Thursday, 25 June 2020

It's all about mass

With all the good weather recently I have found myself often sheltering from the heat in the shade beside the water at the Saxon Mill. From the terrace there are several spots where you can sit comfortably and look out over the mill pond and into the murky water to watch the fish.

Look carefully enough and you can see a pike


Today was one such occasion. We are experiencing a mini heat wave, by 10 am it was already 24 degrees C in the shade, and out in the open heading for 30! I had gone down the mill to exchange the batteries and memory cards on my trail cams, and to leave some peanuts out for the badgers, in hot weather like this they struggle to dig up earthworms. On my way back I stopped at the mill pond and looked to see what fish I could see.

I was lucky enough in late may to catch sight of a pike hunting the shoals of roach. I had heard that they were common on this patch. They lurk on the river bed beneath the lily pads and wait for fish swept through the mill race and then strike. It was amazing to watch.

Today there were no pike hunting nor did there seem to be many roach of any significant size. Instead I was mesmerised by the mass of smaller fish, fry, shoaling beneath me. The shoal perhaps number 300 individuals and it moved with one mind, just like you see in the wildlife documentaries. Occasionally you saw a flash of silver as one fish twisted to one side and signalled a change in position. As I watched them, they seemed to be doing circuits of the lily pads a though struck me.

Here were around 300 young fish in just a very small stretch of water. Even if you discounted the deeper parts of the mill pond there were enough shallows to estimate that this particular section only represented one one hundredth of the available habitat and this would be an underestimation. This then would mean potential for 30,000 young fish striving to make it to adulthood and bear in mind that this is only a tiny fraction of the number of fertilised eggs that survived to hatch.

Where do all these little fish go? They certainly don't all become big fish, 30,000 fish appearing in the river each year would soon be noticeable and fishing as a 'sport' would be come redundant a literal shooting fish in the barrel. Predators are all over the place winnowing out the weak and unwary and of course there is disease or injury. Grey Herons and Kingfisher are common right along this stretch of the river and as I have already mentioned pike are abundant. Regular readers of this blog will know that Otters are on the increase in the river although I doubt they would bother themselves with the tiny fry I was watching.

When I talk about mass, I am referring to biomass, the net weight of biological material. During the summer this mass is evident in the number of leaves on a tree, the rapid growth of the vegetation and all the insects upon which this fry and fish will feed upon. We are mid-way through the Banded Agrion flight period at the moment. In last years flight period I recorded a total of nearly 800 individuals during my weekly 1 hour visits. Again this is only a tiny proportion of those that survived the egg and nymph stages and a tiny proportion of all those that took wing that season.

I think it speaks well of the health of the Avon in Warwick that we see such good numbers. They represent a link in all those important food chains and food webs that tangle and weave their way around the ecosystem. It also highlights the losses incurred by species. Think of all the eggs laid by some insect or fish species only for one or two to make it to adulthood. This is what we ecologists call R-strategy.

R-strategists produce masses of low cost offspring that they 'know' will struggle to survive. They take the machine gun approach to life, if you fire enough shots you're more likely to hit the target. The converse of this, something that most mammals do, is the K-strategy. Here you invest all your energy into a few offspring but you make darned sure they make it to adulthood, by feeding them, teaching them and protecting them. These a more akin to the skillful sniper. They take measured calculated shots that increase the chance of hitting the target.

Back to the fry, they are one component in a vast array of interconnections and complexity, they feed on the invertebrates in the water who in turn have fed on each other and the aquatic vegetation. They in turn are food for the predatory fish and birds, who are in turn prey for something else. Its only when you start to piece this intricate patterns together that you can begin to understand the fragility of some systems. Ecology is elaborate, intricate, delicate and profligate it is why I hold it so dear and champion it as the science of kings.

Sunday, 21 June 2020

Swallows on the Avon

Today on my Sunday morning survey I was lucky enough to spot some young swallows down by the willow. Each year swallows frequent the fields around the mill, it is amazing to watch them as the swoop low over the corn and zip around the trees and on occasion around me hawking for flying insects.

So far the number of swallows this year had seemed low and I was unsure of how successful their breeding would be. There are a range of farm buildings at the top of the hill where they nest. Swallow numbers have gradually declined since 2011 although they still remain healthy as a population.

This year I first saw a swallow on the 17th May which is on average 3 weeks later than in previous years. This is no doubt due to bad weather in the Mediterranean during early April. Such long distance migrants are susceptible to adverse weather conditions, in this case high winds caused the death of many (https://www.theguardian.com/environment/2020/apr/10/high-winds-kill-thousands-of-migrating-birds-in-disaster-over-greece)


Three young swallows were perched in a willow beside the river, usually the sit in the isolated hawthorn in the field or in one of the tall dead alders. Here they were well protected by the vegetation. You can see that this individual did not fledge too long ago. It still has fluffy down on the chest and there is significant colour surround the beak wear the gape remains.

The adults hunted across the fields and along the river but only seemed to feed the left most individual perhaps because he was more accessible. Eventually the juveniles moved of to practice flying and one of the males stopped for a perch. This is a lucky shot, away from the nest sites and on wires when the are gathering to migrate south it is uncommon to see adults settled.


Here you can see the bold red chin and mask and really see the long wings and streamer tails. They are such slight and elegant birds it amazing that they have the stamina to fly such vast distances each year.

Saturday, 23 May 2020

Badger Hygiene

With lock down in full force I have had extra time to spend on my patch of land. I have moved one of my cameras to look at the nearby Badger sett.

I am pleased to say that it seems they have had two cubs this year,



There are at least 3 adults.


One of the more interesting aspects of behaviour observed is that of cleaning, especially apt at this time of hygiene awareness.

Badgers are well known for keeping a tidy home, they will replace bedding regularly and ensure they use communal latrine pits well away from the sett.

Personally they love nothing more than a good scratch. In a group setting a clan of badgers will reinforce relationships with mutual grooming in this case however this is a solo effort.

The following video shows a single badger, possibly a female, scratching for a good minute and a half,




The grooming shown is clearly not to make the fur smarter as the badger is incredibly dusty when it finishes, it is in fact entirely focused on removing unwanted guests on the skin and in the fur.

Badgers like all mammals suffer from a range of parasites chief among which are Biting Lice (Trichodectes melis), these are not normally a problem unless the individual is ill or weakened. Badgers are also prone to fleas, Paraceras melis, and hedgehog and mole flea species. The last major parasite is the Tick, these are common in all mammals and are normally sheep ticks although in this case the lack of sheep in the area is likely to mean any ticks in this clan come from deer.

As you can see the scratching is quite thorough and the individual seems to enjoy it. We all love a good scratch after all.


Monday, 23 March 2020

Atlas of Britain and Ireland's Larger Moths - Book Review

This month saw the publication of the long awaited Atlas of Britain and Ireland's Larger Moths. This mighty tome is published by Pisces  The publications is curated by a range of top entomologists and supported by all the local record centres and county recorders, produced by Butterfly Conservation and Moths Ireland.



The atlas contains a detailed account of the recording, analysis and layout of the distribution maps and trends. The results are complex and look at species richness and long-term distribution and abundance trends. These is an extensive section on causes of distribution changes and of conservation measures.

The species accounts cover every major larger moth species, this amounts to 893 species. Each have a colour photo of the moth in question and a graphic of the flight period.
The maps cover all of the UK and Ireland and clearly shows three levels of temporal information, pre-1970s, 1970-1999 and 2000 on wards. This enables the reader to identify distribution and range ranges over the last fifty years.


I have bought this volume to aid in my growing foray into Moth recording. Alongside identification guides it gives a useful perspective on the distribution and rarity of the species I am likely to discover.

The writing style is functional and informative and the layout excellent. The maps are clear and the photographs are exceptional. The paper quality is is strong gloss, bringing clarity to the images and longevity. The book is hard back with solid quality binding.

This is a first rate publication for any nature lover.

Priced at £38.50 it is available from all good book shops.

Saturday, 21 March 2020

Antlers on the bridge

I have recently purchased a new brand of wildlife trail camera. I usually use Bushnell exclusive and have a couple of Ltl Acorns but decided to try out the Browning. There is a fallen tree across a brook that has silted up creating a little bridge across for all sorts of animals to use. I decided to place the camera here to look at the passage of mammals and get a better look at individuals that use the area.

The number of Roe Deer sightings have increased in the past year or so and there seems to be a small herd of perhaps 4 individuals. I have caught fleeting glimpses of these deer in the distance, they always see me before I see them and move away quickly in typical bounding gait flashing their white rumps at me.

Last year I identified a pregnant female and later a fawn and so I know that the breed in the area. With this new camera I m starting to get an idea of the population. In the clip below we have a fine example of a Roe Deer buck.



The individual seen appears to be a buck in his prime. He has a set of fine antlers which you can see have the standard 3 points and is still covered in velvet.

Roe Deer are generally solitary but form small groups in the winter and the Buck is accompanied by a smaller buck whose antlers only have one point, one of which is strangely longer than the other.


In future weeks I hope to bring you some shots of Roe Deer does as a comparison. Whilst the does are probably still in a group at the moment the eggs that were fertilised in the rut in July/August will have implanted in January. This means the females are likely pregnant in May/June.

Saturday, 15 February 2020

Whats a mostela?

Over Christmas and after the exciting sightings of weasels on my site I decided I had to improve my understanding of the various smaller mustelids that were present on my site.



Weasel crop up occasionally and an in April 2015 I observed two Stoat playing in the undergrowth bit nothing since. In recent years Otters have been more evident with the latest record being just the end of the tail captured by my trail cam last month and in January 2015 saw a single shot of a disappearing Polecat. There are of course my resident Badgers who continue to do well. Mink seem to be very much on the decline, I haven't seen one in years but their footprints are still evident.

I began to look through the web at ideas of how to improve my understanding of these species. The large mustelids are pretty simple, they show up on my main camera trap quite well  but weasels tend to move so fast that good images are hard to get. In my research I came across some information on the Vincent Wildlife Trust about their work using a Mostela to look at weasels, stoats and small mammals (Vincent Wildlife Blog).

The mostela is a Dutch invention designed by Jeroen Mos of the Dutch Small Mustelid Foundation. I read through this wealth of information and downloaded the specifications for this intriguing device.
A mostela is essentially a box with a guttering pipe entrance in which a camera trap is placed. Details of the design can be found here: Design.

From the plans I ordered some marine plywood from WoodSheets, they are a bit pricey but they cut the wood to shape and delivered. I ordered a section of guttering, hinges and clasps. I put it all together but didn't make as much of the interior, leaving the camera free.




Next came siting the mostela. I took it down last weekend and put it in place, setting the camera and covering it in leaves.
I came back this weekend to swap out the camera card and see what I had got.

Whilst I didn't get any weasels or stoats I did get another of the sites under recorded species - the Common Shrew. I hear these regularly in the summer but rarely see them but these curious mammals certainly had a look around. A single shrew visited on three separate nights.Wood Mice also visited on three nights and during the day it recorded a nosey Wren snooping about. (Ignore the date stamp I foolishly set it to 2019 and not 2020).





This is all good news as it looks as if it will help monitor the other small mammals, I m interested if it will pick up the vole species I know are present but this might mean relocation, which is difficult given the recent storms as there are few places I could leave the mostela where it wouldn't get swept away by rising flood water. The rodent and insectivore visits are good news as well because their scent trail should encourage the other predator species to investigate.

I plan to move the mostela about every few weeks and will leave it unbaited. I need to check camera positioning and focus but for the time being I am pleased with results. I will keep you all posted on what I find.

Tuesday, 3 December 2019

Weasels abound

Over the last month I have seen an increase in Weasel sightings on my trail cam. I know weasels frequent the site as do all the other mustelids, I have records of badger, otter, stoat, mink and polecat, but there is something about the weasel. The badger will always be my favourite animal but there is something about the character of this tenacious beast that interests me.

It always surprises me how small weasels are, between 175 and 248 cm and they can move like lightening. Due to their frenetic foraging pace getting a photo of a weasel is difficult. I stumbled upon one in 2014 which hid in a tiny hole in the trees and managed to get a few shots as he watched and waited for me to leave.

Mostly diurnal their daily activity occurs in periods of 12-130 minutes. Its high metabolism and hunting style means that it must eat up to a third of its body weight a day. Foraging is usually done undercover and quickly presenting two problems for camera trapping. In fact reviewing my records shows that all sightings have been in September and November or March April.


The first clip shows the weasel in the bottom right moving out of shot and then running back around the field of view.

Earlier on the 7th November I got a good clip showing the Weasel climbing a tree, showing of its agility. Weasels are primarily predators of small mammals and this particular tree is a favourite of Wood Mouse who forage around it and themselves climb it. Interestingly the mice are never seen before it is fully dark so it is possible that the weasel is following a scent trail.


It might seem the weasel is adept at climbing but two days later on the 9th it had less success at climbing as captured in the third clip.


To finish with a statement about what this means. Recent sightings represent a significant increase of presence for this species. It suggests, that given weasels  foraging distance of between 549 and 840m often with preferred foraging areas within 100m of the den suggest that at least over this winter an individual has taken up residence. With the vegetation gone this means that further sightings maybe be made or this could be an individual dispersing through this area and will be gone soon. It will be interesting to see.

To finish I leave you with my picture taken back in 2014. Note the barbed wire to give you some sense of scale of this enigmatic creature.