Stonechat season – round one

Following our thankfully milder winter and with Stonechat occupation of Dersingham Bog NNR at a good level, hopes were that our 2019 breeding season would get off to a good start and so it proved.

SC female Boardwalk 2019

Photo Les Bunyan

As mentioned in a previous blog, with 8 territories occupied at the end of the winter, some of those pairs remained on site for the spring, while new pairs arrived and some Stonechats from last year’s season returned to their 2018 territories, ousting the winter incumbents and some took up new territories entirely. So we started our first round of breeding attempts with 10 pairs, and with 3 new survey volunteers to add to our survey team, spirits were high.

With little poor weather through April, our Stonechat pairs breeding attempts progressed well and as we now come to the end of that first round of nesting attempts, we’re delighted to report that we’ve ringed 25 chicks, with a further 4 chicks to add to the total from a pair that snuck off a brood right under our collective noses!

SC Phils 1st brood 2019The clutches have been fairly small, with more than usual having just 4 eggs as opposed to the usual 5 and we’ve also had the usual spread of some unhatched eggs within those clutches. We’ve had 5 broods of 4 chicks, with 1 brood of 3 and 1 brood of 2 chicks. So we might have expected more chicks from a first round attempt with such a good number as 10 pairs but at least it’s a good start.

All our pairs nested early for their first broods, which bodes well for them attempting a second brood, and possibly even a third if the weather cooperates. Unusually, and unlike previous years, our first brood pairs have not been synched with their timings, which at least has helped spread the volunteer workload more evenly. We’ve had some pairs on eggs while other clutches were already hatched or with chicks nearly ready to fledge. The pair that managed to sneak a first brood off unseen must have started incubating in mid-March which is incredibly early.

SC Predated Tranquil nest 2019We’ve had two failures, one predated on young chicks and one clutch of five eggs which didn’t hatch. That female sat it out to the bitter end, incubating for well over the usual two week period before abandoning the clutch.  The failure on chicks also seems to have triggered a change in female. Whether she was predated as well or she just abandoned her partner and the territory after she lost the chicks is unclear, but either way, the male seems to have attracted another female relatively quickly. He’s busy displaying and establishing the pair bond, so hopefully his new female will begin a nesting attempt soon. As far as we can tell, there have been no other partner changes, although our volunteer survey team is in the process of confirming that – back to their regular pastime of peering at Stonechat legs!

SC chicks 9 days old Pylon 2019(1)At the moment, we have a range of fledged juveniles of varying ages scattered across the site – some just fledged and hiding in the undergrowth as they complete their plumage, and still being actively fed by the parents. Others are well-developed and flying well, with only the occasional bout of feeding by the parents. Sometimes it’s more a case of the juveniles chasing after the parents for food rather than the adults actively seeking the youngsters out. So it won’t be long before these youngsters disperse from their natal territories but many are likely to remain on the reserve for a while yet.

Landfill West SC 1st brood 2019The nests were in a range of habitats and situations, as we’ve come to expect from our Stonechats. What is typical, as we’re learning, is the habit of choosing nest sites close to paths or tracks. Of our 9 found nests for this first round, 7 were close to the main track and, in some instances, literally within a couple of feet of it and, therefore, very vulnerable to disturbance and predation. Yet these are large territories so the females could easily choose a more secluded and undisturbed site.

 

SC-Happy Valley 1st nest 2019The nests close to the path had no common theme in the type of nests or vegetation chosen. 5 were in heather, with 2 nests at ground level and 3 a foot or so off the ground in the middle of sparse heather bushes. The other 2 were in dead bracken, one tucked under a ‘shelf’ on the lip of the main path and very vulnerable, and the other was in dead bracken right on the ground by the path. This was the nest predated on chicks, so its exposed position might also have contributed to its vulnerability to ground predation.

We’ve already seen nest-building from some of our second brood pairs, while at least 2 pairs have only just fledged their first brood young. So we can expect the second broods to be equally spread out in terms of timing. Several of our core territories remain empty so there is still room for more occupation if extra birds arrive and at the time of writing, 2 pairs seem to have moved to their neighbouring territories. It’s unclear why as both pairs were successful on their initial sites and each territory is considered prime Stonechat ‘real estate’ so we’ll have to see how they progress next time round.

WL nest 2nd brood 2019 Sheperds - predated (1)Our Woodlarks have not done so well so far this season. We’ve only one active pair, as far as we can judge, and while these were successful with their first brood, bringing off 2 youngsters with 2 unhatched eggs left in the nest, their second brood has just failed, with the eggs being predated. Other than lone singing males on two other territories, there don’t seem to be any more active pairs and some of our previously occupied territories now appear empty.

So far we have 8 singing male Tree Pipits establishing territories on the reserve and we’re now starting to get to grips with how many are paired and work will soon start to find those which may already be on eggs. As we begin the preparations for the first of our reserve-wide Nightjar surveys this week, with Tree Pipits now on site, efforts being made to find any Woodlark we might have missed, and our second brood Stonechats about to get underway, one thing Dersingham Bog NNR doesn’t lack is variety!

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Stonechats – it’s all in the voice…

This is a good time of year for experiencing the considerable variety of Stonechat vocalisations. Both males and females utter a range of alarm and contact calls and song during the breeding season which mean specific things at different times of the cycle. Combined with visual clues gleaned from their behaviour, these vocalisations can help work out what stage of the breeding cycle each pair are at.

At the moment on Dersingham Bog NNR, we’re hearing just about every possible variation as our Stonechat pairs are at different stages of their nesting attempts, with some still on eggs, some with hatched young and some already with fledged juveniles.

Stonechat Roydon Les Bunyan

Photo courtesy of Les Bunyan

SONG
Only the male Stonechat sings and the peak song period is March and April. It can then cease, apart from brief peaks just prior to the start of each new nesting attempt but declines when the young hatch. Males can sing in good weather throughout the day and not necessarily at dawn. The frequency of song also depends on the nearness of neighbouring territories, with boundary disputes often triggering a burst of song from either male.

Song is also given by the male Stonechat as a distraction technique when observers are approaching a nest area, or are inadvertently sitting or standing too close, as a kind of ‘look at me’ technique by the male, or a distraction to allow the female to leave the nest unobserved. There is also a subdued version of the main song used in a similar fashion as a distraction.

CALLS
Both males and females utter a variety of calls, chiefly used as a warning or distraction. The warning call is usually a short, clear single note whit – often uttered by the male when observers are approaching the nest area and may be used to warn the female not to leave the nest. This is often followed by the male flying away from the nest area, leaving the female still sitting. It can also be used to warn young in the nest and recently fledged young to remain silent.

The distraction call is a harsh chack. Uttered by both sexes but more often by the male, it’s frequently heard when the incubating female is on a feeding circuit if observers are too close to the nest and may be preventing her from returning to it. This call is often accompanied by short flights and wing and tail flicking to try and distract observers away from the nest and towards the calling adult.

SC female unringed Stefan Oscarsson Thornham Feb 2019AThe whit call is most often used during incubation and the chacking call comes more into play when the young are hatched and being fed in the nest. All the calls increase in volume and frequency the closer an observer is to the nest and decline as the person moves away.

The whit call can also used by the male to call the incubating or brooding female from the nest for a feeding circuit if he perceives no threat – i.e. an observer is far enough from the nest area; although she may also be reluctant to leave the nest if the young are close to hatching. However, when the young have hatched, she can also leave the nest immediately upon hearing the call, so observing behaviour as well as listening to the calls becomes crucial at this stage in order to work out what’s going on.

There is also a much harsher double chack with a click-click note at the end which is given loudly and constantly by both sexes if observers are near a nest with well-grown young or recently fledged young. This is also accompanied by both parents trying to distract with wing and tail flicking and flying towards the observer and then away again, to try and ‘tempt’ the intruder away.

SC-Flat Nose Nth Male + 1st brood juv 2017 Benno Zeelte

Adult male with recently fledged juvenile. Photo courtesy of Benno Zeelte

Calls increase in volume and frequency as the young grow, reaching a peak when the young are near to fledging and continue after they fledge, particularly in their first week out of the nest. While the male continues to feed the young after fledging and will alarm if a person is near, the calls will gradually decrease as another nesting attempt begins when the female begins building another nest and the young from the previous brood leave their natal area or are chased off by the male. Fledged young also have a hoarser chack call which they give as begging calls for food or in response to an intruder; it’s a subtly different note from the adult’s chack call.

Each pair is different though and some we’ve found are very tolerant of a fairly close approach to the nest before they will alarm, regardless of what stage they’re at in the breeding cycle, while others will alarm when observers are some distance from the nest area. Pairs can also alarm when a ground predator is present or corvids but they rarely seem to alarm in response to the presence of birds of prey.

Both sexes can utter a variety of other interesting calls at different times, including a brief hoarse rattling krrrrr which is used in song flights or territorial defence and the thin seeseeseeseesee call is usually given by the female. Nestlings can sometimes be heard calling shree shree shree shree, although in practice it can be difficult to hear until a person is standing right over the nest or it’s a call they can give sometimes when they’re handled.

SC male Tranquil valley unringed2This only covers a fraction of the vocalisations Stonechats can produce. The song is especially varied and given in a variety of circumstances. We’ve just covered the ones which are helpful to our volunteers in their survey work, particularly in the nest-finding process, and helping to judge the relevant stage of the breeding cycle so volunteer time and effort can be planned more effectively. There’s a whole other article in trying to cover the display and song patterns and behaviour of this charismatic chat.

If you’re curious to listen to some of the vocalisations, Xeno Canto is quite a good resource for examples of the different calls and songs – https://www.xeno-canto.org/species/Saxicola-rubicola

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Stonechats elsewhere

As well our ringed Stonechats wintering on the reserve, we’ve also received some interesting sightings this winter of our ringed birds from elsewhere in Norfolk, with both birds born last season on Dersingham Bog NNR being reported and the first sighting of a bird born several years ago but not reported since. Birds have been seen at Heacham, Deepdale Marsh, Roydon Common and Holme Bird Observatory.

Of our crop of 48 ringed juveniles last season, so far 18 ringed birds have been reported to us, which is a good reporting ratio as well as a survival rate for the juveniles; no doubt helped by the milder winter this year. It’s interesting to speculate how many other Stonechats from last year’s ringed crop have survived and just not yet been seen or reported to us.

Of those 17 reported Stonechats, 9 are now on territory on Dersingham Bog NNR, with 1 more ringed male seen in mid-winter but who no longer seems to be around. Of those reported ringed birds, 10 were male and 6 were female.

SC juv Happy Valley -2nd brood Deepdale Marsh Mark AndrewsOne male was been tracked this winter from Deepdale Marsh along the Norfolk coast and is now on territory at Thornham, where he is paired with a female and appears to be breeding. That male was first seen at Deepdale last September just a couple of months after he fledged from a second brood of one of our core territories, so a decent distance for a juvenile who’s not long left the natal site.

SC juv Bryants 2nd brood Deepdale Marsh Mark AndrewsInterestingly, at the same time he was seen at Deepdale, there was another of our ringed males at the same site. While the second male was also born last season, it was from a different territory on Dersingham Bog and these males fledged a month apart. Amazing then how they ended up at the same spot at the same time.

Another of our ringed males has since appeared at Holme where he is similarly paired with an unringed female and currently feeding first brood young (thanks to Pete Bangs for this most recent photo).

One ringed male was seen by one of our survey volunteers, Les Bunyan, on Roydon Common and it’s the first report of this bird since he fledged from Dersingham Bog in 2015. It’s entirely possible he’s been at Roydon for a while but perhaps just not reported?

Male SC Winterton March 2019 Ringed - photo by Dave RobertsA tantalising glimpse of a ringed male at Winterton by Dave Roberts was probably one of our birds too, although the ring combination couldn’t quite be nailed down but hopefully if the bird remains at that site and breeds, someone may yet get a better view of its ring combination.

Snettisham Coastal Park seems to be a good ‘gathering ground’ for Stonechats in general, both in the winter and in the breeding season, and Ray Roche reported a ringed female seen there in April this year, so it’ll be interesting to see if she pairs up and breeds.

We’re very grateful to everyone for reporting their sightings and for the cracking photos submitted and for allowing us to use them on the website and our Twitter feed. We can only plead for more sightings really – we’d love to hear from anyone who sees a ringed Stonechat, even if it’s not one of ours! We’d especially like to hear of any which are successfully breeding, both in Norfolk and elsewhere.

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Winter Survival

After a milder winter than last year, we head into the start of the 2019 breeding season at Dersingham Bog in a much better position than we were last year where we were just thankful some of our Stonechats had even managed to survive the double Beasts from the East.

We’ve had 7 territories almost consistently occupied throughout the winter on the NNR and those same territories are now getting a head start in the breeding season.

Bog sunrise0_001As we started to see in previous years, the same pattern repeated itself this winter with some of the territories occupied by the same pair that bred last season and who are now well on with their first brood for this year. Other territories have seen completely new pairs wintering and those too are now also well established as a pair, with some of the females now incubating.

Other territories which were occupied by a new wintering pair have now been ousted by the returning Stonechat pair or single birds from last season. Those are slightly slower to start off this breeding season as they are still establishing or re-establishing their pair bond and the female is busily feeding up to get into breeding condition. And we also have completely new pairs still appearing on site.

Female Piezos Feb 2019

Photo courtesy of Les Bunyan 

We’ve also had a few Stonechats appearing on the reserve through the winter, holding territory for a short period before disappearing again, or being replaced by another new ringed bird. Again, without the colour ringing project, we would not have been aware of these changeovers.

 

Currently we have 8 occupied territories and there’s plenty of time during April for more to arrive, as has happened in previous seasons. In contrast to last season, we have 8 ringed birds on site, including 1 ringed bird with just a metal ring and no colour rings, so not one of ours…

SC female Boardwalk 2019

Photo courtesy of Les Bunyan

One of the pairs in a core territory at the western end of the reserve is a bizarre mirror image of colour rings – the male being green/metal and green/grey and the female sporting metal/green and grey/green. What are the odds of that combination pairing up?! The male was born in 2017 but has not been reported since fledging, so it’s intriguing to wonder where he’s been in the intervening period.

5 of our ringed birds currently on site were born last season and we’ve had reports of 13 of our 2018 juveniles in total, including reports from other areas, which is a good ratio for a season with just over 50 fledged juveniles in total. 2 of our current males are the 2018 breeding season males back on territory but so far none of our 2018 territory females have returned, but we did have a very low ratio of ringed Stonechats on site last season.

One of our ringed females born last year has returned to her natal territory but overall that tends to be unusual – all our other ringed Stonechats have occupied different territories to where they were born, lessening the odds of them pairing with their own parent if they in turn were still on territory.

SC Phils 1st brood 2019

The milder weather over the winter and, in particular, the unseasonably warm spells in February and March have led to our pairs not only surviving the winter, unlike last year, but starting their breeding cycle early. We already have 4 females incubating, 1 nest building and 3 more pairs established and hopefully also about to start. If this trend continues and the weather is good, we could well have 1st broods fledging by the end of April, so fingers crossed.

Unlike last year, it actually ‘feels’ like spring on the reserve compared to last year, with lots of birdsong and good numbers of Crossbills, Siskin, Redpoll and Brambling around, and increasing numbers of Linnets already in residence and nest-building.

SC Triangle - 1st brood nest 2019None of our work would be possible without the hard-working volunteers on Dersingham Bog who spend each winter clearing scrub to maintain a habitat suitable for ground-nesting birds, and we thank them for their sterling efforts.

We’d also like to welcome 3 new volunteers to our survey team, Alastair, Keith and Les, and we look forward to working as a team throughout the summer on our target species of Stonechat, Woodlark, Nightjar and Tree Pipit. Plenty to keep us all very busy indeed!

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Life as a survey volunteer on Dersingham Bog…

As the survey work on Dersingham Bog National Nature Reserve goes from strength to strength and the Stonechat project continues to be such a success, it’s an appropriate time to pay tribute to our hard working volunteers and say thanks to Roger, Irene, Tony, Molly, Jason and Allan for all their efforts this year.

SAM_3753We are still very actively recruiting volunteers for our survey work on the reserve and would very much like to hear from anyone interested in joining us as we plan next year’s survey work. The main focus of our survey work is to survey, monitor, nest-find, and ring where appropriate, our iconic Dersingham Bog species of Stonechat, Nightjar, Woodlark and Tree Pipit.

But rather than us extolling the virtues of volunteering on the Bog and how rewarding it can be, it’s easier to let one of our volunteers, Tony, sell it for us…NJ 2 chicks-Kestrel box site 183

Having recently retired into the area, and being an enthusiastic birder, I was keen to explore local opportunities to volunteer.

One interesting piece of work that caught my eye as I searched the internet was that of the NW Norfolk Stonechats group on the Natural England Reserve National Nature Reserve of Dersingham Bog. Their website provided fascinating information about Stonechat activity on the Reserve, together with an invitation to get involved if you could spare some time.

I made contact with the group and with impressive speed, I was receiving a comprehensive briefing from Natural England in their office in Wolferton on their work on the Reserve, together with the necessary Health and Safety stuff.  No mention at all of midges, I recall!

Juv Stonechat1A week later I was on the Reserve to meet Roger and Irene, two current and experienced volunteers, and begin my initiation into the fascinating world of Stonechats. The project aims to survey, nest find and colour-ring breeding Stonechats on the NNR and record adults and juveniles outside the breeding season. The project also gives insights on whether individual birds are site faithful, as well as generating data on productivity and fledgling survival.

Over the next few weeks, my initial concern about knowing very little about the target species, and being worried about doing the wrong thing at the wrong time, was replaced by growing confidence and a genuine interest in these characterful birds. This personal development of mine was solely down to my two ‘mentors’ who between them had many years of knowledge and experience to share. And share they did! In such a positive way that I was soon hooked and really enjoying the hours spent observing Stonechat.

Triangle - SC 2nd nest 20181I was taught the art of observing and interpreting Stonechat behaviour, and encouraged to offer opinions and have a go at finding a nest or two. It’s a great feeling when it all comes together and a nest is located, young observed in the nest, the young are ringed and then successfully fledge!

And then things got even better when I was invited to take part in a Nightjar Survey on the Reserve. What an enthralling experience that was!

NJ + 2 chicks 15 days-RLine 201813Again, I was fortunate enough to team up with Irene, who is both passionate about Nightjars and very happy to share her comprehensive knowledge on the subject with a complete beginner (who would have thought Nightjar equalled churring?!). What an amazing bird!

Species nest finding and monitoring sessions on the Bog have continued and every visit brings something new – with learning different or unusual behaviours for both Stonechat and Nightjar. With plenty of encouragement and guidance, I have been fortunate enough to have helped find both Stonechat and Nightjar nests. What a thrill!

Although the season is coming to an end, I look forward to helping out with the monitoring of existing and prospective Stonechat territories over the winter on Dersingham Bog NNR, and hope that this year our winter is kinder to the birds than it was last year.

TP 1st brood Phils Heath 2018_001And I haven’t even mentioned how delightful it was to wander around the Reserve accompanied by the song of both Woodlark and Tree Pipit. Nests for both species were found this season, and survey work on the reserve next year will include both these species and I look forward to learning more about these two fascinating birds. All the nest monitoring and colour-ringing on Dersingham Bog aims to inform the management work on the reserve and enable reserve staff to plan future work for the benefit of all these iconic heathland species.

If you have even a small interest in nature, with a bias towards birds, I recommend without hesitation getting involved with a group like NW Norfolk Stonechats. They are a very welcoming and knowledgeable bunch, and the work is fascinating too. And it’s good for you and the birds!

RS + IB Triangle May 20183_001If anyone would be interested in finding out more about the volunteering opportunities for survey work on Dersingham Bog, please get in touch. northwestnorfolkstonechats@gmail.com We’d love to hear from you.

Survey experience is not essential as training can be given. Although if, like Tony, you have already participated in survey work in the past, that would be welcome. Experience with the 4 species involved is also not essential as training on Stonechat, Nightjar, Woodlark and Tree Pipits is all part of the support given to our volunteers. Contributions from ringers would also be welcome, to back up and assist Roger.

So please contact us for more details or help spread the word that we’re recruiting!

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Round three… fizzling out.

With the number of Stonechat pairs on Dersingham Bog NNR down to 5 from our original 6, we had hoped that a few of them might attempt a third brood but the season ended not with a bang but with a whimper.

Only 2 of our remaining pairs attempted a third brood, and only one of those was a ‘genuine’ third brood, at our Piezos territory. That female proved to be as prolific a breeder as her mother and produced a brood of 5 chicks for her first brood, then 6 for her second and finally 4 from her third nest.

Happy Valley SC 3rd brood 20181_001She was also the female who proved to have a preference for tunnel nests in bracken for her first two nests, again following in the footsteps of her mother and we had no reason to suspect she’d do anything different this time round. But as we were just about to have a whip round for a miner’s helmet for Roger to help him find the nest this time, she surprised us all by choosing a nest in low heather which was almost out in the open, and luckily it proved to be one of the easiest nests to find this season.

Molly - Happy Valley July 20181_001The only other third brood pair at our Happy Valley territory had a first brood failure, with the chicks predated at a week old. But that female built a second nest very quickly and brought off 6 chicks in her second brood. It was followed by another quick build of a third nest where she produced 5 young. So technically it was her third attempt but really only 2 broods were successful.

SC male Tranquil valley unringed1There was also quite a large gap of a month between the ringing of the first of our third broods and the last brood of the season which is unusual. In between, our volunteers spent considerable time trying to work out if the other pairs were going to try for a third brood or not. With one pair, the female vanished and the male went into moult quite quickly. With another pair at a different territory known, the male vanished soon after the second brood fledged and the female was left to feed the fledged youngsters from that brood herself.

The other 2 pairs were a mystery for quite some time and after much volunteer head scratching, it eventually became clear that both pairs had finished for their season. With one pair, the second brood fledged young stayed on their territory and associated with their parents for much longer than usual, even though they were well able to feed themselves by this stage, nearly two months after fledging.

The other pair had an original territory on Phil’s Heath but had fooled us all by bringing off a second brood from a nest we missed entirely in another part of their territory. As it was unclear whether there had been a failure before this latest brood appeared, we could have been looking at technically their third brood. Either way, they didn’t make another attempt.

BogThe weather remained warm and settled throughout with only intermittent rain, so the food supply should have remained good for our birds. So it’s been puzzling why more Stonechat pairs didn’t attempt third broods.

With reduced numbers of Stonechats breeding overall this year, we also didn’t get the usual gathering of fledged juveniles in large creches as we have done in the past two years. And recently the Bog has seemed devoid of juvenile Stonechats entirely so there has already been a dispersal into the surrounding countryside.

So we’d welcome any reports of our birds from both Dersinghan Bog and elsewhere. If the right leg sports a colour ring combination of either metal over dark green or metal over dark blue, it’s one of ours! We’d love to hear where and when they were seen, what the colour ring combinations are and any photos would be very welcome.

So to sum up our season as a whole, we colour-ringed 48 chicks and with a minimum of 3 chicks to add from the nest we missed, that makes a grand total of 51 chicks for this year. A few years ago we’d have been very happy with that total and we can only hope that a mild winter this year allows a good survival rate for our juveniles and we see the return of both existing territory holders next spring and hopefully the occupation of new territories by new birds.

Long Ponds from Foxhole_001With the help of our dedicated volunteers, we’ll be monitoring the winter occupation of the Stonechat territories on Dersingham Bog and searching for them in surrounding areas such as Snettisham and Roydon. A pattern was beginning to develop over the past few years of some territory holders staying on the reserve all year round, with others leaving and their place being taken during the winter by new pairs. These new pairs were then being ousted by the returning territory holders and we were seeing the establishment of completely new pairs on either existing or new territories.

So this winter holds plenty of interest and fingers crossed for a mild winter in preparation for an exciting 2019 breeding season.

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Our matriach’s legacy…

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.

Piezos SC 1st brood 2018-JasonThe 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.

Piezos 3rd brood SC 2017Other 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.

SC juv Henry PageAnd 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.

Piezos-SC 2nd brood nest 20180_001It’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.

 

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Round two

Round two of the Stonechat breeding season on Natural England’s Dersingham Bog NNR for 2018 can probably be summed up as having a sting in the tail…

In the end, only 5 pairs out of 6 produced a second brood and one of those pairs was technically already on a 3rd brood after a 1st brood failure. The timing of this female’s incubation suggested that she had got herself back into breeding condition while still helping to feed her newly fledged young, had built a 3rd nest and laid eggs within 10 days of her 2nd brood fledging… which is very fast, even by Stonechat standards.Triangle - SC 2nd nest 20181

We’ve ringed a total of 44 chicks from our first and second broods. In the early years of the project, we’d have been more than happy with such a total but having had two years of very high numbers (95 and 113, respectively), we haven’t quite got out of that expectation and so this is tinged with a slight disappointment.  

SC Triangle chick - dark blue cr combo2Our first 2nd brood chicks were ringed in early June and the last 2nd brood young were ringed at the end of June. But at least the brood sizes have been healthy on round two, with 4, 6 and 5 respectively, and with 5 chicks from our early 3rd brood pair. We’ve also switched to our new base colour, metal over dark blue, having used up all our dark green combinations.  

The nests of two of the Stonechat pairs were only found at the point where the chicks were being fed, so we ended up finding the nest and ringing them at the same time. This is never ideal as we like to find the nests when they’re at the egg stage, partly as it’s often easier to see bright blue eggs shining up at you from inside a thick heather bush but also that it allows us to better plan volunteer time. If we don’t find a nest area until food is going in, it becomes fairly urgent to find the nest as we’ve no idea how old the chicks will be and they may be at the ringing stage already, as it proved with these two pairs.

Snettisham Coastal Park 9-7-184The weather during the past couple of months has perhaps at least helped all our breeding birds feed both themselves and their broods more easily, even while the rest of us despaired at the lack of rain and worried over the fire risk to both the reserve and the surrounding countryside. A fire at the nearby Snettisham coastal park which destroyed both valuable habitat for both breeding birds and passage migrants did nothing to calm nerves. 

Piezos SC 2nd nest 20180Our Stonechat nests have continued to be in a mix of habitats and in a range of situations – 1 was in low heather right by a busy path, 1 placed right on the ground in low heather but well off the path, 1 high on a slope in very sparse heather with bare ground nearby, and 1 about 20ft off the main path but in the most amazing tunnel in dead bracken we’ve ever seen in well over 100 nests. That one took a great deal of effort to find and it was eventually found with the efforts of 4 volunteers and only then by Roger lying flat on the floor with his long arms buried to shoulder depth in a clump of dead bracken before he found the nest cup – the chicks could not have seen daylight the entire time they were in the nest!

SC male Tranquil valley unringed1Sadly, the empty territories we started the season with continue to be empty and it also appears that one of our Stonechat females is now missing in action. That pair, which arrived last of all at the start of the season, successfully fledged their first brood of 4 and there was no reason to believe they wouldn’t try for a second brood. However, after seeing the young gradually drift away from the territory, we had intermittent sightings of the female but saw nothing as decisive and helpful as a feeding circuit which would indicate she was on eggs. And now she appears to have vanished entirely and the male is on his own and just loafing about. He’s exhibiting none of the territory defence or activity you’d expect to see if he had a female incubating somewhere and now appears to be in moult, which means it’s game over for this breeding season for him.

Juv Stonechat1Another Stonechat pair which we thought were missing have now reappeared in another part of their territory… and with a fledged brood of unringed juveniles in tow, so we’ve missed a nest entirely! This pair were our first to nest up on the plateau and their first brood fledged in early May. Since then, we’ve failed to find any evidence of a second nest and it’s entirely possible we may have missed a second brood failure. We had some desultory nest building taking place a few weeks ago but nothing came of it and we’d almost decided that pair had also vanished until their reappearance this week. As annoying as it is to have missed a brood (which may technically be their third attempt), it is heartening that we can add at least 3 more juveniles to our overall total for the season.

As we began with very depleted numbers of only 6 pairs on the reserve at the start of the season, we can ill afford to lose any more pairs now. And as timings are very late in general with our nesting attempts, it remains to be seen if any of our remaining Stonechat pairs go on to attempt a 3rd brood.

TP Phils Heath 1st nest fledged 0_001Dersingham Bog’s other iconic breeding birds have experienced mixed fortunes. Several of our usually occupied Tree Pipit territories remained empty and we had only four pairs of Tree Pipits which managed first broods – two of those we found the nests and monitored success. But we failed to find the nests of the other two Tree Pipit pairs, although we were able to at least confirm breeding when we saw food carrying and fledged young.

WL Sheperds 1st brood 2018_001One Woodlark pair had two successful broods and although the other usual Woodlark territories have been occupied, proving breeding has been more difficult than usual this year. All the singing Woodlark males, which we hoped indicated that second broods were imminent in June, didn’t really materialise into anything and those pairs appeared to melt away. So the overall picture there remained unclear.

NJ Bryants East 2nd brood 20181The big success of the summer has been our Nightjars and it’s no exaggeration to say it’s been the year of the Nightjar on Dersingham Bog NNR. Somewhat to our surprise, territory occupation and the numbers of nests for 1st and 2nd broods has been very high. Given we thought Nightjars might have been affected on their migration as much as other species appear to have been and therefore we’d be down on numbers this year, it’s been very heartening that the exact opposite has proved to be the case. We’ve had amazing numbers… the highest number of churring males we’ve had for more than a decade (currently at 25) and the number of nests found so far stands at an amazing 22.

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Knock-on effects…

TP 1st brood Phils Heath 2018_001During the course of ringing some of the first brood Stonechat chicks, we noticed that several broods were slow in development. Some chicks which were technically a week old hadn’t developed as much as expected given their age. So it seems that some pairs have had difficulty finding enough food for their young, even though these were only fairly small broods, some with only 2 or 3 chicks. We also had more than our usual share of unhatched eggs this time round – several broods have had between 1 to 3 unhatched eggs.

March 2018In theory, the adults should have had an easier time finding food to feed their young on Dersingham Bog so far. We have fewer pairs this year and some territories which were divided into as many as three new territories last year are now occupied by only one pair. So there should have been less pressure on the overall food supply, so we’ve assumed that the winter weather has also impacted our insect survival rates.

Without empirical data, we’re left with speculation,  but possible causes could be:

  • As the adults presumably approached the breeding season in poor condition after the late winter weather, this, in turn, may have affected their ability to provision their young. But this could also be more complex than the cold snap directly affecting the parents’ ability to put on weight. Poor body condition of any species tends to lead to other complications, such as a higher predisposition to pathogens or parasites.
  • Galloway cattleTaking a very different example, the Galloway cattle on the reserve suffered a higher incidence of mites this year than they have before (probably due to cold conditions forcing down body weight and confinement in close proximity – they didn’t wander too far from their food). This meant they started the season in poor body condition and have taken quite a while to regain it.
  • View from Phils HeathReduced prey abundance due to winter / spring conditions – there are always winners and losers as a result of adverse weather. This partly relates to phenology of the species in relation to prevailing weather at a particular point of their lifecycle. The cold snap occurring when it did may have impacted on the early season invertebrate prey of the Stonechats. Whilst species that emerged later may not have been affected, those coming out around the time of the cold snap may well be showing depressed numbers. It needs more time to confirm this but it appears that the cold weather has reduced the numbers of heather beetle and it’s conceivable that this may provide a significant part of the Stonechat’s diet in spring.
  • Or, there could be a myriad other causes. Recent vegetation quadrat surveys at Scolt, compared to photos of the plots from the previous year, showed a change in structure (almost certainly related to the weather). This could have massive implications for nest site selection and predation risk, thus increasing the need for more adult vigilance at the possible expense of time spent feeding.

SC-Happy Valley - Les BunyanAnother indication of the impact of the winter weather on our Stonechat population has been a comparison of the number of ringed birds from last year to this. So far we have only 4 ringed birds, with the remaining 8 Stonechats on territory being unringed. This compares with last year when we had 25 ringed adults holding territory during the breeding season. And of those 4 ringed Stonechats this season, only 2 are territory holders from last year. Both these ringed birds spent the winter off the reserve, so wherever they ended up, fortunately they somehow survived the bad weather to return to the same territories for SC juv Henry Pagethis season.

It’s only been a couple of years of monitoring winter occupation and site fidelity  so it’s too early to draw any firm conclusions but a rough pattern was emerging of considerable site faithfulness. So we can only assume that the rest of those 23 ringed birds from last year may not have survived the winter. Certainly, of the Stonechats which occupied the reserve during the winter, none remained through the bad weather and into the spring so the losses may have been considerable.

On a practical note, we’re experiencing the same survey difficulties we’ve had in the past when the majority of our birds were unringed. With some core territories being close together, it makes it trickier for our volunteers to be sure which Stonechats they’re seeing. We’ve certainly been spoiled in the past with so many ringed birds on the reserve making it easier to ID birds.

So far our core territories are the only ones which are occupied and large territories, which had divided into 3 territories last year with the arrival of new pairs, are now back to being one extensive territory. So, hopefully, that will help with food supply for the pairs and chicks. How and if the situation changes for second and third broods remains to be seen… but we’ll keep you posted!

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Off the starting blocks…

SC male Tranquil valley unringed2Round one of the Stonechat breeding season on Dersingham Bog for 2018 can probably be summed up as… less than we hoped but more than we feared.

After the late blast of winter weather, we headed into spring with just 5 pairs of Stonechats on territory but we’ve managed to boost that to 6, with one pair arriving nearly a month later than usual. This was way below last year’s total of 13 pairs but given that some areas of Norfolk have reported a complete wipeout of their Stonechat numbers, we’ve been very lucky.

Happy Valley SC 1st brood nest 2018_001

Stonechat 1st brood nest

All our pairs have been staggered in their breeding timings as well, with some still on eggs while others were already feeding chicks. This at least meant it was easier to plan our volunteer effort and any bad weather striking the reserve didn’t hit all the pairs at a vulnerable time and cause big losses, which happened last season with our first broods when May’s bad weather wiped out 50% of our first broods.

 

Piezos SC 1st brood nest 2018_001Our total number of chicks from first broods this year was just 18. Our first chicks were ringed at the beginning of May and our 6th pair’s first brood ringed at the end of that month, with the chicks from the other pairs ringed at roughly weekly intervals in between.

Our first pair to nest produced only 2 chicks but laid 5 eggs, which seems to be a common occurrence on this particular territory. Given that this is the third pair to nest on this heath, it’s curious that each time the different females have laid 5 eggs but only 2 have hatched and subsequently fledged. Our next brood on another territory produced 3 chicks but only 2 fledged, with the runt dying in the nest.

SC Triangle 1st brood 20180 (2)

Stonechat brood near fledging

Fortunately, this was followed by a healthy brood of 5 chicks from a regularly occupied territory, and then 4 chicks from another core territory. Our first brood failure was of 4 chicks which were predated from the nest before they were ringed but the final pair which arrived late managed to produce 4 chicks.

 

Even with these reduced numbers, we’ve managed to use up almost all our dark green colour-ringed combinations and we’ve switched now to dark blue for the rest of this season.

Bryants TP 1st brood nest 20182_001We’ve also been quite lucky with the weather so far this spring. Whilst we’ve had spells of cold northerly winds and sometimes foggy conditions, we haven’t had prolonged or heavy spells of rain, and this has also been balanced with very warm settled spells of sunshine and light winds. Sometimes we seem to have experienced both winter and summer within the same week.

Piezos SC 1st brood 2018-Jason

Stonechat 1st brood nest deep in bracken

The nests have been in a mixture of habitats – 4 in heather, 1 in bracken and 1 in a mixture of sparse heather in a grass tussock, and the range of nest sites chosen has been equally varied. 4 have been right on the floor, 1 high and deep in a tunnel in dead bracken, and 1 well hidden in the middle of a substantial heather bush.

 

As our successful pairs start their second nests, the pair which experienced a first brood failure have already nested again, the female building another nest within a week. She laid 6 eggs and 5 healthy chicks were ringed this week.

 

 

Roger - Bryant's_001So over the next couple of weeks, we can hopefully see the remaining 5 pairs beginning to incubate their second broods and our volunteers will be busy nest finding, as well as keeping an eye on the currently empty territories to see if any new pairs sneak in.

Other areas of Norfolk seem equally affected by low Stonechat numbers. While there are 2 pairs in Snettisham Coastal Park and 1 pair on Scolt Head Island, our volunteers haven’t found Stonechat pairs in areas where they’ve bred regularly over the past few years, such as Brancaster, Thornham, the Drift, Dersingham, and Hunstanton Golf Course and we hear reports of other areas of the Norfolk coast being similarly affected.

TP - Phils Heath 1st brood 2018 0 (2)

Tree Pipit 1st brood nest

For our other Bog specialties the breeding picture is mixed. Our Tree Pipits only have 4 territories occupied this year, with 2 nests found so far. More worryingly, 4 other Tree Pipit territories which are nearly always occupied remain empty. Our Tree Pipits were also late arriving back and it seems to have been a similar picture with other summer migrants, both on the reserve and elsewhere either late arriving or not arriving at all. Other reserves and birders are reporting late arrivals or low numbers of summer migrants like Whinchat, Garden Warbler and Reed Warbler. Presumably the storms in Europe during migration have impacted how many have been able to return?

Nightjar survey work has only just begun so we should gain a clearer picture of their numbers soon but so far we have 4 nests with 3 other females found.

WL Sheperds 1st brood 2018_001

Woodlark 1st brood near fledging

With our Woodlarks, 1 pair produced 4 young and 2 other territories seemed occupied in early spring but although no first nests were found, those males are now singing again so we can assume second brood attempts are imminent. Interestingly, 2 territories which we thought were empty early in the season are now occupied. So whether this is a late occupation or they’ve managed to get first broods off under our noses isn’t clear.

The timing for our Stonechat breeding attempts has also been affected, with most of the first broods being several weeks later than usual compared to previous years. We can confidently expect each pair to attempt a second brood but how many go on to make a third breeding attempt remains to be seen.

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