British Wildlife of the Week (Special)

Made in Britain

Most islands are rich in unique species of animals and plants that are found nowhere else in the world. New Zealand, for example, is home to the kiwi, the kākāpō, and the takahē, along with many other rare flightless birds, while Madagascar is famous for its lemurs, fossas, and tenrecs. The British Isles, by comparison, has very few animals that it can exclusively call its own. That’s because Britain was only isolated from mainland Europe relatively recently, and the 8,000 years since meltwater from the end of the last Ice Age created the English Channel has not provided much time for new species to evolve.

Many of the endemic animals that live in Britain are endemic subspecies – they are uniquely British variants of species found elsewhere in the world. They include the red grouse, which is a race of willow ptarmigan; the Irish hare, a subspecies of mountain hare found only in Ireland; and several different, unique types of wren that live only on a few remote Scottish islands (which you can read more about here).

But if you delve a little deeper, you will discover that we do, in fact, have perhaps 300 fully-fledged endemic species living on our islands, many of which are quite obscure. Here is a list of just five of them:

1. Horrid Ground-Weaver

The horrid ground-weaver spider may have an unpleasant-sounding name, but it actually isn’t dangerous to humans in the slightest. First discovered in 1989, this tiny money spider is extremely rare, found only in an area of Plymouth that is smaller than 1km². Until 2016, only nine specimens had ever been found, seven males and two females, all within disused limestone quarries just to the east of the city centre. But then a new population was discovered on an industrial site, and the species was photographed and filmed alive for the first time.

Plans to build over 50 houses on one of the four sites in which the spider lives were submitted to Plymouth City Council in 2014. Although it was rejected, the developer behind the building proposals appealed against the council’s decision, triggering a formal planning enquiry. A year later, an online petition to save the horrid ground-weaver was started by the conservation group Buglife and was signed by almost 10,000 people. Fortunately, the Planning Inspector deciding the appeal ruled that building development could not go ahead due to concern for rare wildlife, particularly the horrid ground-weaver. The IUCN rates this spider as Critically Endangered, for globally it is found nowhere else apart from this one small area of Plymouth.

2. Derbyshire Feathermoss

Britain is home to a fair few endemic species of plants because they can form new species significantly faster than animals. They include the Scottish primrose, the Irish whitebeam tree, and what is quite possibly the world’s rarest species of moss, the Derbyshire feathermoss. The entire population of this moss is restricted to a patch of ground little more than 3m² on a single rock along a river in the Derbyshire Peak District. The exact location is kept a secret to protect it.

3. Ivell’s Sea Anemone

Some of the endemic animals that Britain is home to are virtually unknown outside specialist circles. Take, for example, Ivell’s sea anemone, a tiny, worm-like anemone no greater than 2 cm in length that has 12 transparent tentacles arranged in two circles. Globally, it is known from only one site, Widewater Lagoon in West Sussex, where it was first discovered by (and later named after) Richard Ivell in 1972.

A decade later, however, the anemone could no longer be found within the lagoon, and, despite several intensive searches, has not been seen since. Given the creature’s tiny size and proclivity for burrowing in mud, it’s possible that it still survives, if not in Widewater Lagoon then perhaps somewhere else in the country. But many conservationists believe that, due to a lack of suitable habitat for this very specialised creature, it has disappeared forever and should be declared officially extinct. If this is indeed the case, the demise of Ivell’s sea anemone is Britain’s first reported endemic loss in recent years.

4. Lundy Cabbage

The island of Lundy, off the north coast of Devon, where the Bristol Channel meets the Atlantic Ocean, is only 5.6 km long by 800 m wide, but it is still very rich in wildlife. If you visit this wonderful site, you may well spot its famous puffins, the tough, hardy Lundy pony, and the primitive Soay sheep (introduced to the island from the isle of Soay in the St Kilda archipelago in Scotland by Martin Coles Harman soon after he purchased Lundy in 1924). But there is also a botanical rarity here: the Lundy cabbage. Granted, it’s not much to look at, but Lundy is the only place in the world where this plant grows in the wild.

Perhaps of greater interest is the fact that living and feeding on this cabbage are two rare and unusual types of insect, the Lundy cabbage flea beetle and the Lundy cabbage weevil. These are also endemic to the island of Lundy, and in fact are only found on this particular plant.

5. Scottish Crossbill

Britain may have relatively few endemic species, but it has even fewer endemic vertebrates. Almost all of the ones that we do have are fish. In some upland areas, retreating glaciers following the last Ice Age left meltwater in hollows that had been carved out by the movement of the ice. In these depressions, Arctic species of fish survived, often due to the sheer depths of the lakes and the colder temperatures. Isolated for thousands of years, some of these fish have become slightly different species, and we’ve already looked at one of these on the blog before – the vendace.

But when it comes to fully-fledged endemic land vertebrates, we have only one: the Scottish crossbill (seen in the image at the top of the page). As we’ve already discussed in our article about unusual bird beaks, crossbills are so-named because the upper mandible of their bill crosses over the lower one, having evolved to enable the bird to prise open pine cones to obtain the flaky seeds within. Here in Britain, three species of crossbill can be found. By far the most widespread and numerous is the common, or red, crossbill, which lives in evergreen forests across much of the UK. The parrot crossbill, which primarily lives in Scandinavia and Russia and is slightly bulkier, also appears here in small numbers and occasionally breeds. Then there’s the Scottish crossbill, which is found only in the pine forests of the Scottish Highlands.

In Scotland, where all three species occur, it can be exceedingly difficult to tell the crossbills apart without very close examination. They share the same plumage and colours, and they behave and look much the same, except for small variations in the depth of their beaks. In fact, even the birds themselves seem to get confused sometimes, for they have been known to mate with each other, leading to cross-bred crossbills.

This similarity meant that the Scottish crossbill has had a rather hard time trying to earn its endemic distinction. It was long regarded as just a subspecies of either the red crossbill or parrot crossbill, or even a hybrid of the two. But in 2006, it was finally confirmed as its own species. This was not on the basis of its physical appearance, but due to its distinctive flight and its subtly different bird song, which some say has a ‘Scottish accent’ to it.

This has been our 50th and final British Wildlife of the Week article (for now at least). We’ve been doing them for almost exactly a year now, with only a small break over Christmas. The Nature Nook will be quite busy over the next month or so, which means the blog will be taking a hiatus for a while. We’ll probably be back to regular posting in September, but in the meantime, if you want to check out any of our previous British Wildlife of the Week posts, please check out our archives.