It is that time of year when the majority of breeding birds on the reserve are busy hunting for food to feed their newly hatched chicks. As with all wildlife there is a food chain, with the big predators at the top and the unfortunate smaller species at the bottom. Over the moorlands it is the Hen Harrier and Merlin that sit at the top of the chain with their usual preference of prey being Meadow Pipit, Skylark and any other small bird that crosses their path. Hen Harriers also go for Voles and other small mammals.
Hunting male Hen Harrier catching small mammal (Video by Gavin Chambers with mobile through scope)
So for Hen Harriers and Merlin to have a chance of raising a brood they need access to a good supply of Meadow Pipit and Skylark which Lake Vyrnwy certainly has an abundance of and are monitored to make sure they are not dramatically declining. Meadow Pipit and Skylark generally feed on small caterpillars, craneflies and any other insects they can catch.
Meadow Pipit (Left) & Vole (Right) (Photos by Gavin Chambers)
Insects are also very important to the success of breeding woodland birds. Birds need to try and time their egg laying, and therefore hatching, to coincide with the availability of suitable food. For newly hatched chicks small caterpillars are the best choice of food and once larger the chicks can take numerous other insects. This years prolonged cold spring/early summer, certainly here at Lake Vyrnwy, would appear to have slowed the emergence of caterpillars and given the early breeders such as Blue & Great Tit a hard time. A number of nest boxes have been found with dead broods which is likely to be due to starvation. However Sparrowhawk and Goshawk could be to blame as they could have taken the adult birds to feed their own young.
Nuthatch carrying Mayflies for chicks near Centenary Hide (Photo by Gavin Chambers)
It is by no means all doom and gloom, early indications are that box occupancy is high and it is a good year for Pied Flycatcher breeding attempts. Pied Flycatcher eggs have only just started to hatch in the last few days so hopefully there now will be plenty of caterpillars available. With the forecasted heatwave for the end of the week we have our fingers crossed chicks will survive till then when many more insects should become available.
Female Emperor Moth (Left) & Drinker moth caterpillar (Right) (Photos by Gavin Chambers)
The rise in temperature will hopefully bring an increase in butterfly and moth numbers. Green Hairstreaks have been frequently seen in sunny spells recently and the first Small Heath of the year has been spotted. On the moors Emperor moths have been zipping about, usually males during the day, and hairy caterpillars of the Drinker moth munching on grasses. The large Emperor moths are a prey item of the Hobby, as will the Northern Eggar moths later in the year. Hairy caterpillars are a favourite of Cuckoos who, unlike other birds, have the ability to eat them despite being partly poisonous. Nightjars also like to catch adult moths, we had our first churring bird on the 24th May.
Plant of the Week – by Gethin
Marsh Violet / Fioled y Gors (Viola palustris) (Photo by Gethin Elias)
Also known as Bog Violet, it is a low growing plant with creeping underground rhizome. It has blunt, kidney-shaped leaves and a small pale violet blue flower with darker veins and with a blunt pale lilac spur.
It has a split distribution, being widespread in the northern half of Britain and in Wales, but uncommon in the east of England and in some parts of central Britain.
This is also the food plant of the Small Pearl-bordered Fritillary caterpillars. One of our many declining butterflies which will hopefully be on the wing in the next few weeks.
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