Dalkey Tidy Towns - Wild Life Newsletter August 2009

Wildlife Newsletter for the Township of Dalkey
August 2010 - Michael Ryan

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Small Farmers
I’d noticed the ants that appeared on the stalks of our artichoke plants for years and had presumed the masses of little black creatures that were fussing around on the stalk were young ants. Then I realised they were actually doing something I’d heard about, but never thought I’d actually witness. These were ants ‘farming’ aphids. The little black creatures were Blackfly, a form of aphid and their diet of plant material produces in them a liquid called ‘honeydew’ which they secrete in a little drop after the ant strokes their back with its antennae. It’s a symbiotic relationship that is one where both partners benefit, between the two species since the ants will protect the greenfly from predators such as ladybirds. When you look closely you can see the ants going up to individual Blackfly and gently stroking them to stimulate them to produce a little drop of honeydew.

Ants ‘farming’blackfly
on artichoke stem

And High Fliers
The most commonly seen gull in winter, the Black Headed Gull, all but disappears from the east coast in early summertime, moving inland to breed around lakes and rivers. They start arriving back in July and later in the summer they can be seen taking part one of nature’s summer spectacles. On windless humid days you might notice a few birds wheeling about in the air. If you look up you’ll notice that it isn’t just a couple of birds but dozens, maybe even hundreds, mostly the aforementioned gulls but other birds as well turning, swooping and diving in the still air. Swallows, House Martins and Swifts always feed in the air but for the gulls this is a special seasonal treat. What turns them into aerial insect eaters is the profusion of flying ants which with a uncanny precision all emerge in there thousands on the same day to take to the air. Most ants don’t have wings but on these days you might see colonies of them emerging from cracks in the pavement or out from under rocks. If you watch them milling about on the ground you can see the object of their attention are much bigger winged ants, preparing for takeoff. These are young female ants, known as Princesses, which are about to set out into the world to start a family of their own. Some smaller male ants will also develop wings and take off to help establish the new nests but they have a short lifespan unlike the female who will give birth to and raise thousands of young. It’s believed that a combination of low winds and humidity triggers the simultaneous dispersal of these insects over a wide range and maybe it’s the sheer numbers that take to the air ensure some will survive. The ants on the ground are like little groups of airport ground crew preparing the females for their big journey, fussing around them, preening the ‘princesses’ wings and maybe offering a few ant words of encouragement. I always think it’s a little sad as these insects set out into the upper sky on their big adventure that hundreds of thousands of them will be snapped out of the air by hungry birds but there’ll always be enough to get through the gauntlet and begin their own colonies.
New Arrivals
The dog suddenly glared very intently at an overhead branch. She didn’t start her usual squirrel bark and then we saw the object of her attention was a Jay, perched on a branch right above our heads. As we watched the jay it moved into the dense centre of the Larch tree it was perched on. Then my companion realised it had actually gone into a nest which was just visible in the very centre of the crown of the tree. We could see a big jay chick looking as if it was about to burst out of the nest and we could see there were more chicks all squeezed in very tightly together. Jays are notoriously secretive birds and we’d walked under the tree dozens of times, totally unaware of the family of one of our most colourful woodland birds a few feet above our heads. Coincidentally, for years a pair of Sparrowhawks had nested on a larch tree a few yards away on the other side of the path, successfully hatching and fledging successive generations of Sparrowhawks, once again a few feet away from a frequently used path. They nested there for many years until the tree, which had grown at a leaning, angle and always looked a few inches away from collapsing was brought to the ground after one windy night. Anyhow we’ve seen the Jay family out and about, at least four noisy juveniles demanding food from their parents. It’s wonderful these beautiful birds have once again nested on Killiney hill and hopefully their offspring will provide future residents for the woodlands

Roseate Tern chick being ringed on Maiden Rock in June

Lucky Box
Last month I said we’d put out nest boxes and gravels for the terns we hoped would return to nest on Maidens Rock off Dalkey Island. We always number the boxes for reference so we can say for example that a particular bird is nesting beside a particular box. Although we didn’t have twenty boxes out we decided to number one of them 21 since in previous years the single pair of Roseates that nested on the rock had gone in to a box numbered 21. Guess what happened this year? Yes, for the first time in three years we had a pair of Roseates nesting on the rock and yes, they did nest in box 21 where they hatched two chicks. After the chicks were able to move the whole family moved into another box further back, maybe to get out of the intense heat of the June sun. After two previous disastrous years when the tern colony was devastated by high seas, this year we’ve had over 25 nests of Common and Arctic terns as well as our one pair of Roseates. Hopefully the north easterly storms will hold off and in a few months a whole new generation of terns will be flying south for the winter?