Looking after Spiny Norman

OK, in case you've not heard of him, Spiny Norman is a giant hedgehog from the Monty Python 'Piranha Brothers' sketch. I'm not going to write about offbeat-comedic imaginary hedgehogs, just the real ones you might see in your garden - more precisely the European hedgehog Erinaceus europaeus (there are seventeen species worldwide but only this one is found in Britain and last summer it was voted Britain's national species).

Months before I saw a hedgehog in our garden, I knew there was at least one around because of its droppings - black with invertebrate remains in it.

Traditionally a common and familiar species, hedgehogs have undergone a serious decline in Britain - this is difficult to measure but has been achieved with work such as the PTES Mammals on Roads Survey and the BHPS 2011 State of Britain's Hedgehogs report. The national population is estimated at around 30 million in 1950 but only 1.5 million by1995, and a further halving by 2001 in some areas. The reasons for this major decline are not entirely clear. However, some likely causes include:

• Agricultural intensification, in particular larger field sizes and losses of hedgerows and permanent grassland – also pesticide use which reduces prey availability.
• In urban areas (even small ones such as villages), smaller and tidier gardens with impassable fencing is likely to have reduced the amount of suitable urban habitat. 
• (Over)development, not only direct habitat loss, but fragmentation by buildings and roads which leads to  local populations becoming isolated and vulnerable to local extinction. 
• Increased road use - tens of thousands of hedgehogs are killed by vehicles each year and may be an importance cause of local decline in some areas.
• Competition with badgers (Meles meles) - where habitat provides effective cover and foraging opportunities, badgers and hedgehogs can coexist. However, badgers are a natural predator of (and competitor for food with) hedgehogs which therefore avoid sites with large numbers of badgers. The badger cull is still a stupid, unethical and politically motivated idea though. 
• Increased disease levels.

So what can you do?

• If you have a garden, don't be too tidy - allow leaves to accumulate, have a scruffy wildlife area and put in a hedgehog house. I made one out of scrap wood last autumn and it's already got a hedgehog in it (oh yes). I wouldn't have known except that the current bad weather damaged the roof and I found the hedgehog during (subsequently very careful and quiet) repairs earlier today. It really is important to resist the temptation to lift the lid for a peek... 
• Also, if you have a pond (as we do), make sure the sides are not steep all the way around as hedgehog will drown if they fall in and can't climb out - flatten/shallow out at least some of the edge and/or install slipways if you need to. 
• If possible, avoid using plastic mesh/netting or leaving plastic bottles, pots etc lying around as hedgehogs can get tangled, or get their heads stuck in them (their foraging behaviour means they are naturally inquisitive). Also, don't burn piles of grass mowings or other cut vegetation without checking first for hedgehogs (the same goes for bonfires). Similarly check compost heaps before turning them with a fork to avoid stabbing hedgehogs. 
• Also avoid using garden chemicals, including slug pellets, especially the more toxic versions (some are more mammal-friendly). 
• Leave some gaps/holes in fencing so hedgehogs can move between and in/out of gardens. 
• Don't feed hedgehogs with bread-and-milk - they can't digest it and it makes them ill. If you want to feed them, cat-food is fine. In dry conditions, shallow dishes of water are important too.

Our garden hedgehog house (note the staggered entrance-way and pile of dry leaves) with the waterproof roof removed.

I could go on, but there are plenty of online resources like this leaflet about 'Gardening with Hedgehogs', as well as opportunities to get more involved such as the Hedgehog Street project where you can become a Hedgehog Champion, and a variety of voluntary PTES surveys.

Garden hedgehog enjoying cat food and a dish of clean water. Nom.

Tiny denizens of the rot-hole

What with winter keeping most invertebrates out of sight, it's been a while since I wrote much of an entomological nature, but yesterday was a fine opportunity to head up to Beacon Hill nature reserve to see what was about. As well as chalk grassland (which will be more interesting when in flower), there is an interesting stand of beech woodland and associated scrub, including an ecologically important resource of dead wood (standing and fallen) and old mossy trees.

The base of a mossy beech tree.

These features mean that there is habitat for many fungi and dead-wood invertebrates and the evidence is everywhere - beetle boreholes (some opened by woodpeckers, one of which could be heard clearly in the woodland), wood in various stages of decay, insect-feeding birds such as a treecreeper (Certhia familiaris) and an intriguing-looking rot-hole with a large fungus and a tuft of hair poking out of it...

Rot-hole with fungus and tuft of hair

Looking inside, it had been lined with moss and hair, and was clearly a nest or roost of some sort, either of a bird or small mammal, and the fungus is (I think) an oyster mushroom Pleurotus ostreatus - if any mycologists would like to correct me on this, please do!

The inside of the rot-hole; at the base of the fungus, a layer of moss-and-hair bedding.

So, sample-pot in hand (like any good ecologist!), I took a pinch of the mossy bedding, including some soil/decayed wood from directly beneath it - after all, there are plenty of under-recorded parasites that live in vertebrate nests and you never know what you'll find. Back home, it was time to check what I'd found; some of the small inveretebrates such as Collembola (springtails) hide very effectively in material like this, so I find that adding some water to the sample in a watch-glass causes them to float to the surface and become easier to see. Indeed, doing this brought up a cluster of the common springtail Ceratophysella bengtssoni which can sometimes be found in large aggregations on the surface of soil and puddles, but may well still have been hibernating given the cold night-time temperatures at present.

Several Ceratophysella bengtssoni from the nest sample

These weren't the only springtails - Lepidocyrtus cyaneus and Neanura muscorum were also present, as was Tomocerus vulgaris from mossy dead-wood of a nearby tree. The samples included quite a few empty moulted skins, suggesting that these are not solely hibernation sites, but places where active feeding and growth occur - unsurprising as they mainly feed on fungal hyphae and decaying plant material (no shortage in this sample location). They are also an excellent group to look for in the winter as they can be found throughout the year - if you are interested in the UK species, Hopkin (2007) is an excellent place to start. However, Collembola are not the only soil/leaf-litter animals to be found. Hidden among the tangle of hair (mainly sheep I think) and plant fibres were two shed skins of an oribatid soil mite.

The shed skin of an oribatid soil mite

Oribatids are beyond my identification skills (I don't even know anyone who can ID them, though I do have a go at halacarids occasionally), but the shiny bulbous shape, the pointed mouthparts and the leg attachment points are all visible here. Though poorly known outside the realm of specialists, these mites are important in the decay process, feeding on a wide range of plant, animal and fungal organic material, with a minority being predatory - in fact they break down and process soil material in a similar way to earthworms even if they aren't as familiar or well-understood/studied.

Another species, common if often over-looked, and mainly found under bark or logs in woodland is the spotted snake millipede Blaniulus guttulatus. It is often considred a pest (e.g. in allotments) but probably only enters crops when damage has already occurred, such as by a 'primary' pest or some other mechanical means. They grow to around 20mm in length and are white with rows of red spots along the sides. The specimen I found however was a juvenile no more than about 3mm long (with few segments/spots), and the first early stage I've seen of this species.

Juvenile Blaniulus guttulatus

So, a few interesting finds - common species (no idea about the oribatid) but indicative of the small and often un-noticed soil/dead-wood fauna. Interestingly there were no mammal/bird nest-dwelling species (such as ticks or fleas), and no indication of exactly what had been using the hole - however, the presence of fine hairs and small dark elongate faeces, plus a lack of even small feathers suggest a mammal, presumably a rodent, rather than a bird.

Reference

Hopkin, S.P. (2007). A Key to the Collembola (Springtails) of Britain and Ireland. FSC, Shrewsbury.

Eyes in the back of my... back...

Mimicry using eyespots is widespread in nature - they are found in fish (such as the four-eyed butterflyfish Chaetodon capistratus which has them on the tail, so predators attack a non-lethal area or miss entirely), mammals (not only the 'obvious' ones such as leopards, but also the serval Leptailurus serval which has them on the backs of its ears for signalling to kittens while hunting), reptiles, birds and insects. Within the insects, butterflies and moths are probably best-known - many adult butterflies and moths have eyespots on the wings (the result of concentric pigment location around morphogenetic focus points), while the larva of the elephant hawkmoth Deilephila elpenor is famous for its conspicuous eye-like spots towards the head which are used to startle predators such as birds.

Elephant hawkmoth larva Deilephila elpenor showing eyespots

However, there are other invertebrates that show evidence of eyespots. I've previously written about bug (Hemiptera) nymphs possibly mimicing harvestmen, and today I noticed another - the common European garden spider Araneus diadematus. This is a very familiar species, often found on its orb-shaped web in gardens, and known for the pale cross-shaped marking (made from guanine which is a by-product of its protein metabolism) on the normally yellowish, orange or brown background of the top of the bulbous abdomen in females. Other common names include 'cross spider' and 'cross orbweaver', and males are smaller and less striking, though the markings are broadly similar.

Female Araneus diadematus showing the typical abdominal colour and cross-shaped marking

Male Araneus diadematus

So far, so good - but what about the eyespots I've mentioned. Well, the spiders are generally found either in the middle of their webs as shown above or tucked away in refuges at the ends of suspension silk lines. On webs they are typically head down and seen side on, either dorsally or ventrally. However, if you look stright down from the rear, a different pattern can be seen.

Female Araneus diadematus showing abdominal eyespots

To me, this is clear eyespot mimicry and makes adaptive sense - usually being head down, the rear of the abdomen is the part most likely to be presented to potential predators, namely birds, and therefore where eyespots that could startle them would be most useful. What I find more surprising is that I've never noticed this before despite having seen many specimens; more so that I can't find any other reports which suggests no-one else has either (or at least they written about it on the 'net). As ever, comments welcome!

Rubber-necking the rare Rothschild Giraffe

The giraffe (Giraffa camelopardalis) is of course a familiar and unmistakeable animal - it is however much less common than often imagined. It is split into a number of subspecies (up to nine, depending where taxonomic boundaries are placed) and even the most common, the Maasai giraffe G. c. tippelskirchi numbers no more than around 40,000 individuals in the wild. Several subspecies number no more than a few hundred, one of which, the Rothschild giraffe G. c. rothschildi has an estimated wild population of less than 650 (all in protected areas of East Africa) with almost as many kept in zoos around the world (including Marwell's conservation programme where I took these photos, although I have seen them wild in the Lake Baringo area of Kenya - it is sometimes known as the Baringo giraffe). They are readily identifiable from the coat colour/pattern, especially the pale 'socks' due to a lack of pattern on the lower leg.

Rothschild giraffes at Marwell - a surreal sight in southern England!

Given the small population size, and ongoing threats such as habitat loss (e.g. encroachment by human settlements), widespread poaching, and possibly hybridisation, this subspecies was added as Endangered on the IUCN Red List in 2010. It is also a poorly understood subspecies with no major research being undertaken on it prior to the ongoing Rothschild's Giraffe Project which aims to look at the behaviour and ecology of wild populations, in particular, ecological/habitat requirements, group dynamics, factors affecting behaviour, social structure, herd formation and relatedness, and from all of this, knowledge about how to formulate effective conservation plans (if you'd like to donate to the project, you can do so here).


Like all giraffes, both sexes have short blunt horns called ossicones (formed from ossified cartilage and fused to the skull) - these contain blood vessels and may be involved in temperature regulation. Males compete by engaging in 'necking' behaviour - this starts by rubbing and pushing, and can develop into full-blown contests as males swing their heads at each other and try to land blows with the ossicones. If you ever get the chance to see this, it's amazing - like a huge game of conkers.

Their necks are of course their best-known feature - with just the usual seven cervical vertebrae, each is about 30cm long and they have ball-and-socket articulations for flexibility. Proportionally, newborn young have short necks with most of the elongation happens after birth, otherwise giving birth would be problematic. When upright, the neck is supported by the nuchal ligament and large muscles which create the small hump seen at the base above the shoulders. When bending down to drink or graze (which also means splaying or bending the legs), the network of veins and arteries called the 'rete mirabile', plus valves in the jugular veins, prevent excessive blood flow to the brain. These are just some of the circulatory adaptations that allow the giraffe to function with such as long neck - its heart rate (about 150 beats/minute) is high for a large animal, its heart weighs around 11kg or more generating blood pressure about twice that in humans, and the skin of the lower legs is thick and tight to prevent too much blood pooling there.

Rothschild giraffe bending down to graze - note the splayed front legs.

I could go on about the bizarre anatony of the giraffe, but I won't - instead, why not have a look at the excellent 'Inside Nature's Giants' TV programme (videos are on Youtube) based on dissections by specialists in their field. It's amazing I can assure you!

The Truth of the Tooth: Cave Bear dentition, ecology and extinction

Lately I have written copiously about small invertebrates, particularly those found recently in our firewood store. So, having written five parts of the woodpile series (so far), I felt it was time for a brief departure - in terms of both time and scale as I have decided to look at some aspects of the Cave Bear Ursus spelaeus.

A Cave Bear skeleton in the typical (of museum displays) rearing posture.

Cave Bears lived in Pleistocene Europe (the Pleistocene epoch lasted from around 2.5 million to 11,700 years ago and covers the most recent series of repeated glaciations) and current evidence suggests they became extinct around 27,800 years ago. This means that they would have been encountered by humans and indeed they are depicted in cave art (albeit rarely e.g. at Les Combarelles cave in France). There is also possible evidence of Cave Bear worship by Neanderthals, such as at Drachenloch in Switzerland and Regourdou in France where the skulls of bears had clearly been arranged in and on man-made stone structures such as wall niches and a slab-covered pit. However, prehistoric anthropology, fascinating though it is, really isn't my area, so I'll stick with the more biological/ecological aspects. However, for an interesting overview of some aspects of human-Cave Bear interactions (focusing more on the earlier form of Cave Bear U. deningeri which disappeared around 100,000 years ago and may be an earlier species, a transitional subspecies or simply a pre-interglacial form of U. spelaeus), have a look at Stiner (1999). Taxonomic uncertainties aside, my interest was sparked when I bought a Cave Bear cheek tooth found in a cave in Romania, and dental evidence is where I will start.

Cave Bear cheek tooth, length 45mm.

This tooth is in pretty good condition (it's still shiny after about 40,000 years which shows just how tough tooth enamel is) and has an extensive grinding surface with a couple of large bluntly pointed cusps. Cave Bears lost their premolars as they evolved, a feature which has been used to suggest a highly herbivorous diet (e.g. Kurtén, 1976). The last premolar evolved as a molar (molarisation) which allowed tough plant material to be chewed more effectively (and hence more more food energy to be extracted) due to the increased number of cusps and cutting edges of the teeth, especially in the elongated last molar. Their teeth also show more wear than in most modern bears which again suggests a herbivorous diet with a large component of tough/fibrous materials, although detailed analysis indicates that tubers and other gritty foods were not a major part of their diet, unlike for modern Brown Bears U. arctos (Pinto Llona et al., 2005). However, varying threads of research in this area, including evidence for some cannibalistic scavenging (Pacher, 2000) has led to current scientific opinion tending towards Cave Bears being more herbivorous than modern bears of the genus Ursus, but still omnivorous to some extent. Recent re-examination of skull and tooth morphology (Figueirido et al., 2009) and analysis of the regional variation in bone isotope composition, especially nitrogen-15 (Richards et al., 2008; Trinkaus & Richards, 2008) both support this idea of omnivory and some variation in diet.

The same cheek tooth showing the pattern of the crown. The large grinding surface covers the left side of the tooth and the lower right side, with the pointed cusps to the upper right. The orange deposits in the grooves of the enamel are the remains of soil, although the right-hand end shows an area of worn (yellowish and not shiny) enamel at the base of the large cusp.

With advances in molecular biological techniques, the possibility of investigating cave bear genetics arose and in 2005, nuclear DNA extracted from a Cave Bear tooth around 42-44,000 years old was sequenced. This indicated that the Cave Bear was more closely related to the Brown Bear and Polar Bear U. maritimus than to the North American Black Bear U. americanus (Noonan et al., 2005) and supported earlier similar findings using mitochondrial DNA (Loreille et al., 2001). Interestingly, investigation of the fine structure of Cave Bear tooth enamel (the 'rods' or 'prisms' that form the basic units of enamel) shows that it retained carnivore-like characteristics despite the clear adaptation to a largely herbivorous diet. Thus, changes in broad dental anatomy driven by dietary specialisation can occur without the equivalent changes in enamel structure (von Koenigswald, 1992), meaning that Cave Bears had herbivore-shaped cheek teeth with carnivore-like enamel.

So, we have an extinct species of bear clearly adapted to a specialised herbivorous diet with some elements of omnivory and variation. As well as the genetic evidence mentioned above, its skeleton is similar to that of the modern Brown Bear, with the two species appearing to have diverged around 1.2 to 1.4 million years ago (Loreille et al., 2001) i.e. prior to the splitting of Brown and Polar Bears which may have occurred around 850,000 years ago, although this estimate is somewhat uncertain (Swenson, 2007). Males averaged 400–500 kg with females around half this weight at 225–250 kg (Christiansen, 1999), similar to the range for the largest modern bears, noting that they were larger during glaciations and smaller during interglacial periods (MacDonald, 1993), probably as an adaptation to adjust heat loss rate as larger animals have smaller surface area:volume ratios. The reason for its extinction is uncertain. It is unlikely to simply be due to its specialised diet and restricted geographical range ecologically 'marooning' it during post-glocial warming - after all, it had survived several similar changes in condition previously and there is possible genetic evidence of a decline starting some 25,000 years prior to its extinction (Stiller et al., 2010). Also, as noted above there is strong evidence for the species' ability to vary its diet. Instead, it is likely that there was a complex interplay of factors, possibly involving competition with humans for cave habitat, maybe specifically for hibernation sites as Cave Bears did not appear to use alternatives such as forest thickets and failure to find a hibernation site would lead to death. Despite numerous media reports taking the 2010 paper by Stiller et al. to be definitive evidence of competition with humans rather than changing climatic conditions to be the cause of Cave Bear extinction, there is still genuine scientific disagreement and research is ongoing. Further genetic work (Bon et al., 2011) does however show reduced genetic diversity from specimens in France originating from the period directly prior to extinction (genetic diversity is greater for specimens prior to this), again indicating a species under stress during human colonisation of the area - and the possibility of competition for hibernation caves.


References

Bon, C., Berthonaud, V., Fosse, P., Gély, B., Maksud, F., Vitalis, R., Philippe, M., van der Plicht, J. & Elalouf, J.-M. (2011). Low regional diversity of late cave bears mitochondrial DNA at the time of Chauvet Aurignacian paintings. Journal of Archaeological Science 38 (8): 1886-1895. 
Christiansen, P. (1999). What size were Arctodus simus and Ursus spelaeus (Carnivora: Ursidae)? Annales Zoologici Fennici 36: 93–102.
Figueirido, B., Palmqvist, P. & Pérez-Claros, J.A. (2009). Ecomorphological correlates of craniodental variation in bears and paleobiological implications for extinct taxa: an approach based on geometric morphometrics. Journal of Zoology 277 (1): 70–80.

Kurtén, B. (1976). The Cave Bear Story. Life and Death of a Vanished Animal. Columbia University Press, New York.
Loreille, O., Orlando, L., Patou-Mathis, M., Philippe, M., Taberlet, P. & Hänni, C. (2001). Ancient DNA analysis reveals divergence of the cave bear, Ursus spelaeus, and brown bear, Ursus arctos, lineages. Current Biology 11 (3): 200–203.
MacDonald, D. (1993). The Velvet Claw: A Natural History of the Carnivores. BBC, London.

Noonan, J.P., Hofreiter, M., Smith, D., Priest, J.R., Rohland, N., Rabeder, G., Krause, J., Detter, J.C., Pääbo, S. & Rubin, E.M. (2005). Genomic Sequencing of Pleistocene Cave Bears. Science 309 (5734): 597–599.
Pacher, M. (2000). Taphonomische Untersuchungen der Höhlenbären-Fundstellen in der Schwabenreith-Höhle bei Lunz am See (Niederösterreich). Beiträge zur Paläontologie 25: 11–85.
Pinto Llona, A.C., Andrews, P. & Etxeberrıa, P. (2005). Taphonomy and Palaeoecology of Cave Bears from the Quaternary of Cantabrian Spain. Fondacion de Asturias/Du Pont Iberica/The Natural History Museum, Grafinsa, Oviedo.
Richards, M.P, Pacher, M., Stiller, M., Quilès, J., Hofreiter, M., Constantin, S., Zilhão, J. & Trinkaus, E. (2008). Isotopic evidence for omnivory among European cave bears: Late Pleistocene Ursus spelaeus from the Peştera cu Oase, Romania. Proceedings of the National Academy of Sciences of the United States of America 105 (2): 600–604.
Stiller, M., Baryshnikov, G., Bocherens, H., Grandal d'Anglade, A., Hilpert, B., Munzel, S.C., Pinhasi, R., Rabeder, G., Rosendahl, W., Trinkaus, E., Hofreiter, M. & Knapp, M. (2010). Withering Away – 25,000 Years of Genetic Decline Preceded Cave Bear Extinction. Molecular Biology and Evolution 27 (5): 975–978.


Stiner, M.C. (1999). Cave bear ecology and interactions with Pleistocene humans. Ursus 11: 41–58.
Swenson, J.E. (2007). Økologi hos en voksende bjørnebestand – Forvaltning når bjørnen har kommet tilbake. Det Skandinaviske Bjørneprosjektet [in Swedish] [accessed 15/11/2011].

Trinkaus, E. & Richards, M. P. (2008). Reply to Grandal and Fernández: Hibernation can also cause high δ15N values in cave bears. Proceedings of the National Academy of Sciences of the United States of America 105 (11): E15.
von Koenigswald, W. (1992). Tooth enamel of the cave bear (Ursus spelaeus) and the relationship between diet and enamel structures. Annales Zoologici Fennici 28: 217–227.

Bird pellets - they're not all about owls

Any book about the signs of wildlife will mention owl pellets - there's even an excellent little book about analysing just these (Yalden 2009), plus a fold-out laminated guide (Thomas & Shields 2008). However, many other carnivorous and omnivorous birds also produce pellets and so regurgitate indigestible material - raptors, gulls, corvids; if I remember rightly, Chris Packham even showed a kingfisher pellet on Springwatch (or was it Autumnwatch?). So, when I recently found a Tawny Owl (Strix aluco) pellet the same day as a Blackbird (Turdus merula) pellet, what could I do but dissect and compare them...

With owl pellets so well documented, I started with this one - approximately 55mm long and 30mm wide in the middle and consisting of greyish fur with some emergent bones. The habitat (under a couple of tall trees in a suburban location where I have heard tawny owls) plus the overall size, form and structure/content, lead me to ID it as a tawny owl pellet.

The owl pellet

The method is straightforward enough (if a little time-consuming and fiddly) - put the pellet in a white tray and dissect with mounted needles and fine tweezers. Pellets can be wetted, but I decided to leave it dry (either is fine). I started with the larger bones and found that, unsurprisingly, the owl had been eating voles - Field Vole (Microtus agrestis) and Bank Vole (Myodes glareolus).

Field vole lower jaw - note the toothless curved area (diastema) on the right

Field vole lower jaw - note the alternating loops of the teeth

Bank vole lower jaw - note the opposite loops of the teeth

A long bone of a small mammal, presumably one of the voles. The tiny yellowish spike near the upper left side of the bone is the chaeta (bristle) of an earthworm.

A tiny bone - assumed to be a vole 'toe' bone

Working through the pellet, another feature soon became obvious - the presence of a large amount of sand. This is a good indication that the owl had been feeding on earthworms and so ingesting sandy soil - something confirmed by the numerous chaetae present (there's one in the 'long bone' photo above). Overall, nothing too surprising - field voles are a favoured prey of many owls (though less so for tawny owls), and earthworms are comminly found. If I were undertaking a detailed study of owl diet or local mammal availability, I could weigh the different components to derive more information - in this case it's just a one-off pellet.

Now, onto the blackbird pellet. Firstly how do I know it's a blackbird pellet? Well, there the size (about 20mm long) and clear presence of invertebrate food (see below), but it was also found in my garden under one of the bird's favourite perches, and to make it even easier, I saw it deposit the pellet! So, what was in it?

Blackbird pellet

Well, the first thing that leaps out is the presence of complete millipedes - two were present and were clearly not easy to digest. I have yet to identify them, but they appear to be the same species - maybe Tachypodoiulus or Cylindroiulus - I'll need to check the telson (last 'tail' segment) to be sure. However, this is only about half the pellet - there are lots of smaller fragments, including a small green object bottom left...

A fragment of insect cuticle

The same fragment from the inside

This piece of cuticle is hard to ID, but my feeling is that it may be part of a shieldbug, though I can't be certain and I don't know of the depth of colour might change during its time inside the bird. There were many many other arthropod fragments - pieces of cuticle, antennae (at least some from small beetles, possibly Carabidae, ground beetles), bits of plant material, and various mystery structures. As with the tawny owl, there were also earthworm chaetae - given how often blackbirds are seen pulling at worms, this is unsurprising!

These are only single examples of pellets (do blackbird pellets often contain a large proportion of millipede remains?), so I can draw few conclusions beyond simply being interested in what could be found. However, I have kept the resulting bits (my wife is so proud...) and will look out for more to see if more data can be gathered. I've also found a nearby otter (Lutra lutra) latrine with numerous spraints, and have a copy of Conroy et al. (2005), so don't be too surprised if a future post invoves close-ups of the contents of otter poo...

References

Conroy, J.W.H., Watt, J., Webb, J.B. & Jones, A. (2005). A Guide to the Identification of Prey remains in Otter Spraint (3rd ed.). The Mammal Society, Southampton.
Thomas, L. & Shields, C. (2008). Guide to British Owls and Owl Pellets. FSC, Preston Montford.

Yalden, D.W. (2009). The Analysis of Owl Pellets (4th ed.). The Mammal Society, Southampton.

Bushbuck: two species where there was one

Back in the day, the bushbuck was considered a single species, Tragelaphus scriptus, found in various habitats across much of sub-Saharan Africa. Recently however, genetic studies have indicated that T. scriptus is actually a complex of two distinct species, the Kéwel (T. scriptus) and the Imbabala (T. sylvaticus). This evidence shows that these two bushbuck species are more closely related to other tragelaphines than to each other; the Imbabala being closest to the Bongo (T. eurycerus) and Sitatunga (T. spekeii), and the Kéwel to the Nyala (T. angasii) (Moodley et al. 2009).

The Kéwel is found from West Africa, across the Sahel into East Africa, and as far south as Angola and the Democratic Republic of Congo (DRC). Meanwhile, the Imbabala is found from the Cape northwards to Angola, Zambia and East Africa, meaning that the two species’ ranges overlap in parts of Angola, DRC and East Africa.

The Kéwel is the smaller of the two, and shows clear stripes and patterning on a reddish to yellowish background; there is little or no sexual dimorphism in this ground colour. In contrast, the Imbabala shows considerable colour variation with geography and habitat, especially in males (yellow to red-brown, through brown and olive to almost black), and only the most genetically ancient of populations (from Angola, Zambia, southern DRC, Botswana and northern Zimbabwe) have any significant striping. Even in these cases the horizontal stripe, where it exists, is formed of a series of spots rather than the solid striping of the Kéwel. never occurs. Mountain-dwelling forms of the Imbabala (Gregory Rift Highlands, Mt. Elgon, Imatong Mountains and Ethiopian Highlands) appear larger and are dark with little or no pattern. Until recently, most bushbuck studies focused on the Imbabala, hence little was known about the biology of the Kéwel beyond what could be obtained from museum specimens and hunting trophies.

Imbalala bushbuck from Zimbabwe (courtesy of Graeme Guy). For a kewel image from The Gambia see here.

Both species are primarily browsers, but will eat other plant matter too. They can be active at any time of day, although are more likely to be nocturnal near humans; their most active times are however early morning and parts of the night, so may appear nocturnal in any case. Most are solitary, with some living in pairs; all have a ‘home range’ of around 5 hectares in the savannah (larger in forests), although these ranges do overlap.

Although the split into two species is fairly well understood (even if most non-scientific sources still refer to a single ‘bushbuck’), the more detailed taxonomy remains disputed with numerous potential subspecies and ecotypes having been described. For example, analysis of mt-DNA sequences (cytochrome b and control region) by Moodley & Bruford (2007) identified 23 phylogenetically distinct groups (‘ecotypes’) whose distribution correlated well with the pan-African eco-regions described by Olsen et al. (2001). 19 of these ecotypes corresponded with previously suggested subspecies, while six other haplotypes were newly recognized forms in the Volta region, Niger, Angola. and Luangwa and Zambesi Valleys. However, further research is onging to clarify the taxonomic status of bushbuck species, subspecies and ecotypes, so the situation is likely to remain somewhat fluid for a while – however, this does provide an opportunity to link the use of genetics in taxonomy to large-scale conservation in Africa, given the widespread distribution of bushbuck (in the broad sense) and apparent more local/region distribution of subspecies and ecotypes (Wronski 2009).

References

Moodley, Y. & Bruford, M.W. (2007). Molecular Biogeography: Towards an Integrated Framework for Conserving Pan-African Biodiversity. PLoS ONE 2(5): e454. doi:10.1371/journal.pone.0000454

Moodley, Y., Bruford, M., Bleidorn, C., Wronski, T., Apio, A., & Plath, M. (2009). Analysis of mitochondrial DNA data reveals non-monophyly in the bushbuck (Tragelaphus scriptus) complex Mammalian Biology - Zeitschrift fur Saugetierkunde, 74 (5), 418-422 DOI: 10.1016/j.mambio.2008.05.003

Olson, D.M., Dinerstein, E., Wikramanayake, E.D., Burgess, N.D. & Powell, G.V.N. (2001). Terrestrial ecoregions of the world: a new map of life on earth. BioScience 51: 933-937.

Wronski, T. (2009). Bushbuck, harnessed antelope or both? Gnusletter 28(1): 17-19.

Reindeer in Britain: ecology, conservation and welfare outside their native range

Known as caribou in North America, reindeer (Rangifer tarandus) were once widespread in Europe reaching as far south as Spain, but are now mainly found in Norway and parts of Russia, in some cases being found wild alongside domesticated herds. Whilst their bones occur frequently in prehistoric middens, the last reliable record in Britain was approximately 8,300 years ago after which they disappeared (later records are uncertain), probably due to climate change, although hunting pressure may have also been a factor. However, 29 reindeer were reintroduced to Scotland by Swedish Laplander Mikel Utsi in the 1950s. Despite some climate-related difficulties such as troublesome insects, the herd generally thrived, although mortality rates are raised due to dog attacks and eating discarded litter. The herd is now managed at 130-150 animals across two areas - the Cairngorms and the Cromdale Hills – and are the only genuinely wild (if managed and visited) reindeer in Britain. There are other more-or-less free-ranging herds such as at the Trevarno Estate near Helston in Cornwall. These animals were introduced as a Christmas attraction in 2008 and have acclimatised to the warmer-than-Arctic weather, even producing the first calf in England for probably thousands of years in spring 2010.

Reindeer on short montane grassland.

The lack of fecundity is unsurprising given the challenge of the English climate (OK, it’s cold at the moment, but...) especially in the south-west. Reindeer are cold-adapted and fond of their Arctic diet of mushrooms, lichens and other vegetation with their associated minerals. Reindeer’s cold-adaptations include short legs, ears and tail, a hairy muzzle, broad flat hooves for walking on snow (winter) and boggy ground (summer), dense winter coats and particularly rich milk (more than 20% fat while human milk is 3.5% fat) to help the young survive and grow in cold conditions. They are also poorly adapted to the diseases and parasites found in the warmer areas of Britain, with reports of animals dying prematurely having been imported for festive grottos and parades (especially following relaxation of quarantine rules), and subsequently being exposed to diseases from British livestock, along with issues of poor diet and welfare, and the stress of transportation from large semi-wild herds.

Reindeer on grasslands below mountains.

Research by Hughes et al. (2008) on Canadian animals suggests that even in the Arctic, parasites may impact populations by worsening the effects of forage availability (which is seasonal and limited) on individuals’ condition, fecundity and survival. The study showed that, in females over 2 years old, by the end of winter there was a significant decrease in body weight with increased nematode burden, and a decrease in back fat depth with increased warble-fly (Hypoderma tarandi) abundance (which was also associated with reduced chance of being pregnant). Although not directly relevant to the British population, it is possible that muskox (Ovibos moschatus) share some parasite species with reindeer, leading to elevated burdens in the co-host. Thus, parasites may have contributed to a previous shift in winter range by reindeer herds, suggesting in effect a type of competition between the two species. If a similar effect were seen in Britain, reindeer would be unable to shift away from the effects of disease and parasites as most are in captivity (often with relatively inexperienced owners/handlers), while the wild Scottish herd is constrained within a limited area. Thus welfare and animal husbandry standards need to be high (at present, reindeer owners do not have to report unusual deaths to the Veterinary Laboratories Agency, so rigorous research and scrutiny is difficult) and it is important to understand the ecology of such an Arctic-adapted species when introduced into a warming temperate environment.

Lastly, predation; there may be none of the large 'typical' predators such as wolves in Britain (yet), but there is video evidence from Finland of golden eagles (Aquila chrysaetos) hunting reindeer calves - I've not heard of this happening in Britain, but with golden eagle numbers having increased in Scotland, I would be very interested to hear if this behaviour has been witnessed...

For general background information on reindeer, click here.

Bye for now - and season's greetings! Got any lichen...?

Reference

Hughes, J., Albon, S., Irvine, R., & Woodin, S. (2008). Is there a cost of parasites to caribou? Parasitology, 136 (02), 253-265 DOI: 10.1017/S0031182008005246

Picture credit

Thanks to ‘Animal Photos’ for making these images available via the Version 3.0 Attribution-ShareAlike Creative Commons License.