Dolphin School - Eco Warriors

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Tony Towner is delighting and informing us as he photographs and details the biodiversity at Dolphin School.

During the cold spell early January, I was lucky enough to photograph this Redwing, which is rather an unusual visitor to the Dolphin school grounds.

The Redwing is a winter visitor to this country and migrates from Iceland and Scandinavia. They normally eat fruit and berries in the autumn and winter, but with all the snow and ice around, their usual food source must have been increasingly difficult to find. Hence I found this one turning over leaves like Blackbirds do in the compost area of the orchard, presumably trying to find some invertebrates.

Redwings belong to the Thrush family of birds and are somewhat smaller in comparison to our commonest Thrush, the Blackbird. The main identification features are the whitish stripes above the eye and beneath the cheek, and by the rusty-red flanks when perched or by the rusty-red underwing when in flight.

Now that the snow and ice have retreated, the Redwing has moved on to its more usual food supply.

With the warm weather this autumn there has been much opportunity to study the many species of dragonfly that we are lucky enough to have around the Dolphin pond. The handsome species above shows a male Southern Hawker dragonfly that I found resting and basking in the sun towards the end of September. There are certain identification features that we have to look out for that distinguishes this species from Migrant, Brown and Common Hawkers that are also around the Dolphin pond during September and October.
Brown Hawkers, as the name suggests, are predominately brown and so we can eliminate that species. However, Migrant and Common Hawkers could possibly be confused with Southern Hawkers and therefore it is worth noting these differences. Firstly, there are two broad apple-green vertical stripes between the head and the wings on top of the thorax known as antehumeral stripes. These are narrow or almost absent on the other two species. Secondly, there are paired spots on each segment of the abdomen except for the last two segments (S9-10) which are stripes. The other Hawkers have paired spots on every segment. These markings are apple-green except for the last three segments (S8-10) which are sky blue. The Migrant Hawker is predominately blue on the abdomen and the Common Hawker blue with yellow flecks.
The behaviour of this species is also quite interesting and helps in identification. Males will closely investigate human intruders that are in their territories, hovering about waist height just in front of them before returning to their regular beat.

I have been lucky enough to discover a small colony of Purple Hairstreak butterflies in the Ash trees at the far left hand corner of the field. This is a very difficult species to find and observe as they spend most of their life up in the tree canopy. Unlike most of our native butterflies, this species shows little interest in the nectar of flowers and instead feeds on the sugar-rich honeydew deposited by aphids on oak, ash and aspen leaves. The photograph shows the butterflies proboscis inserted into the leaf of the ash tree.

Identification of the male is by a purple sheen with dark borders on the upperside compared to just a flash of purple on the forewing of the female. The underside of both sexes is similar, with prominent white lines on a greyish background, and orange-yellow spots near the corner of the hindwing.

The Purple Hairstreak has one generation a year and flies from late June until early September. They are reliant solely on the oak tree to complete its life cycle. The eggs are laid singly at the base of an oak leaf-bud and the small caterpillar remains inside the egg until the following spring. During March the young caterpillars emerge and start to feed within the leaf-bud. After six weeks they change into a plump brown chrysalis which is formed on the ground and is capable of making a rasping squeak to attract the attention of ants. Protection from attack by parasitoids and other small predators is gained from the ants, in return for a sugary meal exuded from a gland on the back of the chrysalis. The ants usually cover it to hide it, or transport it into their nests at the base of oak trees.

On the 16th June, there was great excitement when a group of Year One girls found this small Grass Snake under one of the turfs by the tennis court fence. As the snake was getting agitated by all the sudden attention it was getting, I transferred it into the meadow area of the pond. There have been several sightings of adult grass snakes swimming in the pond and I have also seen one coiled up basking in the sun on the rubber mats leading up to the caretakers shed.

The Grass Snake is the longest of our three British snakes and can clearly be identified by the light yellow/cream collar just behind the head, as shown above. Grass snakes feed on tadpoles, frogs and toads, as well as fish, newts, and occasionally mice and small birds. Most hunting is done underwater, and prey is typically swallowed alive. They are good swimmers and do so with their heads out of the water, but if disturbed, will dive underneath and hide amongst water weeds where they can remain for up to an hour

Grass snakes mate in April-May. The female lays 8-40 eggs, depending on her size, in July-August in a warm site such as a compost heap or under rotting logs. The young snakes have an egg tooth to help them hatch out of the leathery eggs in late August-September.

They are active during the day and spend time basking in the sun to warm up. They hibernate from October to March, often communally in old rabbit burrows, wall crevices and under tree roots.

You may recall that I was trying to trace the source of the food that the Blue Tits were feeding to their young.

I found this caterpillar on my rucksack after standing under one of the many Oak trees situated around the school, and I believed this could be the source of food. I took it home and on that same day it started to spin a cocoon. I placed it in my rearing tent and after 3 weeks it changed into the moth below, a Ptycholoma Lecheana. There must be hundreds and thousands of these caterpillars around the school as it takes approximately 15,000 caterpillars to raise a brood of Blue Tits.

I put this nest box up earlier in the year on a tree in the pond area, and luckily a pair of Blue Tits took up residence. If you watch carefully, the adults are feeding their young every couple of minutes with tiny green moth caterpillars. I’m currently trying to trace the source of the food as I would like to know what species of Moth these caterpillars belong to.

The female lays 7-13 eggs in April-May, which she incubates for about 15 days. During this period, the male defends the area around the nest site from other Blue Tits, so protecting the available food needed for both adults and, later, the young. This is probably the reason that our camera nest box by Meadow building reception is not being used. Next year, funds permitting, I would like to try the camera nest box on this particular tree.

The chicks will then fledge after 19 days.

Look out for this male Mallard on his favourite tree stump in the pond area. He tends to be there first thing in the morning, but as he does not like too much disturbance, he usually disappears around mid morning break. Sometimes he brings a female with him, and I will try and photograph her at some other time to show the differences.

The main identification features are the metallic green head, narrow white neck collar, purple-brown breast and grey back.

The Mallard is classed as a surface feeder or dabbling duck rather than a diving duck. As it does not dive, the legs are positioned near their centre of gravity in the mid-body. This helps them to ‘spring’ from the surface of the water when flying off. Diving ducks have their legs positioned further towards their tail end, which means they usually need a run up to get airborne.

During the sunny weather last week there were many of these Damselflies feeding in patches of sunlight around the pond area and the shrub borders outside the Basilica. This species is the first one to emerge in spring and is known as the Large Red Damselfly.

The other red species to be found in Britain is the Small Red Damselfly, but unless you have the two side by side, it is not always easy to distinguish by size alone. The easy way is to check the colour of the legs. The Large Red has black legs as shown above, and the Small Red has reddish legs. Also, the Small Red does not emerge until late May and is normally found in boggy heathlands.

This moth was photographed on Wednesday 18th March after Tony found it attracted to a lighted window in Meadow building reception. The species is the Oak Beauty, which is common and well distributed in south-east England . As the name suggests, the caterpillars feed on oak trees as well as other deciduous trees. The flight season is late February-April.

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