Nest predation

nest-predation2

While everything has been going well with the Dutch kingfishers, on the Trent things have taken a disastrous turn. My local birds appeared to have been running about 2 weeks behind the dutch birds and I was expecting to see fish being taken into the nest this weekend. On arrival this morning at the nest site I sensed something was wrong, both birds were outside the nest flying upstream and downstream and perching below the nest borrow entrance. The female wouldn’t enter the burrow, and while the male entered, he came out immediately.

My usual viewpoint is on the opposite bank from the nest, so I had to drive and walk across a field to access the nest bank. As soon as I arrived I could see that the nest had been dug out from above, there were egg fragments on the ground, and a hole going straight down to the nest chamber, which was about 10 inches below the surface.

nest-predation1This has happened before at this site, in 2011 the same thing happened, so I had placed a metal grid above the nest chamber for each of the last two years. The metal grid I’d placed above the nest this year looks like it was just a bit too far back, and the unknown predator had dug down at the side of it. I’d assumed the nest would be about 3ft from the bank face, but unfortunately it was only about 18 inches deep, so it remained exposed, despite my efforts to protect it.

I had thought that it was the noise of chicks in the nest that might bring about this type of raid, however, this nest obviously still contained eggs, so I’m assuming that the predator was using scent. It’s probably fair to assume that the regurgitated pellets that the kingfishers use to line the floor of the nest chamber must have a fairly pungent scent.

The only positive I can take from this is that both adult birds appeared to be fine. If they dig a new burrow I will use a larger grid to try and ensure that the burrow is protected. It does concern me though, that if this has happened twice in three years at this location, how often is this happening at un-monitored kingfisher nests along the river.

Double jeopardy

The Kingfisher nest site has been the centre of a lot of drama in the last couple of days. Two serious threats to the Kingfishers have cropped up and although one has now been dealt with, the second is still present and I’m considering what can be done about it.

The first problem became obvious when I visited the site to observe the brooding behaviour on Thursday morning. From the opposite bank, I watched in horror as a herd of bullocks shoved there way past and even jumped over the fence protecting the area of the bank with the Kingfisher nest. The fence was put up a few years ago after cattle had stoved in the bank and destroyed a nest in 2004, so to be fair it wasn’t in great repair, however until today I thought it was still servicable. After driving round to the location where I access the bank on the Kingfisher side of the river I managed to lure the cattle away from the bank and then surveyed the damage.

I’d seen the cattle jostling and bucking directly above the nest hole, so I was fairly concerned and on examination a clod of earth was missing directly above the hole. On the plus side, the Kingfishers were still in attendance and I watched in some relief as the male entered the burrow and stayed in for a brooding session.

Once I’d established that the nest seemed to be intact I contacted the estate office and despite them being shorthanded over the easter weekend they were great and we managed to organise a fencing repair the same day. If we hadn’t repaired the fence, I feel certain that the bank with the nest in it would have been lost within days.

So on Thursday lunchtime we had the tractor down at the site and a new fence was erected. We kept the new fence posts as far from the burrow as we could, but I was very aware every time the posts were bashed in of the potential disturbance to the burrow.

So it was with some trepidation that I went down on Friday 6th to monitor the site from a distance using my bag hide. After half an hour I was really pleased to see the male emerge from the burrow and after a brief fishing session opposite the nest return to brooding duty. The male emerged from the nest 3 more times until finally, the female returned and entered the burrow. So, I still have both parents apparently brooding normally despite the disturbance.

However, the Kingfishers were not all that I saw on Friday.

I had been sitting in cover with my bag hide completely covering me for about 2 hours when I heard a noise directly behind me. I slowly turned round and through the small hole in my hide I stared straight into the face of an adult Mink sitting upright sniffing the air and trying to work out what I was.

After a few seconds it disapeared for a minute or two and then re-appeared and ran straight in front of me no more than 5 feet from my feet. It hopped over a tree trunk and then to my horror dropped down into the river and swam straight to the undergrowth right next to where the male Kingfisher has been fishing from a low perch in between brooding sessions.

I watched as the Kingfisher emerged from the burrow and perched no more than 6 feet from where I had last seen the Mink. After a few seconds the Kingfisher dove into the water, caught a fish and moved to a safer perch. After the Kingfisher had returned to the burrow I watched the Mink emerge from close to where the Kingfisher had been fishing and trot along a fallen tree branch overhanging the river.

Well, that was as much as I saw today. How much time that Mink is spending in the vicinity and whether it could create an opportunity to ambush the Kingfishers I simply don’t know. Either way it re-enforces my intention to protect the burrow from being dug out from above as it was last year, I just hope the adults are going to be OK. As I watched it bought to mind Charlie Hamilton Jones’s film Halcyon River Diary, where a mink ambushed a pair of fighting Kingfishers, so mink are certainly capable of predating adult birds.

On the plus side, when I left both adult birds are still present and behaving normally, the bank is now protected from the cattle and so far the Mink obviously hasn’t figured out a way to ambush them.