Thursday, May 2, 2013
H is for HEDGEHOG
A hedgehog is any of the spiny mammals of the sub-family Erinaceinae, which is in order Erinaceomorpha. There are seventeen species of hedgehog in five genera, found through parts of Europe, Asia, Africa and New Zealand (by introduction). There are no hedgehogs native to Australia, and no living species native to the Americas. Hedgehogs share distant ancestry with shrews (order Soricidae), with gymnures possibly being the intermediate link, and have changed little over the last 15 million years. Like many of the first mammals they have adapted to a nocturnal, insectivorous way of life. Hedgehogs' spiny protection resembles that of the unrelated rodent porcupines and monotreme echidnas.
One reason I chose the hedgehog for my 'H' is because when we were in Wanaka, *New Zealand back in 1982 we were having a stroll with a couple of English friends and we came across a hedgehog wandering across the road. Phil picked it up to put it out of danger and friend Frank said "Oh, put that down, they are full of fleas!" We spoke to someone about this later on who revealed that hedgehogs in New Zealand don't have fleas as apparently with the long journey from the UK to NZ years ago the fleas on the hedgehogs on board ship all died. Whether or not this is true would have to be verified but I also think they are a fascinating animal.
The name hedgehog came into use around the year 1450, derived from the Middle English 'heyghoge', from 'heyg', 'hegge' ("hedge"), because it frequents hedgerows, and 'hoge', 'hogge' ("hog"), from its pig-like snout. Other names include urchin, hedge-pig and furze-pig.
Hedgehogs are easily recognised by their spines, which are hollow hairs made stiff with keratin. Their spines unlike the quills of porcupines, cannot be easily removed from the hedgehog. However, its effectiveness depends on the number of spines, and since some of the desert hedgehogs evolved to carry less weight. they are much more likely to run away and sometimes even attack the intruder, trying to ram into the intruder with its spines, and rolling as a last resort. This results in a different number of predators for different species: while forest hedgehogs have relatively few, primarily birds (especially owls) and ferrets, smaller species like the long-eared hedgehog are preyed on by foxes, wolves and mongooses. (Why did I think that should be mongeese?)
The spines of the hedgehogs serve a useful purpose that enables the hedgehog to bounce! Hedgehogs don't really have a fear of falling and they will quite happily walk off the edge of something, as they fall they curl and the muscles at the base of the spines ac as a kind of shock absorber saving the hedgehog from injury. After a short pause the hedgehog will unball, twist and flip over and wander off as if nothing had happened. Incidentally, hedgehogs are quite good climbers and swimmers as well.
Hedgehogs are primarily nocturnal, although, depending on the species, they may be more or leses active during the day. The hedgehog sleeps for a large portion of the daytime either under cover of bush, grass or rock or in a hole in the ground. Again, different species can have slightly different habits, but in general hedgehogs dig dens for shelter. All wild hedgehogs can hibernate, although not all do; hibernation depends on temperature, species, and abundance of food.
The hedgehog's back is made up of two large muscles, which control the positioning of its quills. There are about 5,000 to 6,500 quills on the average hedgehog, and these are durable on the outside, while being filled with air pockets on the inside. The hedgehog uses it quills to protect itself from predators, using muscles which draw their quilled skin to cover their full body, and pulling in the parts of their bodies not covered, such as their head, feet and belly. **This form of defense is the hedgehog's most successful, but it usually their last resort.
Hedgehogs are fairly vocal and communicate through a combination of grunts, snuffles and/or squeals, depending on the species.
Hedgehogs occasionally perform a ritual called anointing (see below). When the animal encounters a new scent, it will lick and bite the source, then form a scented froth in its mouth and paste it on its spines with its tongue. The specific purpose of this ritual is unknown, but some experts believe anointing camouflages the hedgehog with the new scent of the area and provides a possible poison or source of infection to predators poked by their spines. Anointing is sometimes also called anting because of a similar behaviour in birds.
Similar to opossums, mice and moles, hedgehogs have some natural immunity against snake venom due to the protein erinacin in the animal's muscular structure (although it is only available in a small percentage and a viper bite, for example, may kill the hedgehog anyway.
Hedgehogs feed on insects, snails, frogs and toads, snakes, bird eggs, carrion, mushrooms, grass roots, berries, melons and watermelons. Berries constitute a major part of an Afghan hedgehog's diet in early spring after hibernation.
Depending on species, the gestation period is 35-58 days and the average litter is 3-4 newborns for larger species and 5-6 for smaller ones. As with many animals, it is not unusual for an adult male hedgehog to kill newborn males.
Hedgehogs have a relatively long lifespan for their size. Larger species live 4-7 years in the wild (some have been recorded up to 16 years), and smaller species live 2-4 years (4-7 in captivity), compared to a mouse at 2 years and a large rat at 3-5 years. Lack of predators and controlled diet contribute to a longer lifespan in captivity (8-10 years depending on size).
*In areas where hedgehogs have been introduced, such as New Zealand and the islands of Scotland, the hedgehog has become a pest. In New Zealand it causes immense damage to native species including insects, snails, lizards, and ground-nesting birds, particularly shore birds. As with many introduced animals, it lacks natural predators. With overpopulation, it kills off more insects than initially intended and expands its diet to include things such as snails, worms the eggs of wading birds.
Hedgehogs suffer many diseases common to humans and these include cancer, fatty liver disease and cardiovascular disease. Fatty liver disease is believed by many to be caused by bad diet as hedgehogs will eagerly eat foods that are high in fat and sugar. Having a metabolism adapted for low-fat. protein-rich insects, this leads to common problems of obesity. Fatty liver disease is one sign and heart disease another.
I realise this really is a very, very long post but from it, for what it's worth, you should have learned all you wanted to know, or didn't want to know, about the hedgehog.
P.S. **I was telling Phil that the hedgehog was my "H" post and he was reading some of it and said that he had encountered hundreds of hedgehogs back in the UK and they nearly always rolled into a ball if you touched them. He also said it was a known fact that when the cows lay down in the fields at night hedgehogs would come and suckle the cows. Unbelievable but true.