Wednesday, 7 June 2017

Garden Bioblitz 2017

At the weekend it was this year's garden bioblitz. A bioblitz is when you survey an area and identify all the species in it- for gardens, that means anything that wasn't introduced by humans.

The easiest thing to look for are the birds. We get a decent range of birds in the garden but the species seen varies on a day to day basis. Over the 24 hours of the survey I spotted six different species in the garden. The loudest and most obvious birds, as usual, were starlings.

This is a starling that was not happy with my presence in the garden. You can see how it is able to make such a loud screech by having the ability to open it's mouth widely. This aggressive screeching is probably the most common sound you hear from starling but they make a variety of noises and are talented mimics which can copy the sounds of around twenty different species of birds. They've been known to be able to mimic human speech too, like parrots- you can find lots of videos online of starlings doing just that (like this one).

Another of the bird species I saw was a goldfinch

Goldfinches seem to go through periods where they are almost constantly in the garden feeding on the nyjer seeds and other where we hardly ever see them. It's likely at the moment they have young so are busily gathering food for them. They usually nest in areas with scattered trees and shrubs which makes gardens an ideal habitat for them. The nests are likely to be high up in a hedge or evergreen tree and are constructed from mostly grasses and moss interwoven with wool and hair. 

The other birds seen as part of the bioblitz where blackbirds, house sparrows, robins and a feral pigeon/ stock dove. The most interesting part of doing a bioblitz is looking closely in all the nooks and crannies of the garden where you find a large range of invertebrates. I found less species this year, likely because the weather had been warmer and sunnier and most invertebrates prefer damp, cooler places. They are likely still present in the garden but are harder to find. 

It's hard to have a pond in a small garden but we do have a barrel filled with water which birds drink out of. It doesn't really look like an ideal habitat. 

But in the last few week I noticed that the surface of the water was home to water boatmen (Notonecta glauca) (also known as backswimmers). 

I ingeniously used a clear tupperware box placed on a piece of plain paper to get this really clear look at a couple of them. They are actually flying creatures which is no doubt how they found our barrel. They have a really interesting way of staying submerged underwater. Instead of using oxygen dissolved in the water like most aquatic insects, they have an extra oxygen supply from haemoglobin in their abdomen. This comes in the form of bubbles of air which provide buoyancy and change size as they respire.

I lifted all the plant pots and found lots of invertebrates. One was crawling with worms. 

Worms are quite tricky to identify as they all look fairly similar to each other. I suspect though that these are probably common earthworms (Lumbricus terrestris). They mostly feed on plant material but have been observed feeding on everything from dead insects of faeces. 

You can also see there are lots of woodlice there too. In some areas of the garden there were over a hundred woodlice in similar spaces. 

This once is the most common UK species, common rough woodlouse (Porcellio scaber). I also found in small numbers common pill, common shiny and rosy woodlice. Woodlice are actually crustaceans like crabs and lobsters with a similar hard exoskeleton. They shed these as they grow but do so in two halves. Young woodlice are kept in a "marsupium" in the underside of the mother's body. The mother then appears to 'give birth' to tiny woodlice. 

My other find under the flower pots was a single centipede (probably a common centipede). 

Centipedes are fearsome predators which sprint at prey very quickly, pounce on it and inject it with venom. Despite the name centipedes never have one hundred legs as they always have an odd number of pairs. It's hard to be certain but I think this one has 23 pairs of legs.

Whilst looking in the various nook and crannies I found a few spiders. This first one is a fairly common lace web weaver (probably Amaurobius similis). 

Another one, which was harder to photograph as it wouldn't keep still, a jumping spider probably Salticus scenicus.

These spiders don't build webs but instead pounce on their prey (hence the name). They tend to eat smaller spiders and similar insects but have been observed taking on prey three times their own length. They also perform a mating dance- the males wave their front legs and moving their abdomens up and down. 

All in all I identified 31 different species of birds, invertebrates and plants. It's incredible to see just how many species you can find in a small garden. Bear in mind too that this was only done on one day- if I did this more regularly the number would be considerably greater. Doing a bioblitz is a lot of fun and a really rewarding environment. 

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