Jewels on the Wing

I have been collecting data on the wildlife of 'my patch' for over 15 years now and its about time I did a little more with that information.

At this time of year we are approaching the end of the Banded Demoiselle flight period and so I thought it appropriate to explore their population dynamics since 2003.

How has their population size changed over time? Has the time they first emerge got earlier or has the length of their flight period changed. I can answer all these questions in a series of graphs.

Graph 1 - Number of maximum individuals recorded each week

This graph shows that between 2003 and 2013 the population was fairly static at less that 150 individuals in flight er observation. This increases markedly in 2014 with number rarely dropping below 200.

Graph 2 Date of First Emergence

Over the 16 years of study there is very little change in the week number in which the first Banded Demoiselle is seen. The trendline does indicate a very small trend for slightly earlier emergence times but is unlikely to be significant.

Graph 3 Length of Flight Period

Whilst emergence maybe getting ever so slightly earlier the duration of their flight period has remained static at approximately 15 weeks (11-20) although it could be said that this has only become more stable since 2013 with the variance in data becoming less than preceding years.

Graph 4 Maximum Emergence

This last graph partners with the first to take a more in depth look at the change in population, Here the maxima count values for each year are plotted highlighting the rising curve.

So what does all this mean? Well we can say that the population of Banded Demoiselles at the Saxon Mill is stable and actually increasing year on year within the same defined flight period. These sort of studies are very useful at looking at patterns but only go so far. We need some other level of data to explain the changes. Is the increase in numbers due to a change in sex ratio, better food availability or a reduction in predators. This opens up new avenues for investigation, I am reluctant to introduce the spectre of global warming but it is in temperature dependent species such as damselflies that its effects can be noticed.

You have to be careful in analysing data as well. You need to know about the ecology of the species, Banded Demoiselles spend two years as larvae before emerging therefore the population increase seen starting from 2013 reflects an increase in eggs laid in 2011.

The Missing Lynx by Ross Barnett

I rarely get chance to read wildlife books but I always manage to get through at least over the summer and this year I chose The Missing Lynx by Ross Barnett. It was recommended to me in the BBC Wildlife magazine and seemed to fit my current view on the current direction ecology and conservation needs to take in the modern world.

The book looks like it is about the proposed reintroduction of Lynx to the UK but this is misleading, as the byline states this is about all our missing mammals. For me, as a child whilst dinosaurs were interesting it was the mega fauna of the Pleistocene that were more fascinating. When writing a book on the natural history of Warwick I read through the records of Aurochs and Mammoth that once roamed on the same landscape I call my home.

Ross takes a balanced and light look at the range of fauna that once lived in Britain. He devotes chapters to key groups such as Hyena, Bears, Sabre-tooths and so on. He delivers the material with charm balancing the science of how we know with humour and flair. 

As a scientist himself who works in the field of genetic analysis Ross' expertise shines through and he explains fascinating details of evolutionary theory, likewise he places these animals in an ecological context with skill.

He invokes a real melancholy in his writing for what we have lost. His passion for these past creatures is palpable. He accounts for each species disappearance and doesn't shy away from laying the blame at our (mankinds) door. You may think that this would make the book depressing but his final chapter on the future of these mammals whilst still lamenting their loss highlights the positive actions that can be taken.

Ross explains the success of wolf reintroduction's in America and in Europe and how the beaver reintroduction in Scotland is a flagship for positive conservation action he also makes a clear case for Lynx reintroduction.

This books is for anyone interested in how our landscape was so very different from today or sees the potential for rewilding and reintroduction as key conservation policy for the future in the UK.

The book is available from all good bookshops.

Rabbits

Rabbits are a species in Britain that can often be overlooked. They are a common site across much of the country but their fortunes have risen and fallen considerably over the generations.

Its is believed the Rabbit that we know and love today was introduced to Britain by the Normans although the fossil record indicates that they had been present in prehistoric times but gone by the Neolithic. The Normans farmed them for fur and meat with warreners being appointed to look after the rabbit warrens.

The Rabbit is a survivalist and can thrive in a range of habitats as long as there is sufficient grass to eat and soil to burrow in to. Rabbits also have the ability to breed prolifically, the breeding season can be as long as from January to August and can produce a litter of between 3 and 7 kittens every 30 days. This amazing reproductive rate is important because lots of things love to eat them, they form the main diets of foxes, stoats and buzzards.

Such productivity brings them into conflict with farmers. In the 1950's in an effort to control rabbit numbers in Australia the myxoma virus was introduced to wild populations. This horrible disease internal bleeding and lesions on the eyes that blind them. Britain became infected in 1953 from France and began to devastate populations.

In the mid-1980's I remember you couldn't go anywhere in Warwickshire without stumbling over Rabbits, they positively filled the hedgerows and trackways. Then a contagion of myxamatosis whittled the numbers down to what we see today. Whilst the virus isn't a prevalent anymore outbreaks do occur and they are at risk from Rabbit Haemorrhagic Disease.

I took the pictures of the rabbits this weekend at Priory Park, here a stable population exists in the centre of town, multiple warrens are scattered across the parkland. Beloved by dog walkers the rabbits seem to have become accustomed to them and each year at this time it is possible to get quite close to the young rabbits.

They are obviously quite wary but on my bike they seemed less concerned and I was able to approach within a few feet. I was then able to observe them as the grazed on tender grass shoots. It was fascinating to watch the ears twitching. Twitching ears and noses are a common habit of rabbits but it was interesting to watch how they swivelled. As they turned their backs on me to eat their ears would turn round to keep fixed on me, listening for the slightest sound of movement.