Eerie Calls in the Night

I have been out on the prowl, over the last few nights trying to track down breeding Barn Owls. With most of the countries breeding population monitored at this point in the season, I am simply seeking some of the remaining outliers, to create a fuller picture of breeding status of this Red-Listed Species. Several of these sites have proven active and even seem to have bred, which is a positive in what has been an all round bad breeding season for many species.

Barn Owl - pictured by Padraig Cregg

Last night I visited a large ruined mansion not far from Banagher. The fact that the building wasn’t far from a road which gets a moderate level of usage allowed me some leeway in terms of my approach. I needn’t have worries though as I could hear calling Barn Owls has soon as the chunky thud of my diesel motor subsided. I could hear four birds in total, but it can be hard to be precise on the number of birds present as they may simply be moving about. I definitely saw three owls. My best guess was that there were two fledgling Barn Owls who were flying about along with their parents. The parents were calling back and forth to one another, a behaviour more typical of earlier in the season. This renewed courtship could result in a second breeding attempt by the parents, but given the bad season it is unlikely that it will amount to much. Barn Owls can have a second brood in a year but this is quite unusual in Ireland. In fact a brood as late as October has been recorded by BirdWatch Ireland staff.

Barn Owl white wash - pictured by Padraig Cregg

Although of course a nocturnal species, day time visits to likely buildings can be very informative also. Should you hear the stereotypical snoring begging call during the day it is most often a sign that the chicks are still quite young. Pellets and white wash, are, though the main daytime signs to watch out for. Above is a picture of Barn Owl white wash, note the thin white line almost like a dribble of white paint, which identifies it as Barn Owl white wash. Once birds are seen to be present, through day or nighttime observations, the building is revisited to ring the occupants, pictured below.  

Barn Owl ringing - pictured by Padraig Cregg

The Peregrine Falcon

The Peregrine Falcon is a beautiful bird, I think few would argue, but man-o-man what an ugly alarm call. I have been diversifying to a degree of late, moving away from my usual fair of Owls and Kestrels to the more regal Peregrine. Sitting atop their food chain has instilled a confidence to the species which other smaller raptors lack. Whenever I approach a nest site, the resident pair circle and berate my intrusion with their alarm calls. As with Barn Owls and Kestrels, ruined builds are an important nesting site for the species. Before entering into this field of work I would never have imagined or probably of have noticed the sheer number of ruined castles, mansions and cottages in the country. This second life of the buildings, makes them of great conservation importance. Fledgling Peregrines below.

The inside of a Peregrine occupied ruined building, is a veritable who’s who of the local avian community. The ground under foot crackles, with the crunch of miscellaneous bones of past meals. Although Peregrines are often implicated as racing pigeon glutens, Jackdaw carcases in my experience make up a large chunk of the diet. This is an unsurprising chose on the part of the Peregrines, due to the fact that Jackdaws are often also in residence in the ruins.

A lot of fiction surrounds Peregrines and the speeds which they can reach during a stoop while hunting. Let me try and clear this up, between 160km and 410km has been suggested by various authors. The truth is that birds have been seen to reach speeds of 200km and that speeds of 240km are theoretically possible for the species! During the stoop, Peregrines drop from a great height, folding their wings back and slightly away from their bodies, creating a tear drop shape. The unsuspecting prey is often killed in the midair collision, with the Peregrine’s talons aiming for the head. If the prey is still alive after collision, it is dispatched on the ground with the beak.     

Peregrines are a real success story; with the changes in the laws controlling the use of pesticides the species is making a comeback. Being both an urban and rural species, a close encounter with a Peregrine could be just around the corner, why not keep an eye out in your local patch for this sleek speedster.

Dusk on the Shannon, and all is well with the world.

The Shannon - by Padraig Cregg

Irish Stoat

I was on the way to work when a flash of brown, sped across the road. It was a stoat, with a rodent in its mouth. In its surprise and haste to avoid my car wheel it dropped its prize. Knowing their cheek, I pulled over, jumped out of my car with my camera in hand just in time to get this shot of the stoat returning to retrieve its meal. The Irish Stoat, which is an unique sub species, can be identified by the ragged edge of white on the chest, as apposed to the smooth edge seen on continental stoats.

Irish Stoat - by Padraig Cregg

Starving

I spoke in my last post of the introduction of two new small mammal species, this week I have seen firsthand the devastating effects on Barn Owls.

I have been ringing Barn Owl chicks at nests in Tipperary and east Limerick in the past few days. The chicks which we have been finding have been in very bad health and perilously under weight. The chicks are lethargic, under sized, their feathers are not as developed as they should be for their age and light. So light in fact that little hope can be held out for the survival of many of the individuals encountered. Some of the chicks we found weighed just over half of the appropriate weight expected for their age. The brood sizes were also depressed. Many of the nests contained the grizzly, mummified remains of nest mates who hadn’t made it. Chicks often seemed to be experiencing some form of intestinal problem; covered in faecal matter, the smell would turn your stomach.

What on earth is going on with these Barn Owls?

Firstly let me lay out a few facts. This area of Tipperary and east Limerick is the strong hold of one of our latest small mammal species arrivals, the Greater White-toothed Shrew. The Greater White-toothed Shrew occurs at very high densities within this region. Where this species occurs in any great numbers it constitutes the majority of the diet of the Barn Owl. Barn Owl chicks in this ‘Shrew Zone’ are being feed predominately on Greater White-toothed Shrews. These facts seem to implicate this Shrew species. Furthermore, the fact that this shrew species occurs at such high densities in the area would suggest that it isn’t quantity of food which is the problem for Barn Owls but quality.

Following this line of inquiry BirdWatch Ireland in collaboration with Queen’s University are examining the nutritional value of the Greater White-toothed Shrew. Well feed chicks that are starving to death seems counter intuitive, although a comparable situation has been well documented among men who found themselves isolated in the Canadian wilderness. Over a hundred years ago when people used to spend the winter trapping for fur in Canada’s vast wilderness they would subsist on a diet of hare meat. These men would then often starve to death, although they were seemingly well feed. The problem resides in the fact that although hare meat is nutritious in many respects, it lacks many essential vitamins and minerals. The men were expending more vitamins and minerals in digesting the hare meat than the meat was providing in return!

Could Barn Owls be experiencing a similar paradox, only time and further research will unlock this riddle.