WILDLIFE REPORT JULY - SEPTEMBER TOP PAINTED LADY Vanessa cardui BOTTOM COMMON BLUE Polyommatus icarus

Transcription

1 WILDLIFE REPORT JULY - SEPTEMBER 2015 TOP PAINTED LADY Vanessa cardui BOTTOM COMMON BLUE Polyommatus icarus

2 Introduction High summer belongs to insects and this year they have not disappointed, after what seemed an indifferent start to the summer there have been new sightings and overall increases in butterfly populations. Two of the larger British moths have also been spotted on the nursery and this has provided the impetus to embark on a proper analysis of our moth population. Plenty of other insects have been around as well! Moths The night flying equivalent to butterflies doesn t usually get a separate mention in this report but they have been pushing for more recognition by being more obvious than in previous years. Up to and including this summer, records have been entirely of moths spotted at rest during the day or those disturbed accidently. This includes these two which are among the UK s biggest moths. Neither is particularly rare but they are not often encountered and they are very impressive insects. Pictures of both these moths were forwarded to the Sussex Moth Group for verification and addition to the Sussex moth data set. Left Oak Eggar moth resting in the grass near house A-D. Right Pine Hawk moth on the office window frame. It is because we have been seeing these moths that starting in September we have been using a light trap to sample which moths are about and how many in a more systematic manner. Light trapping is an effective method of sampling as most moths are attracted to light. The trap is left lit overnight and in the morning the catch can be counted and then the moths released unharmed back into the environment. The data for the first catch is shown in the panel on the left. They are six pretty ordinary species of moth but importantly a start has been made and some experience gained. The next time the trap is used we will deploy a longer extension lead so that the trap is further from any buildings and the light visible over a greater distance. In a better position we hope to catch more moths through the last months of Then next year we should be able to survey consistently and get a set of data covering a whole year. wing) and on the right a Setaceous Hebrew Character. The three moths above are typical of the first insects caught in the light trap. On the left is an Angle Shades, in the centre a Small Emerald (which has lost a piece of Butterflies

3 This years survey is now complete, the data collected is on the chart below. There is now consistent data collected in the same way for three years and it is now possible to draw some conclusions about how successful we are in improving the butterfly populations. A new butterfly species

4 But first mention goes to the discovery of the Brown Argus butterfly on the site, in the area east of the rainwater reservoir. This little butterfly is similar to a female common blue and can easily be mistaken for it. It is therefore quite possible that this species has been counted as Common Blue until this summer. Close examination of the underside of the wing is diagnostic as there are less spots than a Common Blue. Now that we know both species are here we will be aware of the need to check closely! This addition means that 22 species out of the 59 species that are resident or regular migrants to Britain have been seen on our nursery. Butterfly survey Data for three years is not enough to be making very detailed assessments as insect populations can fluctuate hugely from year to year, but there are two overall statistics that look significant. The best butterfly count on a single survey in 2015 is 326 insects that is a 21% improvement on the 269 in 2014 and 2013 was less again at only 245 insects seen. The total number of butterflies counted in 2015 was 1126, about 40% more than the previous two years which had similar totals (784 and 803). Both of these statistics point to an improvement in the butterfly population over the nursery. The business has endeavoured to increase the area suitable for butterflies and these statistics suggest that the butterflies approve of our changes. The key to getting more insects is making whole areas more suitable as butterfly habitat. The populations will always be very limited if only peripheral land and margins are made available. The population can grow more if there is habitat away from the margins. This is illustrated well by the influx of butterflies onto the field beside glasshouse There are since we only mowed a loop around it a lot more butterflies than previously. Now they see the whole field as a place to live just the perimeter. For example, on a damp day in August a slow walk around this field revealed a dozen or more Common Blue butterflies roosting on grass stalks waiting for the weather to improve; this would not happen with short mown grass. Likewise the mating pair of Meadow Brown butterflies (pictured left) has this field as their home. They would not be here except for the new regime. The pictures on the cover The start of this report is of two pictures of butterflies because both these species have had a good year in Painted Lady, a migrant species has been recorded nine times during a butterfly survey this year; its first year on the survey, thus adding to our surveyed species total. It is also the subject of an ongoing study and sightings can be posted to Butterfly Conservation to add to their data base and this has been completed. The Common Blue has had a good year, 24% more individuals than last year. We began with no Common Blues seen in 2012, to just four in 2013, then 37 in 2014 and now 46 in This looks like significant progress for this butterfly. Common Blue is a fairly sedentary species; most individuals will not fly very far so these 46 can be thought of as our population and they are doing better than before on our nursery. This also points towards butterflies gaining from our management of our environment. Birds There is a new species to add to the nursery list in this quarter. A Common Sandpiper was seen beside our rainwater reservoir in September. This bird was probably on passage and stopped for a while before moving on again. This addition to the list takes our species total on to 51 since Amongst our more regular species three special events stand out. On our fat ball feeder we had four Great Spotted Woodpeckers feeding together. This was only seen once and we think that most, if not all the birds were fledglings from a nest nearby, probably one just across the road from the feeding station. We think that the birds had fledged very recently, perhaps that day and were bought to the feeding station by a parent bird. Since that occasion we have seen the woodpeckers several times but never more than two at any one time.

5 Secondly our swallows raised two more broods in the old pack house, so there were a total of three successful nests this summer and total of twelve swallows fledged. To give the birds access to the building when the main doors are closed there is a small pane of glass removed, just under the guttering. This is about 40cm 2, quite a large opening. This pane, which is left deliberately missing, is our main intervention to help the swallows to be successful. It appears that this is much bigger than required as there is also a broken pane that has created an opening only 30cm wide and with a maximum depth of 5cm. The adult birds have been observed using this tiny gap with no difficulty at all, quite an aerobatic feat and probably beyond the capability of the fledglings. The third notable observation was of a Kestrel, which is a bird seen quite often. It was interesting for its behaviour. It was sitting on glasshouse studying the grassy area north of the glasshouse. We think the bird had taken up this position so it could see if any suitable prey made a dash across the mown loop in the field. If this is correct this is new habitat for hunting over because in previous years this was all short grass which small rodents would have avoided. The chart below shows the updated species list for the nursery. Wild Flowers Ox eye daisy Last summer there was at least one ox eye daisy plant flowering in the field beside glasshouse A-D. It was not noticed this summer even though it is a perennial plant and should be there somewhere. Possibly it had got nibbled too frequently to flower by rabbits. This flower is well liked by a whole range of pollinating insects so it was disappointing not to find it this year. We have though found large clump growing on the side of the original reservoir in the centre of the nursery. In this position it is never going to flower as we like to keep the reservoir bund well cut. So instead we have dug up this plant and split it into 14 pieces. They are now growing on in pots in preparation

6 to plant them in appropriate places during the autumn where they can flower, hopefully spread and provide more resources for pollinating insects. Other flowers There are no new species to record in this period but the improvements in butterfly numbers are at least in part because of increasing availability of suitable flowers. Of particular importance in this regard are the two flowers being chosen by the butterfly species in these two pictures. The purple flower is knapweed and there are many more this year than last, particularly a colony in the corner of the field beside glasshouse The other is fleabane, which is widely distributed across the site and a favourite with pollinating insects. Knapweed and fleabane flowers chosen as a nectar source by Small Skipper butterflies. Dragonflies and Damselflies Every year some dragonflies are seen on the nursery. This year we have seen two species for the first time. It therefore seemed appropriate to give this group of insects a separate mention in this report. Dragonflies Over the last four years six species of dragonfly have been seen flying here and all of them have been seen here this year. The table below lists all of these species. Of these the Southern Hawker and Emperor Dragonfly have appeared for the first time this year. SOUTHERN HAWKER EMPEROR DRAGONFLY MIGRANT HAWKER BROAD BODIED CHASER BLACK TAILED SKIMMER COMMON DARTER Aeshna cyanea Anax imperator Aeshna mixta Libellula depressa Orthetrum cancellatum Sympetrum striolatum Common Darter perching on a fence All these large insects are strong fliers and have a strong instinct for dispersal or migration after emerging from the larval stage. It is during this dispersal period that they can be found away from water. Here they can reach maturity before moving to an aquatic environment in order to take and hold a territory and find a mate. It is in this part of their lives that a good place to live can be any warm and sheltered place with abundant small insect prey. The small parcels of land surrounded by high trees, buildings or hedges that exist all round our nursery provide an environment that is wind free and warms up quickly in the sun. Broad Bodied Chaser in the field beyond the rainwater reservoir. Picture by Andy Faulkner

7 The most commonly seen of the dragonflies are the Migrant Hawker and Common Darter; they are about continuously through late summer and autumn. Black Tailed Skimmer and Broad bodied Chaser are seen in early summer most years but only occasionally. LEFT Migrant Hawker RIGHT Southern Hawker These insects are big and are powerful fliers and will on occasions investigate people but they are no threat to humans they cannot sting and their bite is reserved for their insect prey which is usually a very small insect. Damselflies The other half of this group of insects is the rather dainty damselflies. Four species have been seen on the site mostly near to the rainwater reservoir. The species are listed in this table. Emerald Damselfly Azure Damselfly Common Blue Damselfly Blue-tailed Damselfly Lestes sponsa Coenagrion puella Enallagma cyathigerum Ishnura elegans The place to look for these little insects is in amongst the long grass, where the air is warmer and almost still. Along the bank of the rainwater reservoir is a good place as is the long grass we have left this year in the field beside glasshouse Sometimes there can be dozens of them flying about. The rainwater reservoir is one of the places where they are breeding and they can seen laying eggs there.

8 Living under the Radar Sharing our nursery with the insects that are easily seen is a host of other mini beasts. We are not attempting to meet their exact habitat requirements. It is just necessary to leave that space where can nature do its thing. It is in these less manicured places where they are most successful. Here are three of these mini beasts making good use of lush summer growth to find a place to live. The red beetles are Soldier Beetle on some Yarrow flowers. The black beetle is the Golden Bloomed Grey Longhorn, it is living behind glasshouse 6-9 and likes the Hogweed which grows there. The cricket is Roesel s Bush Cricket; and they are plentiful around glasshouse A-D. Summary Summer is now coming to a close and the season when the insects take centre stage is finishing. Their time in the spotlight is over and they have performed well. A new species of butterfly this year and the biggest population counts ever recorded. Our bee hotels have had their first guests both mason and leaf cutter bees. Other sorts of insects have added to the variety as well. It s been very good summer for insects and better than previous years. The next challenge is autumn, the season to make the preparations to get 2016 to be as good as this summer.

9 Interaction board Two new panels have been prepared for the board. Both these panels incorporate the company logo for the first time. One is a resume of the butterfly survey for the previous three months the other is about the moth we caught in the light trap on the 4 th of October which will be reported on in the next report. Two older panels will be retired to make space for the new ones.

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