Holt! Who goes there?

These are not recent pictures but they have not been published before.  A couple of winters ago I had very privileged access to an artificial holt.  It was difficult to get to and I was wary of visiting too often for fear of spooking any otters that might be using it.  In the end I left the camera for a few weeks at a time but found it was mostly filled with recordings of ducks and geese.  It also recorded plenty of passing deer, foxes and badgers but fortunately there were a few otter sightings as well.  The holt wasn't used regularly by otters, but was just an occasional stop-over place.  There were very few daytime recordings but this was one.

Here is a brief montage of four night-time sightings.  In the last one an otter ran into the holt but then heard a rat running overhead and came out immediately to give chase.  I don't know if the pursuit was successful as it didn't return.

I may see if I can put a camera there again one day.  My greater ambition would be to find a natural natal holt with mother and cubs.

My new bee house

I have just finished making the new, improved, deluxe, mark IV bee house (2023 model).  The central section is fairly conventional but also contains a solid piece of rotten wood, in the hope of attracting fork-tailed flower bees.  The side doors are recycled from my old kitchen units.  They extend in front of the rest of the house so I can put on a wire mesh to protect against woodpeckers and blue tits.

The side panels are covered by perspex so I shall be able to see the occupants.  Three are made out of dead sycamore and the fourth out of rotten dead sycamore.  It was interesting machining the wood but I hope it will have been worth it.  I have put in a mixture of 3, 4, 6 and 8mm holes to attract a variety of species.

The panel with rotten dead wood has just three short starter holes because fork-tailed flower bees apparently like to excavate their own holes.  If one does come in I hope it will stay next to the perspex so I can see what it is up to.

I have transferred canes and tubes etc, some of which contain bees, from the mark I bee house which is now retired.  (The mark II and the mark III are still in use.)

Since taking the above photos I have modified the top section with another log to make it easier for bees using that to get their bearings and I have fitted a clip-on wire cover to protect against blue tits and woodpeckers.  The bees can easily fly through the mesh and I can remove it for photos.

So it's all set to go.  I'll report back later in the spring or summer on which bees have moved into this luxury accommodation.

Otters in early morning

The cubs are now nearly as big as their mother.  These pictures are from last weekend when there was a short freeze and a thin layer of ice.  Mother otter and her two cubs appeared in the early morning and played at the water's edge for a couple of minutes.  As luck would have it I had moved two cameras to another nearby site (more news soon) and the light was difficult for this camera, looking straight into the reflection off the ice.

The second camera was looking the other way and because it had less light it was still in night mode (infrared and therefore black & white) so I can't edit the two videos together.  Also, as you'll see, the otters were a bit too close and too low.  Still, it's worth a look.

A couple of hours earlier they had visited the same spot.  As ever, one cub was lagging behind and the other two had to wait for it.  There is a good view of the smaller cub swimming under the ice.

I have my fingers crossed that the other cameras will turn up trumps.  I hope to have more news soon.

My latest wildlife yearbook

My 2022 photobook has just been published.  As usual, there was a print run of only two but it is available to view online for free here.

A cob brick bee house

March is the time to look out for hairy-footed flower bees (Anthophora plumipes), one of my favourites.  They fly in spring, being among the first solitary bees to emerge from hibernation. They nest in cob walls and old mortar, often in large aggregations.  Their whole season is over by early summer and the next generation of bees waits in the safety of the wall before emerging the following spring to start the cycle over again.

I read an article in the BWARS magazine by John Walters, an entomologist from Buckfastleigh in Devon, on making a cob brick bee house for hairy-footed flower bees and was inspired to have a go.  A year ago I followed his recipe using cricket pitch loam mixed with a little sharp sand, some chopped straw and enough water to make it all stick together.  You can see John Walters' videos on how to make cob bricks for hairy-footed flower bees, part 1, part 2 and part 3.  I also took advice from my friend Chris Henderson, a retired doctor and renowned mud-brick house builder in Tasmania. Chris said the secret is to let the cob dry slowly, out of the sun, so it doesn't crack and fall apart. The bricks then have to be kept dry and put where the bees can find them.  I built a shelter from a few old planks and put it close to some pulmonaria plants, the bees' favourite flower.

I didn't see bees flying into the bricks while I was watching but within a few weeks there were signs of activity with what looked like spoil from excavation below a couple of the holes and at their entrances.

When I peered in at the end of the season with a macro lens and ring flash I could see something at the end of four of the holes.

My hope is that these are sealed bee nests.  I found a PhD thesis written by Radha Devkota Adhikari on the use of the hairy-footed flower bee for strawberry pollination in greenhouses in Japan.  It includes this photo of the inner structure of a nest and says "the inner walls of both provisioned cell and pre-chamber were coated white" so this could be what I am seeing in mine.

I have set up the bee house again, ready for the bees to emerge (I hope) later this month.  Ever the optimist I have also built a small cob-filled observation panel with a perspex window in the hope that I may be able to see what happens inside.  There are four small starter holes and if a bee does move in I'll keep my fingers crossed that it excavates next to the window so I can see what is going on.

I have also built a much more stylish Mark II version for the new season.  It contains Victorian land drain pipes filled with the same cob.  It is now in position in the hope that the bees will take to it.  If they do I'll post an update here.

Otters on the ramp

This was the first time the cubs have been up the ramp.  I put it in three years ago after seeing one cub dragged by its whiskers as its mother tried to lift it up the sluice gate.  This mother is used to it and bounded up but you'll see here that the cubs were a bit confused in the dark and took a while to sort it out.  The recording stopped after 20s and they were too far away to re-trigger the camera.

Both cubs are tending to lag behind their mother now as they get bigger and move towards independence.

On another occasion the mother was carrying prey but I can't make out what it is - possibly a duck or a rabbit.  Whatever, it would make a good dinner and one cub was very keen to share and keeping very close behind.  The other was over a minute behind but they did wait for it at the top of the ramp.

The next time they were coming down.  Only two otters which look the same size, so these may be the two cubs.  They are now confident with the ramp and the second one, literally, takes a leap in the dark, landing with a splash.

There has been a lot of coming and going in the culvert this past week.  Here they are both dawdling again and mother has to wait for them to catch up.  There is a rather unsatisfactory blend from the first cub into the second as the camera stops recording after 20s and then restarts.  This is an intrinsic limitation of Browning cameras which are otherwise pretty good.

There was also a brief sighting of a dog otter with prey.  It isn't easy to see but it was carrying a long-legged, dark-feathered bird, so very probably a moorhen.  It went past four cameras but unfortunately it was travelling fast and going away so we only get a view on the first.