Fringilla papillomavirus

The British bird population is prone to a whole manner of different diseases, infections and parasites. The impact of infectious diseases on our bird populations is something of considerable interest to me as a naturalist and something I feel needs more attention. Fringilla papillomavirus is a disease which is quite common amongst chaffinch in Britain and is regularly and incorrectly referred to as bumblefoot which is a bacterial infection caused by an entirely different organism. F.papillomavirus causes what is known as viral papillomas or warts for want a better word. This disease affects all ages of chaffinch of both sexes and to a lesser extent brambling. We tend to find it clustered within populations and localities, typically affecting a small portion of the population.
The disease consists of a warty covering of the foot and leg (tarsometatarsus). This is typically a mass of irregularly shaped growths containing nodules and fissures (see below) made up of excessive growth of keratinised layers of skin. Affected birds are usually in good health although they may struggle to walk on one foot and often hop. There is little evidence that is has significant affects on populations at local or national levels.



Warty growths on the foot typical of the infection, here seen in a male chaffinch

Whilst the outcome of the disease on individuals is still largely unclear it is thought that in severe cases birds die through incapacitation of the disease after loss of condition. Birds with this disease are also thought to be more susceptible to other secondary infections. Currently not enough is known about the way or efficiency in which the disease spreads but the fact that it occurs in clusters is suggestive that it spreads between individuals coming into contact with an infected bird. As with more serious diseases like Trichomoniasis and Salmonellois maintaining good levels of hygiene such as regular cleaning of feeders may help reduce the impacts of the disease on the local population.

Rain, Rain & more Rain

We have certainly seen a lot of rain in recent days in what is now a very wet North Yorkshire and has been for much of the year. It is very difficult to summarise the magnitude of winter rain and mild weather on our wildlife due to the number of adaptations different species have to cope with it. As with summer rain there are undoubtedly winners and losers. Waders for example like the curlew (below) must surely benefit from the increase in mud and access to soil dwelling invertebrates, which would otherwise be scarce or hard to get at in frozen or dry soils, this may also mean there is less need to expend energy moving around the country to match suitable ground conditions.

Curlew - Like other waders enjoy a bit of damp soil

 

However localised flooding is a very real threat to small mammal populations, hibernating amphibians and invertebrates. Small mammals like field vole suffer high mortality in wet weather, especially when the areas of prime low-lying floodplain become inundated with water. This habitat tends to contain very high densities of the species. However by their very nature they are ephemeral often chaotic populations which fluctuate dramatically even without high rainfall and flooding. They have the ability to rapidly re-colonise areas due to their quick breeding rates. Perhaps it is animals which hibernate which suffer the most from mild wet winters as hibernacula are at risk of flooding and the animals themselves frequently awake during warm spells which raises metabolisms and used fat which cannot be sufficiently replenished if a cold snap occurs. Fortunately most individuals are quite specific as to where they hibernate and often avoid areas prone to extensive flooding. Prolonged cold weather in many cases is probably more beneficial to many species.

Perhaps warmer wetter winters may even begin to alter the communities of fauna and flora which we see. Mild damp weather undoubtedly increases fungal communities which may in turn impact on hibernating amphibians and invertebrates, like this queen wasp (below). Even within species groups like bats we can see how different approaches may benefit certain species or others due to their life histories. Take the common pipistrelle bat for example, a highly successful species which is too small to successfully put on enough fat to survive full winter hibernation. Instead it adopts a strategy where it hibernates in less stable conditions compared to many other bats i.e. Myotis. This enables it to quickly react and forage in mild winter weather, perhaps this strategy is likely to further benefit from the weather we are seeing at the moment this year.    

Hibernating Queen Dolichovespula media - A recent addition to Yorkshires fauna

 

A mixture of weather is probably the ideal climate for many species, with limited amounts of extremes. I am a firm believer that evolution has adapted these species to cope and persist through extremes and even 2012 has probably not been as catastrophic as many feared during the summer. Perhaps only 2013 will reveal just how much the wet summer and winter floods have had on the regions wildlife for good and bad.

A Winter Frog

December is perhaps not the best time of year to view common frogs in North Yorkshire, however whilst watching a couple of sparrowhawks over the back of the house I noticed movement across the lawn. It was in fact a large female common frog, which appeared to be in good health, on a mission to cross the garden. It is more than likely that she was pushed out of her hibernacula by a localised seepage or flood, with the weather forecast frost free for the next couple of days, she will hopefully seek somewhere better for the remaining months of winter. Female common frogs (and immature animals) unlike many males hibernate terrestrially out of water. They tend to chose small mammal burrows, decaying logs, rubble piles, compost heaps and any other frost free, stable holes or gaps not prone to flooding (i.e. on features like embankments). Although it's not unusual to have breeding frogs as early as December in the south west, it is unusual to see them active here in December. Undoubtedly a result of the mild winter so far. Common frogs like other amphibians do not hibernate in the same way as we see with hedgehogs and dormice but simply take refuge and reduce activity levels. Being cold blooded means they do not have the same energy requirements and need to keep a warm core as mammals nor do they need quite as much fat reserves. In mild winters activity can be almost constant in some individuals, with refuge sought only during snow and ice. Common frogs have even been found with prey remains in their stomach during the winter, indicative of foraging behaviour. Unfortunately the rain was so persistent I could not get a photograph, but still an interesting record.   

The Lords of Carrion

Perhaps the best way to demonstrate how marvel can be found throughout the natural world is to look at one particular species of animal that has throughout history been a symbol of pestilence, across the globe. It is seen by many as a species which spoils foods, spreads diseases and eats the dead. On top of this its habit of feeding on its own vomit hardly endears it any further, with its long list of adversaries. I introduce to you the bluebottle, the true lords of carrion.

Female Calliphora vicina

But are bluebottles simply misunderstood? Having recently taken the dive and bought a macro-lens, I have had chance to take a closer look at the intricacies of these unpopular but interesting creatures. Bluebottles belong to the Calliphoridae family of flies which also includes greenbottles. In winter it is relatively easy to find adult Calliphora vicina basking on tree trunks and walls, in many cases a spell of warm weather has caused the animal to come out of diapause. This multi-generation species is likely to overwinter in whatever life stage (larvae, pupae, oradult) it is in with the onset of winter. The use of diapause for overwintering in this species shows a north/south divide, with southern populations tending not to go into hibernation.

The association of carrion and bluebottles is well known but perhaps the efficiency and importance of this relationship is not. Bluebottles are capable of finding a carcase over 6km away, which is quite impressive given their size. Carcases are detected by odour, with the antenna (see below) and have a preference for slightly decayed flesh, of larger animals in full sunlight. They do not necessarily choose potent smelling carcases like fish and prefer mammals and birds. In fact carcases are mainly used as a place to lay eggs in which maggots can develop. This is an important characteristic of the species, without it we would be knee deep in dead bodies and disease, which the flies do a very good job of removing.

Female Calliphora vicina

Adults feed on sugar rich foods for energy like aphid honeydew and more familiarly foods like jam and chocolate, they are undoubtedly important pollinators too, feeding on nectar. The other food eaten is protein, especially so in females (for egg development),  in the form of pollen, dung and carrion. In the photo above the intricate feeding apparatus can be seen (at the base of the head). This consists of a proboscis evolved for vomiting and lapping.  This has lead to the curious habit of vomiting stomach acid onto the food, to dissolve it externally, before feeding on it. This liquefied food passes up two channels through two broad lobes (seen at the base of the head, eitherside of the hair proboscis) into the mouth. So the whole vomiting behaviour have evolved because the bluebottle cannot chew its food.  

Certainly a charismatic species group and one who's value is perhaps unappreciated. A group which will hopefully be cropping up on here time for time.            

"In all things of nature there is something of the marvellous"

It was Aristotle the ancient Greek philosopher who said  "In all things of nature there is something of the marvellous" and how relevant those words are to my own perceptions and ideology of the natural world. As somebody who is a lifelong naturalist I have always had a fascination with the many elements of flora and fauna in the British Isles. I have always tried to maintain a generalists approach, despite the draws and perks of specialisation. Having lived in Yorkshire all of my life I have a particular fondness for the county and its wildlife, which is as varied as its weather; from its lowland chalk meadows to its raised acid bogs the diversity of species and habitats must be one of the best in Britain. Not content with studying natural history in my spare time, I decided to embark on a career as an ecologist and hopefully put some of the enjoyment I get from the natural world back into it through conservation. The combination of these factors as well as a recent growing interest in wildlife photography has pushed me into blogging. Blogging is not only a fantastic way of maintaining my personal records and experiences but it also allows the engagement of likeminded people.