Sparrowhawk news

This blog seems to have been taken over by mammals recently so here is an update on the sparrowhawks.  At least one of them is here almost every day, more often the juvenile.  I have never seen both in the garden at the same time but the two photos above were taken only 30 minutes apart.

I haven't witnessed many kills by this winter's juvenile male and although he watches the birds besieged in the gooseberries he doesn't often attack them.  He spends a fair amount of time posing and preening on the sparrowhawk perch and more often attacks and chases birds flying in to the feeder.  If he doesn't return immediately I can't tell if he was successful. 

Here he is preening.

And watching. 

Sometimes his visit is brief, perhaps because he catches something straight away or gets distracted chasing a bird out of the garden.  He also shows his inexperience.  Once I saw him climb into the gooseberry bush and have difficultly getting out without injury, during which time the dunnocks and tits in the bush had all escaped.  He then tried sitting lower down on the main perch, perhaps hoping to be less conspicuous.

Another time he was sat on top of the feeder, not a very subtle ambush.

This juvenile bird is a lot less predictable in where he sits than previous birds so I have to do a lot of checking before it is safe to go out.  If he is on the perch in the kitchen garden there is no problem but sometimes he is on top of the hedge, overlooking the front door.

When I come home I have to check before getting out of the car to see if it is safe to come in.  Here is a distant shot along the drive from the car at the gate.  I waited 20 minutes before he moved.  I must be crazy.

He also sits on the apple cordons against the fence,

or on top of the fence,

or on the gate into the kitchen garden.

I try not to disturb him but if he is in the trees outside the kitchen window there isn't much I can do as it is very hard to see him there before I go out.  To give the small birds a break I put up a feeder opposite the front door, very close to a yew tree to provide cover.  But the sparrowhawk soon spotted it and now he stakes that out as well.

I have seen less of the adult male but he still visits and is very handsome.

Here he is looking fierce.

He also spends time preening.

And sits on the hedge to stop me going out.

I am pretty sure a female bird visits occasionally as well.  I haven't seen her but have seen the remains of wood pigeon kills, which would generally be too big a target for a male bird.

WatervoleCam

This was a chance observation on a camera set to look for otters.  I noticed a small animal scurry across the bottom of the picture for a brief moment.  It is obviously a vole but is a bit out of focus and the freeze frame is blurred.  It is too close to the camera so it is not easy to judge its size.  On the other hand it is in water, and from where it went it would have to be a confident swimmer as it is some distance before it could get out again.  The vole wasn't in view at the start so I am not sure what triggered the camera (there is the intriguing possibility that it was following another one which moved out of view in the time it took for the camera to start recording).

On this freeze frame we can see its tail but it is blurred and curving away from the camera so it is hard to judge the length.

I was hoping this was a water vole so I sent the video to the Natural History Society of Northumbria who sent it on to Kirsty Pollard of the NE Water Vole Project based at Durham Wildlife Trust.  And Kirsty has confirmed it is a water vole. This is only the second sighting of a water vole in Gosforth Nature Reserve in recent years.

Because the video is so short I have added two slow motion replays so it is easier to see the vole.

My friend and fellow naturalist and photographer Chris Castling took a photo of a swimming water vole in Gosforth Nature Reserve last year, the first observation in the reserve for many years. You can see his photo here.  After Chris saw his water vole I tried for nine days and nights to catch one on a trail camera without success, so this latest finding was a real bonus.

This map, from the National Water Vole Database and Mapping Project shows the distribution of signs of water vole presence in 2006 - 2015.  The location of Gosforth Nature Reserve is shown by the red arrow and, although water voles were very rare in Northumberland, signs (green dots) were detected nearby on The Ouseburn, so it isn't all that surprising that they should still be around, even if rarely seen.

The water vole is Arvicola amphibius, sometimes also Arvicola terrestris.  Water voles were common when I was young but the population crashed to only 5% of its former level, mainly because of habitat loss and predation by American mink (Neovison vison), a non-native invasive species.  There was a 30% loss in 2006-2015 so the problem is continuing.  Protecting water voles involves improving habitat, controlling mink and, occasionally, reintroduction.  There is a reintroduction programme, Restoring Ratty, in Kielder Water and Forest Park (blue arrow on the map above) which you can read about here.  It is a five year project with 1500 voles released so far.  The hope is that they will spread down the North Tyne and link up with a population in South Northumberland.

OtterCam in January

This is my twelfth consecutive month of setting trail cameras to look for the otters and the eleventh month in which I have seen them.  I set the cameras near the water's edge one night and was very pleased to see three otters - the mother and her two pups - the first time I have picked them up since November.  They only appeared one at a time so it isn't easy to say which is which - the pups are probably now about nine months old, so nearly full grown.  I suspect the first to appear was the mother.

This otter has three marks or scars on the left shoulder.

The next one came out of the water in the same place about 10 seconds later.

This one has a single mark or scar on the left shoulder.

About 50 seconds later a third otter came out of the water in the same place.  As far as I can see this one has no marks.

All three otters went off to the left as this camera looks at it.  A second camera was looking in that direction but only the first otter triggered a recording, perhaps supporting my theory that a wet otter seen from behind has too small a heat signal to trigger the camera reliably.

Here are the three videos.  The otters often take an interest in the cameras.  The first one here gives it a sniff and leaves the lens steamed up and smeared.  Note there is a bit of spurious reflection of the light in the otter's eyes from the extra close-focus lens, giving the impression that there might be a second otter in the picture but that isn't the case.

As a result of the first otter wiping its nose on the lens the next video is rather blurred.

The lens still isn't back to normal by the time the third otter appears.

I have also had a camera set up to monitor the sluice gate and pipe for several nights this month.  On a few nights the camera picked up a single otter but I can't tell whether it is one of the three or a lone male.  My guess is that it is a large male.

Judging by the tracks the three otters haven't been that way recently.  The pipe and the sluice gate are both very slippery and the tracks show how the otter slips around.  The footprints wash away after a day or two and so are a good indication of recent activity.

On this video the otter runs through the pipe away from the camera.  It returned the next night but was almost up to the camera by the time recording started.  Like the other otter above, this one sniffs the camera and leaves a wet mark on the lens.

Another time after rain the water had risen more than I had anticipated and when I returned the bottom of the camera was in the water.  To my surprise the camera was OK and still worked and had continued to record.  Because the water level was higher the otter was wading rather than walking through the pipe.  On the first recording it was approaching the camera and ducked under the water when it saw it.

It returned two nights later during a gale and with the camera almost in the water, giving a very dramatic picture.

I have put these together on a short video, including a slow motion repeat of the first brief clip.  At the end of the second clip the otter turns and looks back at the camera suspiciously before disappearing over the gate.  You can see how close the camera was to the water but it makes for a good picture.

A male otter can take several days to go round its territory.  This one seems to be going through the pipe about once every two or three nights.  It is interesting that it is mostly going north (away from the camera), suggesting that it has a regular circuit to patrol.  This final montage is from earlier this week.  After the near miss with the water the week before I mounted the camera a bit higher on a bracket fixed to the pipe.  However, I prefer the pictures from the lower position.

The sluice gate is in the process of being raised so it is now more of a step up.  Soon it may be a bit too high to climb and he'll have to use another route.  Another sniff of the camera as he passes.

It is noticeable how the otters seem to have become used to the cameras.  I am sure they can see the infrared light on both the no glow and low glow cameras.  When the pups and the male(s) first came across the red glow in the summer they turned and ran but now they are just curious.  It is interesting also how often they sniff the camera.  Maybe they are just checking that it is me.

I have made a further refinement to the close-focus lens.  I cut down the Poundland reading glasses lens with a fine hacksaw to fit the camera and sealed it in with gaffer tape.  I hope this will prevent spurious reflections from the back of the lens and reduce the risk of fogging.  It seems to be working.

I think the otter pups were born around last April and they will probably stay with their mother for just over a year. These two are now noticeably more independent and don't trail their mother as closely as they did when I first saw them in early October.  I'll continue to monitor them to see what happens.  I think this is at least the mother's second litter and not all live long enough for a third.  If I am right about a lone male also being around in the territory I expect he has his eye on the situation as well.

FieldvoleCam

I have a new neighbour, recently moved in opposite my front door.  It is a field vole and has set up home at the base of an oak tree.  Over the last couple of weeks the holes and adjacent runways have become more noticeable with use and wear.

The field vole (Microtus agrestis) is identified by its greyish-brown colouring and short tail (its other name is short-tailed vole).  Bank voles (Myodes glareolus), which are common in my garden, are slightly smaller, reddish-brown, with a proportionately longer tail.

The field vole builds a system of holes and runways in grass.  This one is in the area that was meadow last year, and will be again this year, perhaps what attracted it.  I first tried my usual low-down camera position but it didn't work for a vole in a runway so I tried putting the camera on a tripod, angled down at about 45°.  Here you can see the vole dashing through the runway and holes as it collects sunflower seeds.

Here is another video recorded at night.  Like most animals and birds I have recorded with this camera, the vole seems unconcerned by the bright lights from the camera.

Here is a closer view of the vole collecting sunflower seeds.

Here it is collecting grass, probably to eat, possibly also for nest material.  Note its short tail.

There are half a dozen or so holes within an area of about half a metre square where the roots of a dead sycamore run across the base of a turkey oak.  The holes must all communicate with the nest inside and presumably allow an escape through a side door if a predator, such as a weasel, comes in through the front door.

Field voles have a lot to worry about.  They are the favoured prey of weasels, barn owls and kestrels and are also hunted by other owls, stoats, foxes, badgers, hen harriers, buzzards, etc.  One morning I opened the front door to see a male kestrel sitting in a birch tree at the edge of the lawn and looking toward the vole's hole 10m away.  Perhaps it had noticed the trail camera and was wondering what the fuss was about.

I read in Wikipedia that a kestrel eats 4-8 voles per day, so roughly 2200 per year, or 4400 per year per pair.  Nestlings each require an average of 3-4 voles per day, there are on average 5 chicks per brood, and fledging takes 32 days, so that is another 600 voles, plus extras for newly fledged birds before they learn to hunt.  In round numbers this means each kestrel pair will get through the equivalent of 5000 voles per year (they do eat other things as well).  Each female field vole produces about 30 offspring per year so you can see it takes an awful lot of voles to feed just one kestrel pair. No wonder there are about 75,000,000 field voles in Great Britain at the end of the summer.

One day the camera detected a burglar.  The first time it sat outside the hole for about half a minute, loitering with intent.  The second time it appeared from inside the hole, ran in and out a couple of times and then ran off.  This is a wood mouse (Apodemus sylvaticus).  I don't know whether it was casing the joint or was hoping to take lodgings.  If you thought a field vole was fast have look at the mouse.

These pictures were recorded with the Wingscapes BirdCam Pro, which has the advantages of adjustable preset focus and white light LEDs for colour video at night.  When I used it on the sparrowhawks last month the pictures were a bit overexposed and the output of the LEDs is not adjustable.  So I have modified it by fitting the lenses from a pair of child's sunglasses from Poundland over the two LEDs.  Whether due to that or not, the nighttime video exposure on the vole and the mouse here looks better.

I hope the vole evades the kestrel and sticks around to enjoy the meadow when it flowers in a few months time.  If it does, and I manage more photos, I'll post them here.

25 years of BTO Garden BirdWatch

The last time I saw a yellowhammer in my garden was on 31st December 1994.  It sat in the kitchen garden for an hour or so, the day before the BTO (British Trust for Ornithology) Garden BirdWatch (GBW) was due to go live.  I had high hopes of starting off with a yellowhammer - but I haven't seen one here since.  I didn't get a photo either - this is Thomas Bewick's woodcut.

GBW is a citizen science project whose participants submit weekly records of birds seen in their gardens.  It is funded by contributors' subscriptions.  The number of contributors rose from 2,000 in the first year to a peak of over 12,000 in 2003 but I was surprised to see that it has gradually tailed off to 6,000 last year.  The number of submissions peaked at almost 500,000 per year and now runs at about 250,000.  

In the early years of GBW the data were submitted on A4 cards to be read by a scanner but sometimes the cards were damaged in the post and couldn't be fed into the card reader (once that problem was realised we had to submit them folded in an A5 envelope) so three of my quarters were lost, meaning that I have only 97 of a possible 100, with 1250 weeks in total.

I am not one for lists but I can see from my own GBW data that I have recorded 61 bird species in the last 25 years,

The commonest birds I have recorded are:

It is interesting to see rook and pheasant on the list.  When I first moved here 30 years ago there was a rookery in the copse at the top of the garden.  At its peak there were 44 nests (and a lot of rooks) but it dwindled over time and one year they didn't return.  I can see from the GBW data that the last time I recorded a rook was in 2011 and the last nests were in 2010.  I doubt they will ever return but I would be pleased if they did.

It is also now exactly two years since I saw "my" pheasant here.  He was a daily visitor for five years and so was at least six when he was last here, very old for a pheasant.

The rarest bird sightings, with one each, have been woodcock, sedge warbler, grey heron and buzzard.  Of these, the only one I managed to photograph was the juvenile sedge warbler.

As well as the yellowhammer, other rare sightings in the garden before GBW began were waxwing, red-backed shrike, and cockatiel(!) so the garden list is 65.  (I don't have a life list, or a patch list, or a year list, or a garden year list, etc, etc.)

As well as birds, GBW offers to record mammals, reptiles/amphibians, butterflies, dragonflies and other insects, although from memory these weren't included at the start 25 years ago.  The only one I have completed regularly is mammals, although I have tried to do bumblebees, butterflies and dragonflies.  I am not sure how much use is made of these data.  I know the British Dragonfly Society doesn't use them because there is no way of validating the sightings. I suspect the same is true for bumblebees and butterflies but at least it gives me some sort of record.

I can see that I have had 16 species of mammals in the garden, with red fox the commonest and stoat the rarest.  I have had 15 species of butterfly, with commonest being red admiral, speckled wood and large white and the rarest holly blue, small skipper and small copper, each with one record.  Dragonflies are rare in the garden but I have seen eight species, the commonest, not surprisingly, being common darter.

Garden BirdWatch's main strength is its size.  It has now accumulated a vast amount of data which can be used to examine long term trends and show which species are thriving or in decline in the UK's gardens.  For example, this is the 25 year trend in reporting rate for wood pigeon.  (It looks as though we are approaching peak wood pigeon!)

Goldfinch is another bird doing well in gardens.

As is ring-necked parakeet.  Although some people don't approve of them, I would love to see one of these in my garden.

GBW data can also be used to identify birds doing badly.  These are data for song thrush,

starling,

and house sparrow, all three of which are on the Red List in the UK.

Bullfinch is a bird I see a lot here (in 35% of weeks according to the table above but in 46 of 52 weeks last year) and its numbers have also been increasing in GBW.

The data can also be analysed to show the annual pattern of garden use.  This is a plot of average weekly count (ie numbers seen) whereas the graphs above are of reporting rate (ie the likelihood of at least one bird being seen).

If you would like to join GBW and contribute your observations you can do so here.