rather for the “plucking” remains of their prey. Although Merlins will take moths and dragonflies, their main prey is small birds such as Meadow Pipits and Skylarks which are generally caught after high speed, and sometimes quite drawn out and exhaustive, “tail-chases”.


Merlin plucking post with remains of prey items (Photo: Dermot Breen).

After a successful capture, a Merlin will take its prey to a prominent look-out such as a boulder or hummock, where prey will be plucked before being consumed or delivered to the nest to feed voracious chicks. Investigating potential plucking perches can reveal evidence of recent kills and indicate the presence of Merlin in the area. However, a pilot Merlin survey showed that the effectiveness of this survey technique can vary between sites, as extensive searches of known breeding territories have revealed little or no signs of Merlins.

It was hoped that the pilot survey undertaken by BirdWatch Ireland and the National Parks and Wildlife Service in 2010 would be a pre-cursor to a national census. However contrasting assessments of Merlin occupancy and breeding status in the same areas by different teams of experienced surveyors highlighted that a national census for Merlin could not be carried out in the same manner as those for Hen Harrier and Peregrine, which involved a large volunteer network, and that a different approach would instead be required.

In recent years, monitoring efforts have focused on Connemara. Here Merlins nest on densely wooded islands on the many lakes scattered throughout the vast areas of bog. Covered in Oak, Yew, Holly, dense mosses and ferns, these tiny remnants of natural woodland seem like they belong in a fairy tale, and are in stark contrast to the swathes of non-native coniferous monocultures which dominate large parts of this landscape.


Merlin chick in the hand, prior to ringing 
(Photo taken under NPWS licence) 
(Photo: John Lusby).

Although the nesting preferences of Connemara Merlins make survey work marginally easier than searching for pairs in extensive forest plantations, they presents its own unique set of challenges. Traipsing across the bog in a wetsuit with fins hanging over shoulders on a hot summer day may garner strange looks from farmers and walkers, but this has proven to be the most suitable attire for effective surveying. 

In an attempt to increase the efficiency of monitoring, some novel survey techniques have been trialled in Connemara, including broadcasting Merlin calls and using a decoy to try to elicit a response from resident birds, both of which had limited success. Artificial nest baskets, which have been successful in other parts of the Merlin’s range, have been installed at suitable sites across Connemara, but true to character, Merlins have not shown interest, with the baskets proving to be more appealing to Long-eared Owls.


Merlin nest in Connemara, containing five eggs 
(Photo taken under NPWS licence)
 (Photo: Dario Fernández-Bellon).

New Research

Although there have been few published studies on Merlins in Ireland, over the years a small number of dedicated fieldworkers have devoted significant energy to gathering information on local Merlin populations in different areas of the country. In collaboration with these original surveyors, BirdWatch Ireland and University College Cork collated available information which for the first time provides a broad overview of long-term breeding trends and habitat use of Merlins in Ireland extending over the past thirty years. Analysis of over 340 breeding attempts monitored since the early 1980s shows that Merlin breeding trends have remained relatively stable over this period. Traditionally Merlin nested on the ground in heather moorland in Ireland; however, this study confirms that ground nesting is now exceptionally rare, with only a single pair recorded in moorland and all others nesting in trees, the vast majority of which were in conifer plantations.

The lack of suitable heather cover is likely to influence nest site choice, but despite the fact Merlins showed a strong selection for forest plantations for nesting, a positive selection for moors and heathland, peat bogs and natural grasslands within breeding territories also demonstrates the importance of these open habitats. As well as providing information on the landscape and habitat requirements for Merlins in Ireland, the findings on nesting preference also highlight that they are vulnerable to disturbance from forest management operations, and this study now provides the necessary information to develop the required mitigation. Although study provides positive progress towards a better understanding of Merlins in Ireland, it is a case of ‘a little done, a lot more to do’.


Female Merlin
 (Photo: Shay Connolly).


Research on Merlin breeding ecology and habitat use was undertaken as part of the ‘Avian Diversity and Afforestation Planning Tools’ project at University College Cork and BirdWatch Ireland, which was funded by the Department of Agriculture, Food and the Marine in Ireland. This study was possible due to the collaboration and contribution of data from NPWS and independent Merlin surveyors, with particular thanks to Larry Toal and David Norriss.