Wild Mammals of London

Arguably the single biggest threat to the continued survival of animal and plant species is loss of habitat. Even if an animal isn't actively hunted, the ever-growing human population means that there are simply fewer suitable places for them to live. Logging and the expansion of agriculture are probably the biggest factors here, at least in terms of the area affected, but it's hard to argue that the recent growth of urban sprawl isn't another.

The urban environment is obviously a difficult or impossible one for most wild mammals to exploit. House mice and rats are an obvious exception, and there are also domesticated pets, but for truly wild creatures it's a different matter. While it may no longer have (say) bison or wolves, upstate New York is still home to seven species of shrew, three moles, four hares or rabbits, 22 different kinds of rodent, ten bats, nine mustelids, two foxes, and three deer, plus coyotes, bobcats, raccoons, striped skunks, and black bears. Manhattan... not so much.

Small British Mammals: Hedgehogs

There can be few British mammals more distinctive and well-loved than the hedgehog. Indeed, a 2016 poll found that it is, by a substantial margin, Britain's favourite mammal. (For what it's worth, and by a similar margin, the robin is apparently our favourite bird).

The animal that Brits simply call "the hedgehog" is more accurately the European hedgehog (Erinaceus europaeus), and it's found through pretty much the entirety of western Europe. In fact, across much of the continent, the eastern border of its occurrence is very roughly where the old Iron Curtain used to be. That's a simplification, of course, and aside from some border regions of former 'Eastern Bloc' countries, they are also found quite extensively in the Czech Republic, Estonia and parts of north-west Russia. They are also common on several larger islands, including Ireland, Corsica, Sardinia, and Sicily, and, in more recent times, they have been introduced to the Azores.

Fossilised Hedgehog Ankles?

Many moons ago, back when I was at University (and studying zoology formally, instead of just as a hobby), the great majority of invertebrate-eating, non-flying, placental mammals were placed in a single group, the Insectivores. Even then there was some suspicion that this was a bit of a "wastebasket taxon", a group of animals placed together because it wasn't obvious what else to do with them. Molecular phylogenetics and cladistics were still in their infancy in those days, and, so far as I recall, the latter was never even mentioned.

Since then, things have changed, giving us a better picture of evolutionary relationships overall. Among other things, the number of animals that really belonged in the Insectivora was whittled away, as we discovered where the things we'd thrown into the wastebasket really belonged. The rump of the group, a genuine evolutionary unit that now goes by the less accessible name of "Eulipotyphla", does, however, still contain its most familiar members, animals such as shrews, moles, and hedgehogs.

Part of the problem is that these are relatively unspecialised mammals, in the sense that they remain broadly similar to what we think the first ever placentals looked like. Moles, of course, have adapted to a burrowing underground lifestyle that makes them fairly distinctive, but this is rather less true of their relatives. This also makes things difficult when we're looking at fossils, and we're trying to figure out just how far down the placental family tree any given suspected small insectivorous animal actually is.