 Dalkey Tidy Towns |
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| Dalkey Tidy Towns |
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Wildlife
Newsletter for the Township of Dalkey August 2011 - Michael Ryan |
| The Sparrowhawks moved from Killiney Hill to nest on Dalkey Hill this year, the young birds taking their first flights in early July. I hadn't’seen the Jays for weeks but the parks staff had been seeing them regularly feeding on the bait of acorns and peanuts left out for the grey squirrels. By early August many of the Swifts that dart across the warm air on summer nights will already have left, on their way south to spend winter in the African skies. Totally dependent on flying insects which inhabit the higher air, as the days get shorter and cooler their inner clock will tell them it’s time to go. A major food source for swifts is spiders. For anyone who has a phobia about spiders it might be disturbing to think that there might be thousands of them drifting in the sky above but many spiders disperse through the air. The spider standing upright on the ground or on a higher perch sends out a thread of silk which waves in the air above it until the breeze catches it and it drifts up into the sky carried to a new location, unless it’s snatched by one of those swifts or some other hungry bird. Swifts seemed to be having a few bad years especially those recent summers which consisted of long periods of cold wet days. On those days it was hard to imagine there could be any insects in the air but swifts have two useful traits which help them adapt, the ability to fly at great heights above the rain clouds and the ability to lower their metabolism so they’re flying in a virtual semi stupor while using very little energy. An experiment in Sweden in 1979 involved taking swifts from their nesting colonies and releasing them with tiny altimeters attached to their backs. |
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| Eight swifts released 405 kilo meters from their nests returned the following day. They were able to establish that four of the birds had flown at heights between 1230 and 2750 metres at an average speed of 40 km's per hour. The highest altitudes reached were by swifts roosting, literally sleeping in the air, at 3,600 metres! Anyhow the good news is that swifts seem to be around in much higher numbers this year. Dalkey quarry is one of the best places to get good close up views of them especially on humid windless evenings when the heat from the rocks must fill the air with insects. From the corner of the path above the easternmost quarry the screeching swifts swoop low, often a few feet above your head. I’ve often wondered at the sound of ravens heavy wing beats passing overhead and the thrillingly dramatic sound of a swooping peregrine (which once gave the dog quite a shock) but this was the first time I’d heard the sound of the swifts sweeping by. Apart from spiders another insect you wouldn’t normally associate with flight is the ant. At the time of writing, mid July, we hadn’t seen it yet but certainly by August there will be days when the sky will seem to be filled with wheeling and swooping Black headed gulls, Swifts, House Martins and Swallows. This happens on very humid, still days when young female ants, known as Princesses, and male ants, known as drones will take to the air on newly developed wings. Almost simultaneously around the country thousands of ants will have appeared from under walls and rocks and mill about preparing the much larger Princesses for their inaugural flight, fussing around them and preening their wings. |
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The
fact that lots of different colonies take to the air at the same time means
the females can mate with ants that aren’t closely related to her.
She mates in the air with the males that are strong and fast enough to catch
her another way of improving potential genes. The drones will die soon after
their flight but the Princesses will land, start a nest and clip off her
own wings as a source of protein for the hundreds of ants her eggs will produce.
Although apparently our coldest summer in 25 years it wasn’t a bad
one for birds with the good weather in early spring helping our early nesting
resident birds. Many birds will produce a few families, or broods, in one
year especially if the weather provides a reliable source of food. In early
July the wren which had nested under the eaves near our back door was feeding
either its second or third family. With binoculars we could see the little
yellow mouths of the chicks gaping wide whenever the mother flew up. Her
initial caution at approaching the nest when there were any humans around
had been surpassed by the chorus of hungry offspring demanding to be fed
and she was constantly taking up beaks full of insects. Safe from predators
all seemed well and hopeful for her little family. Walked around the corner
from the nest and there was the body of a tiny wren on the path. Presumably
pushing too hard for a mouthful it had fallen from the nest. I picked up
the little body, cold and limp with eyelids shut. Although it seemed lifeless
I cupped it in my hand and breathed on it. This often works on woodlice which
appear to be dead. |
| Even if they’ve been floating for days in a rain filled container they often recover after a few warm breaths. I wasn’t hopeful for the baby wren but it did begin to move and was soon opening and closing it’s bill. It only had beginnings of feathers and a tiny stump of a tail but I thought if it rallied a bit I could put it back in the nest. I cut up bits of ham into the tiniest pieces I could hold. Whenever the other chicks in the nest outside would begin calling for food this little one would open its bill as well. I placed tiny pieces of ham on its bill but it didn’t seem to be swallowing any. I was in a bit of a dilemma wondering if I put it back in the nest would it survive but I knew I couldn’t feed it. I placed the ladder against the wall beside the nest and while I was up there I cleaned off the accumulation of ‘guano’ which had collected at the opening of the nest box. The mother bird removes the faeces the young produce in a little pouch but she’d have needed a little hammer to remove this stuff. The nest box accommodates up to eight adult wrens in cold winter nights who poke their rear ends out to relieve themselves and that’s what caked the entrance but inside the box I could see fresh green moss lining the wall. The mother wren had decorated the ‘nursery’. Not a peep from the chicks inside who only respond to the calls the mother wren makes as she approaches the nest. Anyhow I returned to get the chick but its eyes were closed and it was still. This time there was no resurrecting it. I had been worried in case if I put it back in the box and it died it would be unhealthy for the other birds. Anyhow the poor little thing had solved my problem. Very sad but one less mouth to be fed and at the time of writing all the others Pseheomtos |
Dalkey Fox Resting
