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Wednesday, 31 July 2019

Invasive Shrew has big effect on Barn Owls

Just two weeks ago, remains of Greater White-toothed Shrews were found in two Barn Owl pellets at a site just a few hundred metres into Co. Kerry, so this fast-invading small mammal is either already in Kerry, or right on the border. Although it had been expected to reach Kerry soon, there have been several 'range jumps' elsewhere this year with evidence from John Lusby that they are now in NE Galway and even Mayo (see this post HERE for more detail on its recent spread.

One of three Barn Owl chicks, just about fledged, at a nest site in a castle in east Kerry (All nest visits and ringing carried out under licence, NPWS. Photo: Michael O'Clery).

As Barn Owl ringing has been underway in the country over the past month it has been increasingly clear that the range of the Shrew is having a big impact on the local breeding success of Barn Owls. In the core range of the Shrew in Tipperary, Limerick and north Cork, Barn Owls have been gorging themselves on them, it often forming 80% or more of individual owls diets. As a result, the well-fed owls are having a bumper year with egg-laying an average of three weeks earlier than normal, and with larger average brood sizes. Two broods of six Barn Owls have been found at two nests in Tipperary, only the third and fourth time this has been recorded in Ireland (the first was in Kerry in 2015, see this post HERE). New sites have also sprung up in this and nearby areas, ie, Kilkenny, and this summer, Barn Owls in at least three sites in the core range of the Shrew are currently attempting to have second broods - the first time this has been recorded in the wild in Ireland.

 Two chicks from a brood of three, Co. Kerry, July 2029 (Michael O'Clery).

In Co. Kerry, where the Shrew has not yet had any real impact on Barn Owls, the picture hasn't been quite so good this summer. As elsewhere in the country, Barn Owls in Kerry have nested on average three weeks earlier than usual, but unfortunately site occupancy has been relatively low and brood sizes about average. So while not a bumper year for Kerry Barn Owls, it's certainly not the worst year they have had.

Some Co. Kerry Barn Owl sites, such as the one above, remain strangely unoccupied. This site has had nesting Barn Owls for over thirty years, but they have not been present for the last two summers despite the nest site remaining suitable and the area surrounded by ideal foraging habitat (Michael O'Clery).

One strange phenomena this summer has been a strong preponderance of male chicks. In Kerry, where the sex could be accurately determined, 11 of 14 chicks ringed were male. It's not known why this might be the case.

A fledged male Barn Owl at a tree nest site near Tralee, July 2019 (Michael O'Clery).

 Although most owls have now already fledged, because of the early egg-laying dates we will continue to monitor nest sites into late summer and early autumn as it's possible that there could still be a second brood in Kerry this year. Let's hope so. 

There seems little doubt that the Greater White-toothed Shrew will have a positive effect on Barn Owls in Kerry in the coming years. Not so great if you are a Pygmy Shrew or Wood Mouse, as both go into serious decline wherever the Shrew invades, but the effect on our Barn Owl population will likely be for the better. It is also likely that Kestrels and Long-eared Owls, and possibly Hen Harriers, are benefiting too. For better and for worse, the Shrew is about to become a permanent and abundant addition to the county's fauna and nothing will stop it now.

Sunday, 28 July 2019

Great White Egret at Baile an Reannaigh

Great White Egret, Baile an Reannaigh, 28th July 2019 (Michael O'Clery).

The tenth record for Kerry, and the third for this site, this one found by Jill Crosher on Friday through a telescope from her house!. A site which has also already seen White-winged Black Tern, Gull-billed Tern, Reed Warbler and Marsh Harrier this year. Not bad, and with the autumn looming... surely more goodies to be seen there.

Great White Egret, Baile an Reannaigh, 28th July 2019 (Michael O'Clery).

Great White Egret, Baile an Reannaigh, 28th July 2019 (Michael O'Clery).

Saturday, 20 July 2019

Long-eared Owl near Castlegregory

Long-eared Owl fledgling, near Castlegregory, 17th July 2019 (Padraig Quirke).

Like Barn Owls, Long-eared Owls have quite a spread in the dates on which they lay their eggs. With Barn Owls, the average date for egg-laying in Ireland is in the first week of May, but Long-eareds average a week or two earlier. Therfore it is usually June when the squeaking calls of young Long-eared Owl chicks are heard but, as some nest earlier, others later, it is possible to hear them as early as May, and sometimes well into July.

Herring Gull Central

Despite still being reasonably common around our coasts, Herring Gulls are under increasing threat, and their overall population continues to decline, so it's good to see one of the larger colonies in Kerry doing well this summer.

The Herring Gull colony is off the coast of the Dingle Peninsula, on the island Máthair na tSearraigh in the centre foreground of the above image. The stack on the left is Shirragh an Searrach (Photo: Michael O'Clery).

Adult Herring Gull, Máthair na tSearraigh, Dingle Bay, July 2019 (Michael O'Clery).

This colony of about 65 - 70 pairs of Herring Gulls is a little unusual in that it is almost exclusively Herring Gulls, whereas many breeding in Kerry will share their nesting areas (mostly on offshore islands) with other gull species such as Greater and Lesser Black-backed Gulls.

Fledgling Herring Gull, Máthair na tSearraigh, Dingle Bay, July 2019 (Michael O'Clery).

Adult Herring Gull with chick, Máthair na tSearraigh, Dingle Bay, July 2019 (Michael O'Clery).

Shirragh an Searrach (Photo: Michael O'Clery).

Up close, the stack is impressive, though the effect is a little dimished when, up close, it is apparent that it is draped with discarded climbing ropes and some tattered remnants of fishing nets. A few pairs of Shag and Herring Gull nest on the ledges on the east side.

Monday, 8 July 2019

More Snowy Owl photos

Snowy Owl, Great Blasket Island, 3rd July 2019 (John Murdock).

Better photos from Great Blasket of the Snowy Owl, the third sighting now as it moved from Great Blasket to near Brandon Mountain on the mainland, and back.

With these images it is possible to say that, with the dense barring on the underparts and what looks like four distinct tail bars, that it is a female (three or fewer tail bars on most males). There appears to be no mottling on the secondaries and outer primary tips (a juvenile trait) so is most likely an adult female, but the quality of the images is such that it isn't quite possible to make out the finest detail. Who knows, it might pop up again for some lucky hill walker and let's hope they are armed with at least a 500mm lens. What a bird!

Snowy Owl, Great Blasket Island, 3rd July 2019 (John Murdock).

Tuesday, 25 June 2019

Maharee islands highs and lows

A couple of visits were made to the Maharee islands in the past week to check on breeding birds and, as is so often the case, there is good news and bad. The bad? Only one pair of Little Terns, and they were flying half-heartedly around the main nesting beaches and heading away for long periods. It looks as though they have failed to nest this year as they are really getting to a point where it would be too late to lay.

One of three small areas of shingle (centre left) on Illauntannig, the only island were Little Terns can nest, and horribly empty this year (Michael O'Clery).

There was a brief mini-revival of Little Tern fortunes on the Maharees last summer, see this post HERE, but really, this species is barely hanging on as a breeding species in the county. 

Little Tern, Illauntannig, 23rd June 2019 (Michael O'Clery).

Little Tern, Illauntannig, 23rd June 2019 (Michael O'Clery).

Also more bad news, the main island, Illauntannig now no longer has any other breeding terns. Arctic and Common Terns have abandoned it, as have all Common Gulls. 

But there was some good news. There were good numbers of Arctic Tern on one of the other nearby islets, perhaps 70 to 80 pairs, sharing the colony with 7-10 pairs of Common Tern and one pair of Sandwich Terns. Not too bad compared to recent years, though far from peak numbers generally around 2005 to 2007.

Some loafing terns at the edge of the main tern colony. Right to left: Two adult Common Terns, a first-summer Arctic Tern and an adult Arctic Tern (Michael O'Clery).

Other good news was that, while Common Gulls have abandoned their former island stronghold Illantannig, they have relocated to another islet, Illaunanoon, and seem to be doing well with around 70 pairs. There were only three pairs nesting here in 2007. There could also be more on some of the other islands not yet visited this summer.

Some of the Maharee islands as seen from the SW looking toward Kerry Head in the distance. Illaunanoon, with the large Common Gull colony, is bottom left. Illauntannig is the larger island in centre middle distance, June 2019 (Michael O'Clery).

Common Gulls, Maharees (Michael O'Clery).

Arctic Terns, Maharees, June 2019 (Michael O'Clery).

Kayakers landing at the tern colony causing all the nesting birds to flush repeatedly and at length, June 2019.

Disturbance on the Maharees is a real issue, and is perhaps the reason Illauntannig is now devoid of nesting gulls and terns (Illauntannig is much the easiest island to land on). However, even during my brief visit, at the newly located tern colony I saw two kayakers land and cause the entire colony to flush, leaving young chicks vulnerable and exposed. The two human intruders really seemed to have no idea that their incursion might be a issue, as they climbed the modest islet and looked around, before settling at the edge of the colony for a sandwich and a sunbathe, seemingly oblivious to over a hundred screeching terns right above their heads.

This sort of disturbance as a one off is unlikely to affect the overall success of the colony, but if it is happening frequently it will surely be to the detriment of the birds. Delicate eggs and chicks can chill, or be exposed to sun or predators. Please people - stay away. A hundred screeching birds dive bombing you are trying to give you a message and it's not that hard to figure it out.

Wednesday, 19 June 2019

Turtle Dove near Tralee

Turtle Dove, Caherslee, Tralee, 19th June 2019 (David O'Connor).

Turtle Dove, Caherslee, Tralee, 19th June 2019 (David O'Connor).

Turtle Dove, Caherslee, Tralee, 19th June 2019 (David O'Connor).

Tuesday, 18 June 2019

Ring Ouzel, MacGillycuddy Reeks

Female Ring Ouzel, MacGillycuddy Reeks, 18th June 2019 (Cait O'Neill).

Ring Ouzels are at risk of extinction as a breeding species in Ireland and it is the highest mountains of Kerry which hold most of the few remaining pairs, in the MacGillycuddy Reeks. Allan Mee has been researching the species for many years and early reports from this spring were disheartening with no birds recorded in the few traditional upland spots in April and May. Allan wrote a fantastic paper in the current issue of Irish Birds journal outlining the plight of this bird (see the BirdWatch Ireland website HERE if you would like to buy a copy), but essentially, the breeding population has fallen from 11 pairs in 2008 to the current estimate of perhaps 2-3 pairs.

Female Ring Ouzel, MacGillycuddy Reeks, 18th June 2019 (Cait O'Neill).

There's a very real chance that this species will no longer be nesting in Ireland in the next few years. Other than Kerry, just one or two nesting pairs hang on in SW Donegal, but the trajectory for both counties has been consistently downward. Several causes of this decline have been mooted... overgrazing by sheep and burning of the uplands has reduced heather cover, a seemingly critical component of a Ring Ouzel breeding territory, especially as cover from predators for fledglings in their first critical weeks of life. A warming climate seems to have made sensitive upland areas more prone to drying out, reducing the adults ability to get at earthworms. 

Another possible cause .. In the past decade I've certainly seen Mistle Thrushes and Blackbirds high up on slopes on e.g.  Brandon Peak, where Ring Ouzels might be expected. Are they occupying marginal high altitude territories because the Ring Ouzels are no longer there to compete? Or as things warm up, are the Ring Ouzels retreating ever higher and their ecological niches being filled by the other two thrushes?

 Another possible contributory cause is increased use of uplands by humans, as Ravens and Hooded Crows increasingly search high peaks for scraps left by hillwalkers, inadvertently leading to higher predation rates on vulnerable chicks. Or are the crows also visiting upland areas more often because of increased stocking rates of sheep? Or all of the above? The answer seems hard to pin down and despite Allan's and others best efforts, the required research is just not being funded. 

Meanwhile, nationally, we are down to just a few remaining pairs. Sobering indeed to think that Cait's excellent series of photos here might be documenting some of the last occurrences of this iconic upland bird in Kerry and Ireland.

Female Ring Ouzel, MacGillycuddy Reeks, 18th June 2019 (Cait O'Neill).

Friday, 14 June 2019

Snowy Owl on Great Blasket

This, the first record of Snowy Owl for Co. Kerry, was seen and photographed by Tom Nisbet near the highest point of the island, on 9th June. Unfortunately it hasn't been seen since though there is plenty of room on the island group, and plenty of prey. Snowy Owls can feed on a wide variety of birds and mammals, so the local rabbits and gulls should be very afraid.

Photo 1. Snowy Owl, Great Blasket, 9th June 2019 (Tom Nisbet).

Photo 1. Snowy Owl, Great Blasket, 9th June 2019 (Tom Nisbet).

The same photo again, but cropped in tighter.

Photo 2. Snowy Owl, Great Blasket, 9th June 2019 (Tom Nisbet).

Photo 2. Snowy Owl, Great Blasket, 9th June 2019 (Tom Nisbet).

The same photo again, but cropped in tighter.

Photo 2. Snowy Owl, Great Blasket, 9th June 2019 (Tom Nisbet).

The same photo, again tightly cropped, but there's a lot more information in this one. Here we can see dense black barring especially on the wings and mantle. So a young male, or maybe an adult female? However, ageing and sexing Snowy Owls is pretty tricky unless there is a lot of detail from good close-up photos of wings and tail. See for example this web page, Project Snowstorm HERE

That website explains; "Ageing Snowy OwlsThe only accurate way to differentiate young snowies from adults is by looking for what banders [ringers] call “molt limits,” contrasts between older, more faded flight feathers, and newer, more blackly marked feathers. This can be subtle, and often requires a trained eye. The degree of barring and marking may decrease with age, as most birders assume, but may also remain the same or even darken — there is a great deal of variability."

and...

"Sexing Snowy Owls: Most birders assume that male snowies are whiter than females, and that is generally true. But the overlap in markings between the sexes is great and confusing. In first-year owls, females have more bars than spots on the middle secondaries, where males have more spots than bars. Female snowies generally have three or more bars on the tail, while males generally have three or fewer, although this is not diagnostic. The terminal dark tail band generally extends from edge to edge on females, but stops short of the edge of the feather in males."

So we can't say for sure what age or sex it might be, but most likely a female or young male.

Doesn't really matter though, does it? It's a Snowy Owl, and that should certainly be enough for anyone lucky enough to encounter such a magnificent bird.

Saturday, 8 June 2019

One good tern deserves another

The Gull-billed Tern is still present as of today, though the White-winged Black Tern at the same spot is now a fading memory. Here's a bit of video to keep it fresh in the mind.

White-winged Black Tern, Baile an Reannaigh, 3rd June 2019 (First clip, Michael O'Clery, second clip, David O'Connor). Click the '4-arrows' symbol for fullscreen.

Gull-billed Tern, Baile an Reannaigh, 7th June 2019 (Kilian Kelly).

Gull-billed Tern, Baile an Reannaigh, 7th June 2019 (Kilian Kelly).

Gull-billed Tern, Baile an Reannaigh, 7th June 2019 (Kilian Kelly).

Gull-billed Tern, Baile an Reannaigh, 7th June 2019 (Kilian Kelly).