February 2014 – Grantham Ecology

Tree bumblebees in Grantham

February 27, 2014Grantham EcologyLeave a comment

Bumblebees are fascinating insects and I have been meaning to learn more about them for a long time. I’m not sure that it doesn’t have something to do with the fact that they looks quite so similar to colourful bats up close… there is something about their furry round bodies which is rather reminiscent!

It is still very early in the season but most of our UK species respond to conditions rather than dates and when the sun is shining and the weather is mild, many hibernating species will come out of torpor and begin their spring routines. I have recorded pipistrelle bats in flight over the last week; the birds are certainly thinking about nesting with the early species such as long-tailed tits gathering nesting materials; and there was quite a gathering of bees on a very early flowering blackthorn on Monday lunchtime.

I managed to get a couple of photographs of this bumblebee and decided that this would be the first ID on my path to learning more about these species. And it looks as though I picked quite a good one – my tentative ID of a tree bumblebee (Bombus hypnorum) was confirmed by helpful tweeters @sbd08simon and @ed_p_wildlife. Apparently there is no other bee which this species can easily be confused with – the colouration is just black and buff-brown with a white tail. No coloured bands! This bee has quite a simple pattern compared with the multitude of variations which other species seem to manage! This guide from Bumblebee Conservation gives a great introduction to identifying bumblebees.

Although I am, as already confessed, no expert, I believe this must be a queen out foraging and potentially searching for a nesting site. The queens emerge in spring (usually March or April) and scope out potential nesting sites before laying their eggs. About six weeks later, the eggs hatch and the entirely female workforce splits into teams, some foraging for the colony, others staying in the nest to do the housework. Later in the year, ‘reproductives’ are produced – these are virgin queens and/or drones. The drones will die after mating with a female but the queens will hibernate through the winter and emerge when the temperatures warm up in the spring and the cycle can begin again. I would therefore suppose that my bumblebee feeding in February is a queen freshly emerged from a relatively short winter’s sleep.

Tree bumblebees are so called because of their habit of nesting in trees – either in woodpecker holes or more frequently, in nest boxes. Like most species, they have adapted to inhabit the world we have created around them and can also be found nesting in houses, in soffit boxes and similar features. Some other species of bumblebee will occupy similar niches but the preference for these tree (or tree-like) nesting sites is most notable in the tree bumblebee. Many other UK species will nest underground and you can often see them bumbling into the undergrowth towards the entrances to their underground homes.

Tree bumblebees are a relatively new additional to the UK’s fauna – they first appeared in Wiltshire in 2001 and have been spreading north every since. It is believed that they are natural colonisers which have established under their own steam, much like the collared dove which was a rare vagrant until the 1950’s when they were first recorded breeding here and now grace most garden bird tables across the UK. The invasion of the tree bumblebee appears, so far, to be benign with no observed impacts upon existing native bee populations and its spread appears to be continuing with the first recording in Scotland last year.

I have recorded my sighting here – the data gathered from recordings around the country can be used to study this species and describe its distribution around the country.

If you want to read more about the tree bumblebee, there is a very informative factsheet available from Bumblebee Conservation.

Making a home for the birds and the… bees!

February 25, 2014February 25, 2014Grantham Ecology4 Comments

National Nestbox Week is designed to encourage people to provide more homes for wildlife in their gardens – why stop with the birds? I spent last Sunday making bird boxes, bat boxes and this – a home for solitary bees.

I confess to knowing very little about these bees but I do find them fascinating – I watched one coming and going from an old drill-hole in a fence post in the garden last summer and meant then to do something to increase the availability of suitable niches for them this year.

February is the ideal time to install these habitat features – it gives them time to naturalise a bit as well as ensure that they are in evidence for any bees which may be seeking a home as the temperatures rise in the spring.

You may well have seen various bee houses for sale in garden centres and similar gift shops. I have always been surprised at quite how much these cost, although drilling all of the holes made me re-consider the economy of having somebody else do it for me! Nontheless, I rescued a selection of silver birch logs from my parents’ house (they recently took down a tree and the logs seemed too beautiful to be consigned to the ashes of the logburner) and set about making a mini bee hotel.

The logs were cut into 7 inch sections and I made a simple frame from some old offcuts of wood to hold them. I would suggest, if you choose this approach, to screw the frame together very firmly. This allows you to pack the logs in tight and hammer in additional smaller pieces to fill in the gaps and keep them in place, using the tension of the solid frame to hold against.

Once I had arranged the logs in a fairly stable manner within the frame, I set to work drilling holes in the logs, being careful to remove as much of the sawdust as possible and making sure that they were pointing slightly upwards to stop the rain from getting in.

This guide provides an excellent introduction to making these habitats and, following its recommendations, I have made holes from 2mm to 8mm in order to attract a range of different types of solitary bee.

I could not find much in the way of siting recommendations for these habitats although one page on the Telegraph website suggested the sunniest spot in the garden. Our garden is quite shaded but I have selected a spot near the vegetable and herb garden, to encourage pollinators to our vegetables this year, where the sun shines throughout the morning and should provide warm conditions. It also benefits from being sheltered to prevent rain from reaching the bee hotel.

Below are some step-by-step photographs showing the creation of the feature – I will hopefully update in the summer to describe all of the bees which have come to use it!

If you wanted to encourage bees in a more casual way, the guide recommends simply drilling holes into fence posts and other logs and pieces of wood around the garden. This creates less of a feature but, in terms of encouraging biodiversity into your garden, it is ideal!

Silver birch logs which looked too beautiful to burn!

Cut the logs into 7in sections which can then be drilled longways to create the holes for use by solitary bees.

The logs stacked inside a simple wooden frame made from offcuts of wood. It took a while to arrange them all in a stable manner but a sturdy frame allows you to hammer in additional smaller pieces to pack the logs in, using the tension of the frame to hold them in place.

Then drill! This is the finished product, filled with various sized holes from 2mm up to 8mm. I would suggest drilling all holes with a small drill bit to begin with, then widen some of them to different sizes as starting work with an 8mm bit is tough going! The metal around the outside is not part of the design, rather the shelving unit behind a shed where pots are kept - it faces onto the vegetable and herb beds whilst the shef above it also provides cover from the rain. — Then drill! This is the finished product, filled with various sized holes from 2mm up to 8mm. I would suggest drilling all holes with a small drill bit to begin with, then widen some of them to different sizes as starting work with an 8mm bit is tough going! The metal around the outside is not part of the design, rather the shelving unit behind a shed where pots are kept – it faces onto the vegetable and herb beds whilst the shef above it also provides cover from the rain.

Don’t forget the bats in National Nestbox Week!

February 22, 2014February 22, 2014Grantham EcologyLeave a comment

This week is National Nestbox Week which encourages people to put up nest boxes in their gardens. This is a great idea and focuses attention on providing these features as the birds first start to pair up and scope out nest sites. We have birds nesting in various locations around the garden but, for some reason, I had never got around to adding some more purpose built nesting habitats for them – something I have now rectified!

But why stop at providing habitat for garden birds? Don’t forget that gardens are vital to some of our most common bat species, such as the common pipistrelle and the brown long-eared. Attract bats to your garden and you will be able to watch fantastic aerial displays as the sun goes down throughout the summer. There are lots of tips from the BCT on how to attract bats to your garden.

There are many designs of bat box on the market and plenty of designs which you can make for yourself. I realised that the offcuts of wood we had in the shed provided everything I needed to make a Kent Bat Box – one of the simplest designs and one I would strongly recommend to anybody putting one together for the first time. This box is very simple and creates cavities which small bats such as common pipistrelle can use as a roost. This video shows the kind of tight niches which are used by pipistrelle bats.

Bats fly in the garden regularly throughout the summer and one of them – probably a brown long-eared – uses the porch as a feeding perch. I know this from the little piles of moth wings which suddenly appear some mornings, often 5-10 of them. The bats bite off the wings of the moths they have captured, eating only the nutritious bodies of the moths and leaving the wings to flutter down. Just opposite the porch is a holly tree and this struck me as the ideal place to put a box, seeing as I know the bats use this little niche of the house and garden.

Moth wings in the porch - they have caught on the spider's web on their way down but there are tell-tale signs that a bat is responsible - especially as so many appear overnight in a single night! — Moth wings in the porch – they have caught on the spider’s web on their way down but there are tell-tale signs that a bat is responsible – especially as so many appear overnight in a single night!

I also put up another box on the tree beside it, facing the opposite direction. We were recently called out to climb a tree to check a bat box where the tree was to be removed. The bat box had only been up for a few months and was clearly un-used so we were able to inspect it and take it down without causing disturbance to any bats. There was nowhere else on the site to place the box so I have put it up in the garden instead – I am interested to see if either of the boxes are used and whether a particular design might be preferred.

If you are putting up a bat box, make sure it is high above the ground (at least 4m if possible) to deter predators and ensure that there is not too much disturbance to the bats as you use the garden. Another important point is to ensure that there is a good fly-in and fly-out route for the bats. This can be achieved by imagining the bats dropping from the entrance in an arc which is 1-2m out and 2-3m down. If you have left this space for them, they should be able to enter and exit the box. Another important point is to allow them to emerge into some cover, if possible, or out along a hedge or tree line. Bats use these vegetative features for commuting around the landscape and placing your box in such a location should increase the chances of a bat moving in.

The designs for the Kent Bat Box can be found here and all you need is a plank of wood, some smaller wood for battons, a saw and a drill (or hammer and nails). The design is very simple to follow but below shows the step-by-step progress of the construction.

The log shed with offcuts we've been given for the log burner - but there is a Bat Box there just waiting to be built! — The log shed with offcuts we’ve been given for the log burner – but there is a Bat Box there just waiting to be built!

The constituant parts of the Kent Bat Box, cut to size. At the bottom you can see the three boards of varying lengths, at the top right is the top for the box, top left are the battons used to create the cavities.

This shows how the main pieces fit together - the battons are attached to the long-sides of the boards which are going to be placed one on top of the other onto the longest back-board. — This shows how the main pieces fit together – the battons are attached to the long-sides of the boards which are going to be placed one on top of the other onto the longest back-board.

The pieces constructed in the last image are placed, one on top of the other, with the smallest at the top and the largest (the backboard) at the bottom to create the two cavities which will form the roosting sites for the bats. These are drilled securely together.

Attach the top. As with all bat boxes, the crevices will be downwards facing as bats will land and climb up int the crevices to roost. The top will keep the cavities dry.

A view from the base of the Kent Bat Box showing the crevices which will for the roosting opportunities for the bats.

The chosen location for the bat box - after a bit of 'gardening' to clear leaves and twigs away from the fly-in to the box. — The chosen location for the bat box – after a bit of ‘gardening’ to clear leaves and twigs away from the fly-in to the box.

The new bat box securely attached using a bungee cord to ensure that the fixing does not damage the tree as it grows. The box is about 4m off the ground with a clear fly-in below, opening onto further shrubs and cover for the bats.

National Nestbox Week – Making a Wren/Robin Box

February 20, 2014Grantham Ecology1 Comment

Last Sunday was such a sunny, beautiful day that it called for outdoor projects to keep me busy in the fresh air. The first thing I noticed when I stepped outside was the sheer volume of bird song, with blue tits, robins, dunnocks and wrens all busy singing and chasing one another in pairs around the garden. I even spotted a long-tailed tit clinging to the side of the house, plucking spiders webs from between the brickwork to build a nest. It seemed a little too early to do much in the way of gardening, but the birds were making it clear that they were making ready to nest. What better project than to build a couple of bird boxes! It is not pure coincidence that this week is National Nestbox Week.

I have to say my choice of design was limited by the tools available – I don’t have a drill bit which can make the large round holes preferred by some species such as blue tits, but fortunately the designs for wrens and robins are open fronted which means that with little more than a plank of wood, a saw and a drill (and an old inner tube for the hinge), you can make a nest box.

I actually used plans I found on the Which? website, adapted a little to suit the wood I had available. I’ve sited the wren box within an area of dense shrubs in the garden – this is the habitat favoured by the species and provides them some cover and protection from predators. I attached the box securely (imagine how bad you would feel if the box blew down when the birds had begun nesting!) using a bungee cord as this will not cause any damage to the tree as it continues to grow. The cord may need to be replaced after a few years but should certainly ensure the box is securely attached until it wears down.

The box has been up for two days and already there has been a great tit investigating. I am hoping that it won’t be long before something takes up residence – watch this space! Just for the avoidance of doubt – it’s the camera which is wonky in the video below rather than the nest box!

Below are some step-by-step photographs which show the progression of the box from planks of wood through to completion.

Why not have a go at making a nest box yourself and see what birds you can attract to breed in your garden as part of National Nestbox Week? Construction is not one of my strengths but you will be amazed at how simple and satisfying it is to make a box of your own. All of the instructions to get involved in National Nestbox Week can be found here, along with some great resources on how to build/buy and site your box. Lincolnshire Wildife Trust also have some fantastic resources for building all kinds of bird boxes including those designed for more unusual species such as kestrel. You can register your box with the National Nest Box scheme and then provide updates on the species which use the box and how they fare – all of this information provides valuable data for monitoring and research into garden birds.