Aftermath

It’s a week on from the destruction of the kingfisher and sand martin nests by the mink. During this time I’ve had several discussions with the landowner and the local Wildlife Trust which has resulted in permission being granted to trap the mink. On Friday evening I placed a trap in an area I’d seen the female mink moving through regularly, and on Saturday morning I returned to be met with shrill distress calls emanating from the area around the trap, as I approached the trap there was frantic calling from the undergrowth and I saw three juvenile mink kits being led away from the vicinity of the trap by the adult. Part of the cloth cover I’d put over the trap to create the impression of a cave was chewed and through the hole I could see a juvenile mink inside the trap.

Inline with GWCT guidelines on mink trapping, the juvenile was quickly dispatched using an air pistol and I’m now left with the knowledge that the female has at least 3 healthy & mobile juveniles in tow that she will be foraging for. Intervening in an ecosystem is seldom straightforward, and unfortunately there are no easy solutions to problems like the mink.

As for the kingfishers, on my last two visits to the site I’ve only seen the adult male on the branch opposite the nest site, where he has perched for a few seconds before resuming his flight upstream. At this point it looks like the kingfishers have abandoned the nest bank, presumably to try and find a safer site elsewhere, there is also no sign of the Sand Martins.

Kingfisher nest predation by Mink

For the second year in succession, the kingfishers have lost a nest to predation by mink. The kingfishers had been incubating for about 2 weeks when the mink struck, predating the Sand Martin nest and the Kingfisher nest within a matter of minutes.

The only piece of positive news in this is that the adult female, who was incubating at the time managed to exit the nest before the mink entered, so both of the adults have survived the attack and still have time for another brood.

What this incident has highlighted though is how vulnerable these nest banks are to Mink. During the time I’ve been observing this nest site, I had assumed that the entrance was safe from the Mink, being over 4ft above the base of the bank and dug into a loose sandy clay bank. Although the Mink struggled to enter the Kingfisher nest, it managed to get in after only a few failed attempts, and entered the Sand Martin burrow on its first attempt. Coming a week after many of us watched a Mink predating a Kingfisher nest on the BBC during Springwatch, I think this goes to show how much of a threat these introduced predators are to bank nesting birds like kingfishers and martins.

Half an hour after this event, the male was removing egg shells from the nest burrow.

I very nearly left my hide to try and scare the mink off while this was unfolding, however, I’m certain the Mink would have returned after I left and so I decided to document what happened without interfering, however I will now be discussing mink trapping with the land owner

 

Another flood & a collapsing bank

On the day that the kingfishers began incubating their second brood the rain started again. A week later and the water levels are pretty much where they were during the floods in April. During my visit to the nest site on Saturday 9th June, I’m horrified to see a substantial section of the bank directly beneath the kingfisher burrow collapse into the river. The kingfisher burrow entrance, that had been in the middle of a smooth bank face, was now overhanging a gaping hole where the bank had collapsed away.

When the collapse happened, the female, who was incubating at the time, immediately exited the burrow and seemed very reluctant to return to the nest. She repeatedly flew across the river and hovered near the burrow entrance, but just didn’t seem to have the confidence to enter. A few minutes later she flew off downstream. Fortunately, the male returned to the nest shortly afterwards and flew straight into the burrow as if nothing had happened.

I stayed on site to wait for the female to return and I’m pleased to say that an hour later she returned. She perched opposite the nest and called to the male, who immediately flew across to perch next to her. A few seconds later the male headed off downstream and the female flew across to the burrow and entered. The following morning both birds were continuing to take shifts brooding and the water level had receded a couple of feet, exposing more of the chasm below the nest burrow. The nest chamber itself is about 2-3 feet into the bank, but if the top section of the bank collapses, it’s anyone’s guess as to whether the nest will remain viable.

In a final turn of events, the disused burrow to the right of the kingfisher nest was once again being visited by Sand Martins on Sunday morning. The martin’s were present most of the time I was there (about 3 hours), perching at the burrow entrance and entering, sometimes two at a time. Whether they’ll move in this time remains to be seen.

Digging, feeding, breeding & brooding


In the last week a lot has happened at the kingfisher nest. By the 29th May work on the burrow had been completed, the resumption of mating being a sure sign that the burrow was now ready for a second batch of eggs. During the following week the kingfishers continued mating, the ongoing courtship display of calling, fish passing and mating all happening around the nest site. The female intermittently visited the nest burrow throughout this period, probably laying an egg each day.

Once the female has completed egg laying, the kingfishers behaviour changes markedly as they begin incubating the clutch, and when I arrive on Monday 4th June I sense straight away that things have changed. After seeing and hearing nothing for 45 minutes, the male bird arrives opposite the nest, calling loudly as he arrives. The female hears the male and exits the nest burrow almost instantly, she flies across the river and they perch a couple of feet apart on a branch calling to each other, the female affecting an extravagant upright posture. A few seconds later, she takes off and heads upriver, the male sits on the branch for a few seconds more and then flies across the river straight into the nest burrow, incubation is now underway.

All being well, the adults will now settle into a routine for the next 3 weeks, changing over at the nest about once every one and a half to two hours. When the adults are not brooding they leave the nest site after a brief hand over, and don’t usually re-appear until they’re ready for their next shift. I’m not sure how far they go, but I’ve seen them over a quarter of a mile down stream still flying away from the nest during this phase. I wonder whether they are taking the opportunity afforded by these extended breaks to re-acquaint themselves with their territory, perhaps ensuring that no other kingfishers have encroached while they’ve been busy around the nest site.

I’ve seen no further sign of the first brood fledglings since a fly past the nest site on the 25th May. The mortality rate in young kingfishers can be very high during their first few weeks of life, but hopefully the brief heatwave during the latter part of May will have given them ideal conditions for starting out, and judging by the amount of small fish in the river, they shouldn’t have had too much trouble finding something to eat.