OtterCam in October

I have had a camera in position most days in the first three weeks of this month, apart from when the water level was too high after heavy rain.  The limitations of trail cameras remain apparent.  On one occasion an otter, or possibly more than one, went past the camera heading north and left these tracks on the sluice without making a recording.  I think the reason is that a wet otter seen from behind and going away looks cold and has no heat signal to trigger the camera.

Taking photos of the tracks under the water was interesting.  I used a polarising filter to reduce the reflections and I think the camera just about managed to focus on the tracks rather than the surface.

Then some good news.  The mother with both pups left a brief recording.  They were too close, and out of focus, by the time the recording started, but at least we know they are alive and well.

As you can see on the video, one of the pups took a very close interest in the camera and turned it round so I had to reposition it the next day.  The rising water had also just reached the bottom of the camera so I got there in the nick of time.

Here is the trail camera so you can see it needs to be secure.  It is screwed onto the top of a coarse fishing bank stick. Thus far I haven't fallen in.

On another occasion a single otter went south and left a track including a tail drag.  This photo was taken with a small pocket camera with no filter.

The trail camera did pick this one up.  As it is alone and has no shoulder wound I assume it is a dog.  It also had a sniff at the camera.

Because of the persistently high water level I then moved the camera to another site and struck gold.  Here is the mother with her two pups, all looking fat and healthy, even though they still have their scars.  I had put out some sardines but by the time the otters turned up, at about 04.30, all the food had been eaten by rats.  The good thing is that I was able to set the camera back a bit to get them in focus and get all three in the frame.  A few frame grabs,

and then the video.  They even did their own editing for me.  This is one complete clip.

The next night the otters turned up early, not long after dark, to make sure they got the food first.  They stayed for about five minutes so I have shortened this video.  It was a wet and windy night with rain on the lens so the quality is not the best.

On the last two nights the camera picked up the mother otter on her own (as she was couple of times in the report two weeks ago) so I am not sure where the pups were.  Perhaps they had found something more interesting than sardines. Because of their scars it is now quite easy to identify the three individuals even when they are not together.

I'll put the cameras out again in a couple of weeks and report back here.

And another one

This was an exciting surprise.  After a series of several juvenile male sparrowhawks (see below) in the past three years, a beautiful adult male turned up.  At first I thought I wouldn't be able to get a photo, because although this window is normally set up as a hide, this time it was completely unprotected.  By moving very slowly I managed to get a camera into position without spooking him.

He sat for over a hour, sometimes on alert for the next kill and sometimes stretching and preening to show off all his feathers.

My friend Chris Wright, an expert ornithologist and bird ringer, says in theory this bird could be from last year (ie hatched in 2018) but after the first moult sparrowhawks retain a few feathers with (juvenile) buff tips, which are completely lacking here, suggesting it is at least two years old (ie hatched in 2017 or before).

This got me wondering if I had seen this bird before and if I could identify individuals from the last three years. Obviously feathers are no use because they are moulted and move around a lot as the bird moves but I noticed a brown mark on his cere.  The cere is the waxy-looking yellow covering over the base of the upper mandible, sometimes also known as the operculum.

Looking back through photos of previous birds, below is the first adult male from Jan 2017.  He has mottled brown and white marks on the cere.  (Most of the photos that follow were taken with only a 200mm lens and are therefore heavily cropped.)

Five week later the appearance was the same, so these were not just dirty marks.

This is the first juvenile, who appeared in December 2018.  His cere shows dimpled brown marks.

Two months later there was the same appearance, so it is the same bird and the marks persist, in the short term at least.

This was his last appearance at the end of March 2018.  I don't know if the marks are cause by injury, wear, nutritional deficiency or something else and so far I can't find any information about it.

This is the next juvenile on his first appearance in November 2018.  His cere appears a bit darkened and damaged or deformed in the centre.

In December it looked the same.

He was here until the end of March this year and was unchanged so it appears that these marks persist over a few months and can be used to identify an individual.  What I don't know is whether the cere would heal or regrow over a longer period.

The next sparrowhawk to turn up was a rather faded and scruffy-looking juvenile at the end of July.  He had several brown marks down the centre of the cere but also a bit of damage causing a transverse groove in the culmen, the ridge down the top of the upper mandible.  I originally assumed he was last winter's regular bird but I now think  I haven't seen him before (or since).

And this is the latest youngster, from September.  He has small brown marks on the left and across the front of the cere so now I know to look out for them I should be able to keep track of him.

All this means that if the marks persist long term the present male sparrowhawk isn't one of the previous four youngsters but is a bird I haven't seen before.  It also means I have had four different birds sitting on the perch in the last six months.  Here are all six from the last three years, all individually recognisable.

OtterCam - In the pipeline

There is a lot to learn for a young otter - how to catch fish, how to stay safe, how to get around the territory - which is why otter pups stay with their mother for over a year.  Otters often use man-made structures such as pipes, culverts and conduits as they travel around so this seemed a good place to set up the camera.  It was mounted on a support in the stream bed just outside the pipe and gave my first view of the female with her two new pups.  I think they were probably born around March and are about six months old.  In this still frame the mother is in the middle.  (The pipe is only 75cm [2' 6"] in diameter so you can see that otters are really quite small.)

The first time they encountered the camera the pups turned and ran, taking their mother with them.  I don't know if it was the sight of the camera or my scent that put them off but after that they got used to it, although they were still wary as they passed.  On the second part of this brief montage the family is heading north past the camera on the following night.

One limitation of a trail camera is that the animal has to be in the frame and the camera has to "see" the animal before it starts recording.  Add in the camera's reaction time (usually around half a second) and a fast-moving animal and the delay becomes quite noticeable.  The Browning cameras I use record clips of only 20s at night with a short delay in between and you can see that limitation on this next video as well.  At the start mother and one pup (pup 1) are already halfway along the pipe while the second pup (pup 2) is back on the sluice and doesn't make it over.  Mother obviously realised she was one pup short and went back while the camera wasn't recording.  There was a 16s gap and when it started recording again mother was just passing the camera again but pup 2 was very uncertain, worried either by the camera or the (2 inch!) drop at the end of the pipe.  It retreated a couple of times before creeping past.  If you listen carefully just before the end you can hear a little warble above the sound of the water which I think is the mother encouraging the pup (or the pup complaining to the mother).

You will notice that pup 2 appears to have an injury on its right rear leg, although it seems to be moving OK on the video.

There are also wounds on the mother's right shoulder and right rear leg.

After that I didn't see mother and pups for a few days but I did pick up a lone otter which was twice spooked by the camera and turned and ran.  As it did so I am pretty sure I can see it is a dog otter - and it has no injuries so is definitely not the mother.  It could be one of her previous pups.

On the next few nights I saw only the mother alone in the pipe and I feared the worst.  Her wounds are clearly visible and perhaps look like bite marks - there is also one on her left hip.  She found some Waitrose sardines in the pipe.  I wonder where they came from?

Then a couple of nights later I saw the family again.  On this montage pup 1 appears in front of the camera and turns and goes back.  Note that it now also has a right shoulder wound.  Seconds later mother passes the camera followed by pup 1 but pup 2 doesn't appear.  Realising that, they go back for it and you can hear pup 1 complain as it slips in the slippery pipe.  All three then run past the camera and pup 2 pauses to look at the camera.  I am not sure if it has a problem with its right back leg or if it also slips in the pipe.

I carried on monitoring the pipe and two nights later a large lone otter sniffed the camera before heading through.  I guess this is a male but it appears to have two scars on its left haunch (whereas the other male was unmarked) so I think it is a second male.  The water was already a lot deeper.

In retrospect I think the lone otter I saw at the start of September, a couple of days before this series started, was the dog otter that had no injuries.  I now think neither of the dog otters (assuming there are two) is the father of the pups and one of them, perhaps the larger scarred otter, is trying to kill them in the hope that female will produce his own offspring.  The family's injuries were probably sustained as the dog otter attacked and the mother defended the pups. (Female otters probably breed only twice in a lifetime and this is at least her second litter so she has a lot invested in them.)  Male and female otters meet only to mate and the pups are raised solely by the female.  Male territories are large and overlap several female territories but there are also yearlings in the population which have not yet established a territory.  We definitely have four otters and I suspect there are five, for now at least - one female, two pups and two males.

The image many people have of otters is of playful, furry friendly animals but the reality is that they are wild predators in a battle for survival and life can be very hard.  Although the prospects for otters as a species have improved in recent years, there are many challenges in life for an individual.

In the last couple of weeks I have lost track of the otters.  The persistent heavy rain has meant the the water levels have been very high making it difficult to find somewhere to position the camera and perhaps also changing the otters' routine (not that they have much of a routine).  I eventually managed to get a camera in again yesterday.  As soon as I find out what has been happening I'll post an update here.

Mothing beginnings

National Moth Day was held over three nights at the end of last month but in the end was a bit of a wash out.  I was all set to take part after Cain Scrimgeour and Heather-Louise Devey of Wild Intrigue kindly lent me a moth trap to try out in my garden.  In the end the weather wasn't good enough to put out the trap but I did give it a try on a dry night a few weeks earlier.  

Catching moths is the easy bit.  Identifying them is hard.  Dragonflies are manageable with around 45 UK species, butterflies are OK with fewer than 70, bees are difficult with around 275 species but then there are 2500 moth species in the UK.  I caught dozens of moths and I took lots of photos and borrowed a guide book and looked them up on a couple of websites but for an absolute beginner it is pretty intimidating and difficult to know where to start.  I had also booked on a workshop looking at moths with Cain and Heather but it was cancelled because of bad weather!

I was hoping to catch something exotic and colourful but all mine were grey and brown which is good for camouflage but doesn't make identifying then any easier.  Although they aren't all the same colour I think several of them the same species - Large Yellow Underwing (Noctua pronuba). 

I think these might be Dark Arches (Apamea monoglypha).

This might be a Common Carpet (Epirrhoe alternata).

This might be a Riband Wave (Idaea aversata).

To give you some idea here are some of the others I caught.

If I am to make anything of this I'll have to get or make my own trap and learn more about moths and get better at photographing them.  We'll see what happens.