Blackthorn – 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.

Spring flowers

March 9, 2012Grantham EcologyLeave a comment

Spring flowers are beginning to appear everywhere! The weather has turned colder now again but spring is still certainly on the way – here are just a few of the species to be seen around Grantham at the moment, there will be many more to come!

Blackthorn (Prunus spinosa)
This is a typical component of hedgerows throughout the country and there are plenty of examples of it aroung Grantham. Most of them are not yet in flower but this specimen growing on its own beside the river seems to be at the head of the pack! Start looking out for the white patches in the hedgerows around now – blackthorn comes into flower before its leaves unfurl which makes for a beautiful spring sight with a mass of creamy white blooms.

You may know blackthorn as sloe – the small purple plum-like fruits which can be used to make sloe gin, jam and, well, little else. These are generally harvested after the first frost of autumn so it will be a long time before these flowers produce ripe fruits.

Flowering cherry (Prunus spp.)
This is another non-native but very welcome spring flower. There are two native species of cherry tree – wild and bird – but the majority of those you are likely to see around are ornamental varieties. This one is growing on Sandon Road, outside of the construction college but you can see them flowering in gardens and public spaced throughout Grantham, including the town centre.

You might notice how similar the cherry and the blackthorn flowers are – they are in fact in the same genus, the prunus. This genus includes all of the cherries including familiar fruits – cherry of course, apricot, peach and plum, as well as almonds which are effectively the stone you might be familiar with and not, therefore, a true nut.

Cherry blossom viewing is one of the highlights of the year in Japan – they have blossom viewing parties and events and there are even forcasts which predict when the blossom will be in its fullest glory around the country, depending upon geographic location and weather conditions. I’m not aware that this has caught on to the same extant here in Grantham, but the flurry of whites and pinks certainly do cheer up the town as you walk through.

Snowdrop (Galanthus nivalis)
One of the most widely recognised spring flowers, these are generally considered to be a naturalised rather than a native species. They are found as natives across Europe and certainly fend for themselves in this country but the first recorded colonies were in the 1770’s *. It is possible that some plants are native however, especially in the south of England, however these on the bank of Grantham College are almost certainly planted. One of the earliest spring flowers, they are probably coming to an end now as the weather begins to warm.

You do get many cultivars and ornamental varieties too – if you want to see a nice display, Easton Walled Gardens, just along the A1 south of Grantham, has a snowdrop week once a year, however you’ll have to wait until next year for the next one!

Lesser celendine (Ranunculus ficaria)
This is a small native species in the same family as the buttercup – the Ranunculus family. The small yellow flowers are another characteristic of early spring and grow in abundance due to their habit of spreading by rhizomes as well as seed. They are most apparent on warm sunny days such as this as they are only open during daylight and close up when it is dark or overcast.

They can be found in many places – they are often present in woodlands or along the bases of hedges where they can spread out into adjacent grasslands. They bloom early in the year, preceding the trees coming into leaf – when they grow beneath a wooded canopy, spring is the time when they will get the maximum amount of light. The plant will die back in May and then remain dormant for much of the remainder of the year.

These flowers were growing alongside the snowdrops on the bank of the college on Stonebridge Road.

As an extra bonus, which I didn’t even notice until uploading this picture, is a tiny little ivy-leaved speedwell (Veronica hederifolia) growing within the celendine patch – see closeup below! You can see where it derives its name from too and, in this case, the latin is a very good reflection of the English. Hedera is the ivy family and folia derives from the latin for leaf; hence ivy-leaved. Veronica is the family name of the speedwells.. This species generally flowers in April – May but it must have found particuarly favourable conditions settled in amongst the celendines.

Winter Buds ID Part 1 – Londonthorpe Woods

January 26, 2012Grantham Ecology1 Comment

Tree identification in the winter isn’t so difficult as you might think! Broadleaf trees lose their leaves in the autumn and develop buds which remain throughout the winter and these make it very easy to work out which species is which. The Woodland Trust have produced a very handy guide to some of the most common species which shows photographs side-by-side for comparison. If you want to identify them in a little more detail, this little booklet is invaluable and provides a few more diagnostic characteristics such as the architecture and bark types. It even has a handy key which takes you step by step towards the correct identification!

Of course, one drawback of relying on the buds to identify the tree is getting to the buds in the first place, which can be a long way off the ground depending upon the tree in question. So Londonthorpe Woods seemed like an ideal place to begin.

Londonthorpe Woods is located just off Londonthorpe Lane as you leave Grantham to the north-east. The wood was created by the Woodland Trust who planted thousands of trees on the 56ha arable site between 1993-1995. The Woodland Trust continue to own and manage the site.

As the site is so large, I concentrated on the first area you arrive at if you step through the gate from the car park. This area has been planted with a number of our native species which will one day develop into a woodland much more natural in character than it may appear at present. Alder (Alnus glutinosa) and willow (Salix spp.) will grow quickly but remain smaller, as will the silver birch (Betula pendula) and cherry (Prunus spp.). The English oak (Quercus robur) on the other hand will grow slowly and steadily to rise to prominance above the canopy one day, with ash (Fraxinus excelsior) close behind. Finally there are hazel (Corylus avellana), hawthorn (Crataegus monogyna) and blackthorn (Prunus spinosa) shrubs which will form an understorey, along with dog rose (Rosa canina).

Londonthorpe Woods Map — Map of the plantation behind the main carpark of Londonthorpe Woods (courtesy of Google Maps).

Each of the species is described briefly below, along with a photograph of the buds to show you what to look for! Click on any of the photos for a larger image.

Alder

Alder buds are red and vaguely conical and remain quite close (appressed) to the stem. They are alternate – each bud is present as an individual rather than a pair and they alternate as you look along the twig, one to the left, then one to the right.

Alder is one of the more helpful tree species in that it often provides extra clues in the winter – the cones are generally present right through until spring time.

Willow

Willow’s are a variable bunch and as well as having several species native to the UK, they hybridise so there is even greater variety than you might expect. I think that this example might be goat willow (Salix caprea) – it will be easy to check when the buds break – goat willow produce fantastic flowers so watch this space! The buds are alternate again, lime green with redness towards the tip.

The presence of both the willow and the alder in this plantation suggests that the ground may be damp – both species are most commonly found along river banks or in other damp conditions. Like the hazel (see below for more details), the willows have been coppiced in this site.

Silver birch

Now this is a species which few will need the buds to identify – the distinct silver banded bark is visible behind the buds in this photograph!

The buds themselves are alternate and on small stems which protrude from the main twig.

Silver birch grow quickly but are relatively short lived – they are often one of the first pioneer species in a new woodland but soon become out-competed by larger, taller trees.

Cherry

Cherry is another difficult species as there are so many ornamental and hybrid varieties to choose from. The buds are alternate and dark brown with scales visible. Cherry is another species where the bark is very useful in the winter – the lines which look almost like horizontal cracks in their shiny bark are called lenticels and these are quite characteristic of cherries.

Although it is difficult to be sure of the exact species, it is likely that the Woodland Trust would have planted one of the native varieties – wild or bird cherry. Of the two, this one looks more like wild cherry (Prunus avium). Again, we can return to check this in the spring or summer!

English oak

The oak has tight clusters of buds especially at the tips. The buds are brown and have lots of scales.

One day this tree will probably tower above the others – think of the Major Oak in Sherwood Forest. For an example closer to home, there is a beautiful mature oak specimen along Belton Lane which you will probably pass on your way to Londonthorpe Woods – more on this magnificent tree in a later post!

Ash

The ash has one of the most distinctive buds – they form jet black pointed cones which really can’t be confused with much else. If you find buds of a similar shape but a different colour, such as grey, think of one of the other ashes which we sometimes encounter such as manna ash.

Hazel

Hazel buds are a greenish red in colour – a little like a red and green apple. They are alternate along the twig which itself is often hairy. Hazel provides a few extra clues in the winter time – the catkins (the male flowers) are often visible and if you look very carefully, you can see the tiny red female flowers on the same branch.

Another clue, depending on the management, is the growth form of hazel. It is often coppiced – that is cut down to the ground – and from here it sends up lots of new shoots which are often allowed to grow for several years before being cut back. The hazels in this plantation have been coppiced.

Hawthorn

The spiky shrubby hawthorn bush is fairly distinctive, even in the winter time. The spikes are generally quite visible and the buds compete with these along the twig. The buds are alternate and a similar dark reddish colour to the twigs.

Blackthorn

Blackthorn buds, by contrast with the hawthorn, are tiny little red dots which appear along the stem. The twigs are often long spikes and the buds appear along these. The colour of the bark of blackthorn is, as you might imagine quite dark, a blackish grey perhaps.

Dog Rose

Another species which you are unlikely to confuse with many others. Native roses grow lower to the ground than the other species in this plantation but can develop quite a shrubby form. The curved rose thorns, like a hawk’s talon, are quite distinctive and the rose hips, still present in January, are another key clue. The buds themselves are a slightly lurid red and grow alternately up the twig, alongside the thorns.