We mentioned in our last blog about a nest that was unusual even by Stonechat standards… a nest on the floor in dead bracken but so well hidden it was literally in a tunnel. This Dersingham Bog territory (known as the Piezos) has always been renowned for tunnel nests. The current resident female’s first nest was also in a tunnel but a more standard one, partway up a clump of dead bracken which was at least visible when standing right over it.
The past occupant of this territory was also notorious for preferring to build nests in tunnels. She was our oldest ringed female, born in 2013 and last seen in early 2017. Over the 3 years she nested on the reserve, she had many of our volunteers scratching their heads trying to find her nests and used up many hours of volunteer time. She had a habit of choosing either vertical tunnels, ‘trap door’ tunnels, horizontal ones, ones at right angles, tunnels in bracken or in grass tussocks and even in dead vegetation out on the mire, and it wasn’t long before she became affectionately and fairly obviously christened ‘the tunneller’, (although unfortunately we don’t have a photograph of her).
And it’s no wonder that the current female Stonechat on this territory also has tunnelling tendencies as she’s the tunneller’s daughter, born in 2016 in a second brood in that season. So it’s in the genes! She nested last year on Dersingham Bog NNR in a neighbouring territory but this year moved to her natal territory and has produced 2 broods so far this season and is currently incubating a third.
Other progeny of the original female have also exhibited a preference for tunnel nests and it’s an interesting trait and something which we wouldn’t be aware of but for the CR project.
Not only was our original ‘tunneller’ our oldest ringed female but she has proved to be our most prolific. She would regularly be the first to start breeding each season and would bring off 3 successful broods in a season, each with high brood sizes and with different partners in the three seasons she bred between 2014 and 2016.
Either directly through her direct progeny or through her progeny’s progeny, she was responsible for 116 juvenile Stonechats, which is an amazing number and accounts for a third of our total number of juveniles produced on Dersingham Bog since the project began in 2012. Many of the new pairs occupying the reserve in the last few years have been her progeny, which in turn have produced juveniles of their own which have then dispersed into the Stonechat population.
And those juveniles are just the ones we know about. At least 2 of her juveniles have been reported from a range of other locations, such as Snettisham Coastal Park and Winterton, and those in turn may also have bred successfully. So the final total of chicks which carry her genes may be even higher. We also missed a couple of her broods during the time she bred on the reserve. So this one female surely must have played an important role in Dersingham Bog becoming almost like a nursery for our locally recovering Stonechat population… or at least it was until the Beasts from the East devastated our numbers.
To flesh out the figures a little, our matriarch produced 24 young while breeding on Dersingham Bog NNR in just three seasons. And of those 24 juveniles, 9 Stonechats of her direct progeny returned to breed and set up their own territories in 2015, with 2 reported breeding elsewhere in Norfolk, and those 9 now have a large number of descendants from the last two seasons.
It’s a remarkable legacy for one small passerine and one that was only breeding for 3 years but it goes to show quite effectively how much of an impact a bird like this can have. She has formed the core of our Stonechat breeding population and the breeding picture on Dersingham Bog NNR over the past few years may have been very different without her.