Sunday, 23 April 2017

A Hunting Heron - Voles and Fish

Over the past several years I have been fortunate to see Grey Heron on many occasions. I have monitored a colony in Warwick and often see them at St. Nicholas Park and on my patch.

This morning I watched an individual Heron for some time as it hunted on the mill pond at the Saxon Mill. I watched as it stood stock still waiting for prey. It dived forward several times and failed each time, it got me thinking about what the Herons success rate was.
As I continued to watch a marveled at how controlled and stealthy such a large bird is. It places its feet carefully and lifts them to minimise splashes. It turns its head carefully watching multiple angles and once it detects a prey moves into position to start foraging.

The heron moved from the reeded central area where it was being unsuccessful to the bank side where over hanging trees might have improved visibility.

Whilst fishing here it saw something in the rocks on the bank side and quickly darted in to grab what seemed to be a vole. In the following sequence of photos you can see that it grabbed it with the tip of its beak and then rather than swallowing immediately it took it to the water and dipped it into the river. I do not think this was to drown the prey as it was too short a time but could have made swallowing easier as straight after it gulped the vole down.

The Heron grabs the vole side on from the rocks to the left

The Heron re-orientates the vole by gripping it by the head and neck
The Heron then dips the vole into the river
The Heron the swallows the vole whole, note the bulge in the neck as it passes down the crop.

Following this meal the Heron moved out of site under some low hanging branches. Here it spent 5 or 6 minutes before a splash could be heard and it emerged on the bank carrying a substantially sized Perch. Again the Heron did not immediately swallow its prey. Instead it moved swiftly away from the bank side and quickly flew across the river to thicker reeds where it then ate the fish. It was likely worried that another predator would try and steal his food and so relocated to better cover in order to keep it.


Interested by the herons feeding habits I found a paper in Bird Study which looked at how successful herons could be. The article indicated a basic frequency of prey at 1 per 55 mins with a 50% success rate.

I reckon I watched the heron for about 20 minutes and estimated it also to have a 50% success rate but a frequency of 1 per 12.5 mins.


Sunday, 16 April 2017

Bushnell Aggressor Trophy Cam HD Review

Only strangers to this blog will not know of my long-term camera trapping study. As of tomorrow, it will enter its 4th year of continuous operation. To start this I decided to upgrade the camera I have been using as my main camera. In the past year, I have experimented with Acorn models and whilst I have been impressed by them I opted once more for a Bushnell as my main camera. I did this mainly because I have been so impressed by the long-term stability that Bushnell has offered in the past.

My older Bushnell Trophy Cam ran 24 hours a day 7 days a week for 3 years with very few problems. I decided to upgrade for two reasons:

1. I wanted ti to improve the image quality I am getting

2. I was starting to get a concurrent error in which the camera would multiple trigger resulting in large volumes of clips to go through,

After a little research, I opted for the Bushnell Aggressor Trophy HD that I purchased from NHBS

Features

F2.8 Lens with a 38 degree of field of view
IR- Flash
Display Screen
SDHC Card
Hyper PIR
0.25s Photo response time
1s Video response time
Powered by 8 AA batteries

So how does it respond? well, so far I m impressed. It has been out for 6 days and the footage is clear. I have two clips to show this.
video


video

As I continue to use the camera I will continue to comment, especially as I think the field of view is different and I will need to reposition the camera to get the best footage.

Data collected over the past three years will be analysed and the results filtered into the blog as and when I finish it.


Monday, 10 April 2017

A new species for my patch

Whilst out for drinks on Friday evening the first thing I spotted as I took my seat beside the mill pond was a species of bird I had never seen at the Saxon Mill before - a Little Egret.


This small heron is becoming increasingly common in the UK. I can remember being amazed at seeing them on the Hayle Estuary in the mid-1990's when they were a national rarity today they are a breeding species found across the country, They often nest alongside Herons in colonies. I have seen them before at Warwick Castle Park and also at Aylesford School but this was first for the mill.

They are elegant birds with startlingly golden yellow feet. I took this on Saturday when the bird was still present, it was gone by Sunday.

Sunday, 2 April 2017

A Teal at Last

Today I finally got a good shot of a teal. I am a little surprised that a pair of drake Teal are still present on the river but today the lighting was good and I was able to gain their trust.

I spotted the Teal some distance away, luckily it was on the other bankside allowing me to get closer to it. It is remarkable how such a striking bird can be so hard to see. Just look at the picture below, how long does it take you to spot the Teal.



As I approached I could see that he was aware of me and was preparing to fly. I paused and sat on the bank. I avoided looking directly at him, such direct eye contact can spook birds and animals. I sat for a good five minutes keeping him in my peripheral vision. Eventually, he settled down and then began to feed, finally, it moved out of cover and allowed me to get the shots I wanted. It's a reminder that wildlife is just as much about patience as it is about luck and skill.


As I left I noticed a pair of Buzzards, one had been about all morning but a second had now appeared and the two began to circle. I saw them swoop together and wondered if it was a mating ritual, however, on a second pass it seemed more aggressive. I got a quick shot off and noted that one of the individuals moved off quickly following the final pass, a piece of behaviour called 'taloning' where an approaching Buzzard will reach out with its legs and talons and the other will turn and flip to bear its own talons.



In raptor's this is often used in food passing where one adult will pass food to another often a male to a female either as a courtship gift or a to feed a nesting female.

In other news, expect updates on two areas. Its the time of year for nesting and I have preliminary survey information on breeding swans in the area. At the moment I have located 3 nests but more news in a separate post soon.

The second news is in relation to my camera trapping. The main camera has been operating for three years and I have just purchased an upgrade for it. When it arrives I will do a review. Secondly, I have abandoned river cam. It's had some success but is limited. I have found a burrow with interesting promise and I have relocated that camera there. More information soon about who is living there.

Saturday, 18 March 2017

Badgers

It has been a long time since my last post. This has been due to a sudden increase in work, my Masters coursework has kicked in and I am also doing some research for the County Council.

Nevertheless I have still been collecting and analysing my camera trap data. This year the badgers seem to be more active than last year and again my theory seems to be holding up that there is a peak in active when the cubs are born underground in January/February.

Below is a short clip which exemplifies the badgers sense of smell. Badgers have very poor eyesight and rely on hearing and smell. In previous videos I have indicated the way the badgers forage through the undergrowth, in this case you can see the badger raising its head to catch scents on the air.


video

The graphs below show the change in patterns of prescence and absence over nearly three years.

2014-15

2015-16

2016-17

Sunday, 22 January 2017

River Cam make a short but auspicious start

Following repeated failures with Otter Cam I decided that for 2017 I would focus less on the target and more upon the place, so was born River cam.

I have managed to find a suitable tree upon which to place the camera, it has a view of a quiet part of the river close to a used entry/exit point. I have tried to aim it so that it picks up the near bank and the river. Since it was set up at the start of the year I have worked on the angle of view and so far captured little except a fox and some inquisitive fishermen who stopped to say hello.

This week something interesting was captured just a few seconds of a grey heron.

video


On the main camera the number of Fox sightings has increased I am still seeing the limping fox but the uninjured one is becoming much more regularly sighted.
An interesting clip invloves the Badgers though. It shows something obviously spooking a Badger and it high-tailing it out of there. Badgers have poor eyesight but excellent smell and hearing. You can see the Badger mark the territory and then detect something. It raises its head to get a better sense of what was out there before turning and running. It runs in the opposite direction of the sett.

video


As today was a nice frosty sunny morning there were quite a lot birds about. There were flocks of Black Headed Gulls and Redwings on the fields and there were plenty of small Tits in the trees.

A male Kestrel was out hunting which was nice and I managed to get a few shots.




As I was preparing to leave I saw my recent holy grail a lone male Teal. I managed to get some shots off at a long distance, but as always when I moved down the bank side nearer it disappeared into the reeds. Even so they are handsome birds and a pleasure to see.



Sunday, 1 January 2017

Camera Trapping - A review of the year.

My camera trap year runs from April to April but I thought people might be interested in some data from the last 12 calendar months.

In the past 365 my camera has been in place and recording for 335 days (92% of the year). It was activated a total of 3588 times of which 1052 were activation only's, errors or failures (29.3%).

This number of activations equates to 107,640 seconds worth of footage, that's 29.9 hours of clips to watch.

335 days equals 8040 hours and an activation by something recordable occurred 21.13 hours worth of time meaning that along the hedgerow there was an animal or me present 0.26% of the time!

The very first animal recorded in 2016 was a Wood Mouse and the very last a muntjac and fawn. They were recorded at 23.58 on the 31st December. This goes to prove that Muntjac will breed throughout the year.

video

Aside from myself over the past, 12 months's the camera recorded:

Wood Mice - 255 activations
Muntjac - 233 activations
Badgers - 246 activations
Foxes - 133 activations
Grey Squirrels - 312 activations
Rabbits
Brown Rats
A Domestic Cat

Wood Pigeon
Blackbirds
Song Thrush
Robin
Dunnock
Great Tit
Wren
Magpie
Pheasant
Moorhen
Jay
Redwing



The pie chart shows that the occurrence of the main species is fairly even although Grey Squirrel just edge the most populous and the Red Fox is the least.

Over the year I have caught some interesting behaviour such as identifying the badgers regular sprainting and how they forage. The squirrels have been very feisty and squabbling a lot and the fox has been quite elusive.

On the unusual side has been the few sightings of Rabbit. Rabbits used to be prolific on the site but never recorded on the camera using the hedgerow but this time over a few days individuals were sighted, possibly bucks seeking new territories.

Heres to another 12 months. I will have completed 3 years worth of data and so look out for graphs of each of the main species then.