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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).