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July
   

July


What to look for in July

Orchids

Late flowering orchids such as the pyramidal orchid are still in bloom within the site, mainly in the chalk grassland. Many species of orchids have suffered a great decline in numbers over the last 50 years as the unimproved grassland on which many of them depend has decreased nationally by 97%.

Charles Darwin was fascinated by orchids and how they and their insect pollinators are adapted to each other. Orchids retain their pollen in little 'sacks' called pollinia, which means that less is eaten by insects or blown away by the wind. They are often only pollinated by a particular insect species and therefore dependent on the survival of this insect species for cross fertilisation. When the insect lands on the flower and follows the honey guides in a search for nectar, the pollinia become attached to them. As the plant tissues surrounding the orchid pollen sacks dry, the position of the pollinia on the insect changes, so that when they arrive at the next orchid flower of the same species, the pollinia are in exactly the right position to stick onto its stigma. Much of this was first reported by Charles Darwin whose next project after completing 'The Origin of Species by Natural Selection' involved researching orchids growing in the local area. As a result of this he wrote the book 'On the various contrivances by which British and Foreign Orchids are pollinated by Insects' which can be read by looking at: http://pages.britishlibrary.net/charles.darwin3/
orchids/orchids_fm.htm


Grasses

Many species of grass are flowering this month and some of the butterflies whose caterpillars eat grass can be seen in the meadows drinking nectar from flowers growing amongst wild grasses. Amongst these are large, small and Essex skippers and meadow brown butterflies. Letting some grass grow long in your garden and remain overwinter could help the numbers of brown and skipper butterflies to improve.

When Darwin started trying to identify grasses he had help from Joseph Hooker (a great friend of his and the Director of Kew Gardens) with the more difficult ones and wrote to him in excitement about naming his first grass,

"I have just made out my first Grass, hurah! hurrah! I must confess that Fortune favours the bold, for as luck would have it, it was the easy Anthoxanthum odoratum (sweet vernal grass) : nevertheless it is a great discovery; I never expected to make out a grass in all my life."

Birds

Hobbys were seen within the nominated Site in 2005 and both tawny and little owls were heard calling on the High Elms Estate. Please do let us know of any sightings by filling in the form on the Record your sightings page.

Bats

On summer evenings bats fly along the hedgerows hunting for insects including moths. The most common bats in the site are common and soprano pipistrelles. These are Britain's smallest bats, and were thought until recently, to be the same species. The young will soon be leaving the maternity roosts where they were born and fed by milk from their mothers. When they leave these roosts they will have to fly and learn to catch insects like their parents.

Newts

Most adult newts have left their breeding ponds by the end of July to live on land, hidden in refuges such as log piles. They feed at night, often prefering slow moving minibeasts such as slugs.

Bank Vole

Bank vole numbers increase rapidly at this time of year. They can produce 4-5 litters of 4-6 young every 9 weeks. Many of these are food for predators such as weasels, owls and kestrels.


If you are interested in finding out more about small mammals, a mammal surveying group has been set up. To get in touch and find out when the next survey is to be held please contact: 01689 862815 or e-mail: countrysideandparks@bromley.gov.uk

Glow Worms

The 2 year-old larvae of these segmented beetles reach maturity at this time of year. Having pupated for 8-12 days (female glow worms) 11-15 days (males) they shed the last of their larval skins. The wingless females are twice the size of the males and after dark climb to the top of grasses and turn up the tip of their abdomens to show the underside of the last abdominal segment glowing with a cold, greenish light. The light is formed when luciferin in the female is activated by the catalyst luciferase and it attracts males, which fly to the females, mate and die. Male glow worms only live for about a week, females for 2-3 weeks. The eggs are laid under logs or stones, at the base of grass stems or in moss, and hatch about 35 days later. Within a few hours of hatching, the skin of the larva becomes hard and black. Larvae live on a diet of snails which they inject with a digestive substance and then ingest. Glow worm numbers have decreased greatly and these interesting insects are a Bromley Biodiversity Action Plan Species. Look out for glowworms on summer nights. Please let us know if you see one in the proposed World Heritage Site by filling out the form on the 'Record Your Sightings' page.

Stag Beetles

More common in Charles Darwin's time, these magnificent beetles can be seen flying in July within the site but tend to be more common in areas where the soil is derived from alluvium. They are not generally found in areas of chalky soil where the lesser stag beetle tends to be more common. Both stag beetles and lesser stag beetles mainly lay their eggs in the decaying stumps of deciduous trees especially oak and fruit trees. The larvae eat the decaying wood and live within it for 5-7 years until they are mature. It has been reported in Bromley that holes from which stag beetles have emerged were later used by common newts. Stag beetles are still quite common in Bromley, but in the UK generally their range has greatly declined and they are endangered within Europe.

Stag Beetles are a Bromley and London Biodiversity Action Plan Species. For more information about stag beetles in Bromley go to:
www.bromley.org/ciswebpl/bbap/sapsstag.asp


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