A Hat-trick & a Century

After the high failure rate of our first broods, a successful round two of nests, we were hopeful but unsure what any third breeding attempts would bring for our Stonechats. In previous years, we’ve had only a couple of pairs try for a third brood. This time, with so many failures on the first broods, we were more hopeful that more pairs would attempt another nest.

Once again the weather was kind to us for our third nesting attempts and with the timings of the pairs again spread out, any bad weather didn’t have a significant impact. So round three proved to be a mixture of pairs who attempted three nests and succeeded, while some pairs managed technically their second broods. In total, 9 pairs went for a third nesting attempt and we managed to ring 36 chicks. Once again, we missed one nest which fledged a minimum of 4 young, so we had a minimum of 40 young fledged from those 9 pairs.

Little Nose 100th chick 2017

Our 100th Stonechat chick for 2017!

So the big news for the project is that we crossed the century mark for the first time which was an amazing achievement, both for the birds and the volunteers. Ringing the 100th chick felt like quite a landmark and a cause for celebration. We didn’t quite wet the baby’s head but it was a close run thing…

 

In total over the whole season, we had found 33 nests, missed 2 more nests and ringed 113 chicks, with a further 8 chicks to add to the total from nests we missed. Considering that it was as recently as 2013 that we only had 2 pairs of Stonechats on Dersingham Bog, producing 10 chicks over a whole season, the increase in the population has been nothing short of remarkable.

In trying to sum up the various territories, this is where it gets complicated… Overall, 8 of our Stonechat pairs made three nesting attempts, with 6 of those pairs being successful. One of those pairs was remarkably prolific in terms of numbers, with 5 chicks from the first nest, 6 from the second and 4 from the third.

4 of our pairs nested twice, with 3 of those pairs successfully raising two broods and one pair failed on both of their nesting attempts. 3 territories held 5 pairs of Stonechats in total, 2 of those territories changing occupants partway through the season. Those 5 pairs made a single nesting attempt each and 3 out of the 5 pairs were successful.

Roger 2The territories where the occupants changed was a result of territories being abandoned by their original pairs after the first breeding attempt and later being replaced by new pairs. Curiously, one of those abandoned territories had been successful with a first nesting attempt so it was puzzling why the successful pair left. Those supposedly empty territories took everyone by surprise when they were reoccupied, with one of our volunteers literally making a chance discovery of a pair carrying food, but it shows the value of checking all the territories regularly. It perhaps also reflects the increasing numbers of Stonechats in the area now that suitable territories don’t remain empty for long during a breeding season. It’s a comforting thought that Dersingham Bog may now be a Stonechat nursery for the repopulation of West Norfolk.

It’s been a fascinating season and our Stonechats continue to be an absorbing, yet at times frustrating, species to study and our volunteers have put in a huge amount of time and effort to ensure we found as many nests as possible. It remains to be seen if next season will be just as busy and even if any more territories can be squeezed onto the reserve or whether we’ve reached our carrying capacity. We’re conscious a lot could depend on whether we experience a bad weather winter, for the first time in several years, which could have a significant impact on the numbers which return to breed. Our luck can’t hold forever.

IMG_20170712_143152546_HDRWe’ll attempt to monitor what Stonechats remain on the reserve through the winter as we did last year, to continue to build up a clearer picture of winter territory occupation. We’d very much welcome any reports of our dispersing Stonechats, both adults and juveniles, through the winter around Norfolk and perhaps beyond, as well as those which continue to occupy territories on Dersingham Bog. Meanwhile our volunteers, Roger and Irene, can probably be found recovering in a home for the bewildered through the winter… (aka the pub).

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Round two…

After our mixed Stonechat fortunes for our first nests, with more than a 50% failure rate, we were hoping that our second broods would fare better… and so it proved.

SC chicks almost ready to fledge

We still have 13 occupied territories and found 12 nests, with 11 successful broods ringed. We missed 1 nest entirely and 1 nest failed at the egg stage. 45 young were ringed, with an additional 4 or 5 extra unringed juveniles to add to the total from the brood we missed.

We had a mixture of brood sizes, with some very small broods of only 2 or 3 but we also had 3 broods of 6 young, which is the first time we’ve had pairs produce 6 eggs, let along fledge 6 young. One of those pairs had failed on their first brood but the second pair with 6 chicks had already produced a successful first brood of 5 young, so it’ll be interesting to see if they try again. Our third pair with 6 youngsters is a new pair occupying one of the previously abandoned territories. We also had several females lay 6 eggs but only between 2-4 hatched.

Our first nest with 6 eggs

The weather was a lot more settled for round two and simply because it was later in the breeding season, the temperatures were a lot warmer anyway even on rainy days. The only spells of bad weather didn’t last for long this time and a spell of very hot weather will have helped the availability of food.

The first brood failures resulted in the timings for the second nesting attempts being more spread out and the pairs were not as synced this time, so any bad weather did not affect all our pairs at once, as it did so disastrously before. The second nesting attempts have been so spread out that we’ve been ringing second broods on the same day as early third broods.

This staggered nesting has also allowed us to spread out our volunteer efforts. With limited time available for our two volunteers, it meant we could target our efforts more effectively as we had a good idea of the status of each of the territories and weren’t wasting time on ones which weren’t ‘ready’ yet. All of that, of course, was made possible by finding every first brood nest and monitoring its progress, which then unlocked the timings for the rest of the season.

The one failure was from a pair which failed first time round, also on eggs. This time it could have been to do with the location chosen for the nest – in low sparse heather with lots of bare ground around it. This pair may also have had an unfound failure as there was a very long gap between the first nest and the finding of their latest attempt, so it remains to be seen if they will try again. It’s a shame in a way as the male for this pair is our oldest  and previously most prolific male (white/orange), so maybe he’s chosen unwisely in his partner this year or maybe he’s firing blanks…

Our new pair’s chosen nest area

Two of the territories we thought were empty after first nest failures… weren’t! The original pair in one territory managed to raise a brood unnoticed right under our noses. The other empty territory has been re-occupied by a new pair; the male is one ousted from a neighbouring territory but the female is a completely new bird, not reported since she fledged last year. She was born in a second brood to our most prolific female so hopefully she has good genes!

We have no way of knowing where she’s been or whether she’s attempted to breed before, so this could be her first breeding attempt. Or perhaps she attempted elsewhere and failed? It’s perhaps unlikely she would have left a territory elsewhere if she’d been successful unless it was the loss of partner which triggered her move. Either way, she could try again.

As we gear up to monitor which of our territories will attempt third broods, our totals of fledged Stonechat young are looking a lot healthier, with 94 young ringed. So the question is, will we reach 100 chicks ringed for the first time in the project’s history? We missed it by a whisker last year, ending the year on 95 ringed young so we’re tantalisingly close already.

Posted in Colour-ringing project, Dersingham Bog, Stonechats

ABANDON SHIP…

After the poor weather which had such an impact on our pairs during their first nesting attempts, it’s looking increasingly likely a handful of our Stonechats are missing. Four of our occupied territories on Dersingham Bog are now a Stonechat free zone.

After the mixed fortunes of the first broods, with 8 failures and 7 successes, we’ve been monitoring all 15 occupied territories to try and establish when each pair might attempt a second brood, or a relay in the case of the failures. So far, three of the territories which failed may have been abandoned entirely by the pairs and another territory, which successfully fledged five juveniles, is also now empty.

It’s too soon to be absolutely sure as it can take quite a while to confirm a territory is definitely empty and it’s not just that the female is being typically elusive while she’s sitting, but in three of the territories, the males appear to have gone AWOL too. And if they are now empty territories, we’ll never know what happened… whether the pair just abandoned the territory after their failure and moved elsewhere to try again, or if they’ve ceased breeding altogether for this season, or whether one or both of the adults has been lost, either through the bad weather or predation or illness.

But we can be fairly sure that one male has lost his female. One of the Bryant’s Heath males has been singing and displaying to the two females on neighbouring territories, much to the annoyance of their current partners. This is also having a knock-on effect on one of the neighbouring territories where second brood young have just hatched. The distraction means that the territory male is not pulling his weight by taking in the usual share of the food to the chicks as he’s spending too much time chasing off the intruding male.

It’s a shame to see these empty territories after such a consistent occupation over several years and it’s particularly poignant that our longest occupied territory at the Piezos now appears empty. We can only hope that some of them may be reoccupied again at some point, perhaps during the autumn and winter with the dispersal of this year’s young. Or perhaps we have now reached carrying capacity for the reserve and what’s happened shows that 15 occupied territories may be too many for the available food on the Bog, particularly when bad weather strikes early in the season?

However, it’s not all doom and gloom. The other pairs, both the initial failures and our successful first broods, have been getting on with their second nests as expected. So we now have a satisfying mixture of incubating females and newly hatched young, including some where the fledged first brood juveniles are still hanging around while the female sits on a new clutch.

In fact, several females which failed first time round during the appalling weather were incubating barely 2-3 weeks after the initial failure, which just goes to show how quickly Stonechats can go down on eggs again. Even knowing how quick this species can be with second broods, it’s still remarkable when you consider the weather conditions at the time and the strain on the females. In one territory, a pair had been feeding young for a week before they were predated and yet the female then got back into condition, built another nest and laid six eggs, all within 2 weeks of the first failure.

So, as we move into the time for starting to ring the second broods and the weather has become more settled (until today!), it’s looking good for a more productive round two. Although as the rain lashes against the window, let’s hope that’s not tempting fate again…

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Round one to the weather…

After the spell of bad weather which scuppered five of our Stonechat nests, we had hoped that the conditions would relent enough to allow the rest of the first brood attempts to succeed. But once again, the weather had other ideas. The spell of bad weather at the end of April (covered in a previous blog) continued, with prolonged northerlies which resulted in more Stonechat broods going down like ninepins.

To sum up our 1st brood totals, we have 15 active territories and 33 chicks were ringed from 7 successful nests. By comparison, 44 chicks were produced from 12 nests for our 1st broods last year. We had 8 failures – 2 from predation, 3 failing on eggs and 3 at the chick stage, so more than a 50% failure rate, which is high for the Bog. While losses to predators are to be expected, the remainder of the failures were most likely down to the bad weather at the wrong time.

Most of our reserve is sheltered from the prevailing south westerly weather, which works in our favour most of the time. However, the entire length of the plateau is exposed to the north, so while we can usually ride out the odd spell of wind and rain from that direction, the fact that the northerlies lasted for a fortnight or more spelled disaster.

The high pressure system might have brought dry, warm weather to most of the country, but here in Norfolk it resulted in strong winds channelling down the North Sea, bringing bitterly cold conditions across the reserve. Inevitably, this suppressed the availability of insect food for both adults and their newly hatched young so the adults must have struggled to find enough food, not only themselves but their chicks. Some nests faced north and were in exposed spots on the plateaux, which can’t have helped.

As the male doesn’t incubate the eggs when the female comes off on a feeding circuit, the eggs are left uncovered. In inclement weather, the female must spend longer and longer off the eggs so eventually they chill too much and become unviable. Or her survival instinct kicks in and she has to abandon the nest in order to find enough food for her own survival.

Unsurprisingly, the pairs which succeeded have all nested in sheltered spots, although one pair was a surprise success. They nested on the ground in an exposed spot in a fairly obvious nest on a north facing slope – we’d have placed bets that it wouldn’t stand a chance but it produced 4 healthy young.

Until we start checking the territories for the second nesting attempts, we also won’t know if we’ve lost any of our females. We did last year during a similar bad weather event when we had a change of several partners, with ‘divorce, remarriage and house moves’ on some territories between the first and second broods.

We also can’t be sure how many of the fledged juveniles have survived the poor weather. Unusually, we’ve not seen many juveniles post-fledging so far. Hopefully, the parents have just taken their youngsters to more sheltered parts of their territories but it’s entirely possible that there have been other casualties, as the first few weeks out of the nest are a very vulnerable time for a small passerine reliant on insect food.

The timing of the bad weather and the length of time it lasted could not have come at a worse time, which is why small passerines play a numbers game and have at least two and sometimes three broods. The warmer weather of the last week or so will hopefully help not only the juveniles survive the first few weeks of life but allow the females to get back into condition again for another nesting attempt.

We’ve also been lucky that all our first brood nesting attempts were early this year. This time last year, we were still finding first brood nests in early to mid-May but all ours had gone down on eggs by mid-April, no doubt helped by the mild weather during March and April. So hopefully there is enough time now for those that failed to try again, hopefully twice. Certainly in previous years, those pairs which failed early went on to nest twice more in a season and mostly successfully.

So fingers crossed that the weather now settles into a warm spring… ready for round two!

 

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Does size really matter?

An interesting email exchange with John Furse prompted this blog post about the size of our Stonechat territories. As the Stonechat population at Dersingham Bog has increased, we’ve often speculated as to what seems to dictate the size of the territories themselves and the choice of boundaries.

With only a handful of Stonechat pairs until a couple of years ago, the territories were either very large or widely dispersed but as the reserve has hosted ever more Stonechats, the territory boundaries seem very much defined by the topography of the Bog rather than just the pure size of each territory. We’ve never been able to predict how big a Stonechat territory will be just by looking at acreage occupied – it’s always been defined by the layout of the habitat.

It’s a feature of Dersingham Bog that the habitat and topography can change in a relatively small area. Essentially, the reserve is almost on two levels, with the plateau extending the full length of the reserve and

Plateau, main track and mire

bordered on its northern side by the wetter mire, with the main footpath running through the middle. Dividing all that are various ridges or ‘noses’ – headlands extending out onto the mire which result in some valleys being closely bordered, giving a very sheltered and enclosed feel to some relatively small areas.

Two of those territories are long and narrow as a result of the topography rather than being squeezed in between other pairs. They are bounded on three sides by the plateau, so the territory has stretched out in a long rectangle onto the mire rather than spreading sideways as the plateau pairs do.

Three other territories have always been the largest, spanning areas which start up on the plateau and extend down the slopes and out onto the mire. But these territories have gradually been nibbled away this year with new pairs encroaching on the edges as it’s presumably harder to defend territories on separate levels.

Our oldest and most territorial male has always defended a very large territory. He has previously occupied an entire heath on the plateau, the slopes leading down to the area around the dragonfly pond, as well as a prominent ridge extending out into the mire and a large chunk of the mire itself. In the last year, two younger males have established territories on his boundaries, with one taking over the heath on the plateau and the other taking half of the mire area.

By contrast to other areas, this last part of the territory has very little in the way of defined features dividing it and the boundary line seems to be a cleared area halfway along the ridge. Both males have taken to patrolling back and forth either side of the clearing, displaying and posturing at one another like a couple of gunslingers!

Another male has also lost two portions of his territory this year. He once defended an extensive heather plateau, a gully, an area of mire and a low heather valley. It was always a difficult one to monitor to find nests as there are very few spots where you can see all of the territory from one place, so his territory defence must have been doubly difficult to maintain. This year, two new pairs have moved into the edges – one pair taking over the higher plateau, with another pair carving out part of the mire, leaving the original pair with roughly a third of the area they once occupied.

In another part of the reserve, what was one territory now holds three pairs and that area is unusual in that it’s large and flat, with no topographical features dividing up the ground. Feeding areas overlap but by and large, the birds stick to their boundaries.

The topography also defines how close territories may be to one another. Territories may be back to back either side of a ridge and technically within 50 metres of each other, but to all intents and purposes, they are hidden from neighbouring pairs so presumably the males don’t have to spend all their time on territory defence.

Some feeding areas on the boundaries do overlap, with pairs using the dividing ridges themselves, which the males tend to patrol as their boundary lines. As more pairs squeeze onto the reserve and existing territories are carved up into smaller chunks, presumably these shared feeding areas will increase as pairs seek enough food for themselves and their young.

So lots of food for thought, not least about how much of an impact does this territory carve up have on food availability for the pairs? Will we see an impact on productivity if it continues, especially if we get too bad weather events like last week during a breeding season?

It’s tempting to think that the overall boundaries of the Stonechat territories can’t be pushed out any further as the habitat shouldn’t be suitable. Currently, the only places on the reserve which are empty of Stonechait pairs are relatively small gaps right out on the mire, or up on one plateau which has very sparse heather cover at the moment as it was the last part of the reserve to be cleared of pines. However, the Stonechats have surprised us before with adopting areas we would have thought unsuitable so we’ve stopped making predictions!

Dersingham Bog has perhaps an unusual layout, the plateau being the line of an old sea cliff, with the mire occupying what was once the seashore. It can’t be a unique layout for a heathland reserve but it’s certainly unusual. So has the topography contributed towards helping the establishment of such a density of Stonechat territories? It would be interesting to discover how territories are divided up in reserves which share a similar topography to Dersingham Bog.

And our original and frequently asked question remains. Just what is the carrying capacity of Dersingham Bog? How many Stonechat territories can the reserve sustainably support?

Posted in Colour-ringing project, Dersingham Bog, Stonechats

Trials & Tribulations of Dersingham Bog

The weather this spring has been pretty kind to our Stonechats, with a high pressure system sitting on or close by for most of late March and April. This has allowed our birds to find suitable partners and territories, get down to nest making and start laying eggs. This also allowed us similar time to locate said territories and when we believed it safe to do so, to find the nests. Indeed, the weather was so benign that one pair was so far in advance of the norm that we nearly missed the young and the brood may have fledged before we had found it. Luckily, we got there in time.

So by 21st April, 14 nests had been located and the advanced nest youngsters rung. Of the 14 nests, two pairs were due to be rung, two had three-day old chicks and the rest were sitting tight on full clutches. All was looking good.

By our calculations, another visit on 25th April should have given us an opportunity to ring two pairs and check how the eggs were advancing for the other pairs. Wrong! Mother Nature decided to throw a spanner in the works and as strong winds with sleet, hail or even snow was forecast and unfortunately, duly arrived, we did not manage to visit until this morning, the 27th.

Although our two nests which we felt were ready for ringing had survived, the young were not as large as expected. Presumably the adults’ ability to find food must have inhibited their growth. Nevertheless, they were big enough and were suitably rung.

Another two nests had recently hatched and miraculously, the young were all alive, but of the remaining nests, four had failed at the egg stage. As we approached the nests, there was no alarming from the adults. Indeed, no adults were seen at all and it looked ominous. We presume that the female must have eventually been forced to think of her own survival and had abandoned the clutch.

Two of these nests were built on a plateau and would have been in direct line of a northerly blast and with no shelter from the rain. The other two are more mysterious, as the nest on ‘Piezos’, built by an experienced female, had been placed in a grass and bracken tussock facing away from the prevailing winds, although again with not much shelter from the rain. The other pair, again an experienced pair, had a full clutch of eggs on 8th April, so should have had young by now. So perhaps there’s another reason for the failure, which we can only speculate about.

So of our 14 nests, four pairs have been rung. Five are still with full clutches and we have five failures so far. But at least now we will have staggered nesting attempts with not all our eggs, literally, reliant on one weather window. So, barring any further weather problems, hopefully the second broods may not be so catastrophic.

Roger Q Skeen

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Shuffling the pack…

Having built up a fairly clear picture during the winter of which pairs were occupying which territories, including any new colour-ringed Stonechats arrivals, there were still some surprises as we moved into the start of the 2017 breeding season.

We’ve been lucky with another mostly mild winter this year and while the numbers of Stonechats on the reserve have fluctuated, there have been regular sightings throughout the autumn and winter periods on most of the territories. Our only spell of bad weather was in February, when there was a brief spell of around a fortnight where Dersingham Bog appeared virtually devoid of any Stonechats.

When birds started to return to the site during March, that’s when the main changes took place and the situation is still fluid as we move into April, with several new colour-ringed arrivals only this week.

CxFbofLWgAE3IK1Several territories which had been occupied during the winter by the same pair that bred successfully in 2016 now have completely new pairs, colour-ringed birds which hadn’t been reported elsewhere or on Dersingham Bog since they fledged last year.

Other territories have given a convincing rendition of musical chairs. Two females have moved to other territories on the reserve, ousting the existing pair or becoming the new partner to an existing territory holder. One female (from Ugly Dale) has taken over another territory, right at the other end of the Bog, far from where she nested last year. And the female from that territory (Tranquil Valley) can now be found just around the corner in her neighbouring territory (Piezos), which was previously held by our most prolific female. Confused yet?!

As mentioned in our most recent blog, 2 other territories which were empty throughout the winter are suddenly re-occupied, one being again held by the 2016 breeding pair. Where had they been through the winter? Had they wintered together somewhere or were now returning separately to the site?

Either way, it’s interesting that they returned to exactly the same territory. As that has been empty throughout the winter, maybe they didn’t have the territory battles when they arrived that might have occurring in other parts of the reserve?sc-fem-ltbw-landfill-w-20163

Interestingly, a new colour-ringed pair which occupied a new territory on Phil’s Heath through the winter have remained into this breeding season, and on the same spot so far. Another of the new territories established during the winter, which had a new 2016 colour-ringed male present, now has another new, previously unreported colour-ringed male, also from last year’s crop.

As we’ve said many times before, without colour-ringing, we wouldn’t have noticed these changes at all. So far, all 3 new territories established through the winter are still occupied, though not necessarily with the same ringed pair that set them up in the first place.

Our oldest male has remained on his territory all winter and is now preparing for a new breeding season with a new female, also from the 2016 crop. He has a particularly large territory, spanning an area up on plateau and extending down onto the mire, although corners are being nibbled away by new pairs. Last year, the northern boundary of his territory on the mire was occupied by a successful pair (the male of which has just returned to the same territory again after being absent all winter).

The other large corner of our oldest male’s territory now has at least one, possibly two pairs, carving out a chunk of ground for themselves. One pair established a territory on the periphery during the winter and seem to be still there, and another is a new colour-ringed male.
Unfortunately, our oldest female may have disappeared, as there is a new female from the neighbouring territory now occupying her territory, and with a new ringed male. If she isn’t re-found, it’ll be a sad loss but she has contributed significantly to subsequent generations since she started breeding in 2014. Her progeny have been scattered through the reserve over the last few years forming new successful pairs and establishing new territories.

One of the most interesting aspects of this shuffling of the pack has been how late it occurred. We hadn’t exactly become complacent by the end of the winter but we were confident we had a handle on who was where as we entered the new breeding season. So in the space of a few weeks, after our only spell of bad weather cleared the site, findimale-stonechat-from-keithng that many of the territories had changed was a bit of a surprise for the volunteers as yet another new colour-ringed Stonechat popped up somewhere new!

Is this typical? A late winter shuffle around occupying pairs? Or was it governed by the weather and the empty site, allowing early new arrivals to take over empty territories? So if we’d had the bad weather earlier in the winter, would the shake-up also have occurred earlier, but with another potential late winter / early spring change as birds wintering offsite returned to the Bog? As always, lots of fascinating and unanswerable questions keep arising with these charismatic birds.

It remains to be seen how many more new territories can be squeezed onto the reserve, or if the current state of play remains the same, or whether further changes will happen before they begin nesting. We’ve already had nest building taking place and given how synched many of our Stonechat pairs have been over the past few years, it won’t be long before most of our females are incubating their first broods, weather permitting.

 

Posted in Colour-ringing project, Dersingham Bog, Stonechats

Winter territory fidelity

For the first time in the course of the Stonechat project, this winter we attempted to gain a clearer picture of both site and territory fidelity by regular coverage of all the territories outside of the breeding season. We wanted to determine a number of things if we could.

How many of our ringed Stonechats remained on the reserve? How many of the existing territories were occupied during the winter and by whom? How many of our existing pairs would remain as they were or would new partnerships form, which would then continue into the spring? Would new pairs take over existing territories or establish new ones?

In other words, how much of a shake-up occurs each winter and does that picture change again by the next breeding season?

Each territory was visited at least once a fortnight, sometimes more often, by one of our volunteers. As the territories are spread fairly evenly throughout the reserve and the whole reserve was walked regularly, we’re pretty confident that most of the Bog was covered throughout the autumn and winter. Such regular coverage through another mostly mild winter has thrown up some interesting sightings and probably raised as many questions as it answered in terms of winter territory fidelity.

Photo – Roger Hancocks

Of the 13 active territories during the 2016 season, 8 were occupied consistently throughout the autumn/winter period; 3 more held Stonechat pairs intermittently and 2 territories appeared empty on every visit.

These two territories were both in areas where the conditions can be fairly harsh during winter; one is out on the mire and another suffers from a complete lack of sun in that part of the reserve in the winter. Interestingly, both those empty territories have now been reoccupied, one with exactly the same pair that bred successfully last season and who had been absent from the Bog all winter.

Of those 11 occupied winter territories, 4 were held by the same ringed pairs that bred in 2016; 2 other occupied territories held unringed pairs so we have no way of knowing if they’re the same birds; 5 other territories were held by one of the existing 2016 ringed pairs but with a new partner. This change of partners proved to be a mix of new males and females scattered throughout the reserve.

We’ve speculated previously on how many Stonechat territories can be squeezed onto Dersingham Bog and once again last year, we thought 13 territories must be fairly close to the reserve’s limit. But apparently no one has communicated that to our Stonechats!

During the course of the winter, it became clear that 3 new territories were being established. All were new arrivals and all were colour-ringed pairs from our 2016 broods and they carved out corners of existing larger territories. It will be interesting to see if those new pairs remain into the new breeding season or if it’ll be all change again.

Our two most prolific breeders, a male and female from separate territories and born in 2013, both have new partners from the 2016 broods. They’ve also both stayed throughout the winter on territories which they’ve occupied since 2014. Some of the new colour-ringed birds who arrived on the reserve during the winter have spent time on their natal territories, some with one parent. Some have established new territories in neighbouring areas to where they were born, or have taken over existing territories but again ‘next door’.

2016 female – Triangle territory

Once again all these observations and results have shown the value of colour-ringing. Without it, we’d have been unaware of all these changes and it would have been tempting to make the wrong assumption that any unringed pair staying from last year’s breeding season through the winter would be the same birds, and that they’d be the same territory holders staying into this year’s breeding season.

 

As it is, some territories have seen 3 separate pairs so far in the course of six months. And judging by observations by volunteers during the past week, it’s all change again. Some of the existing territories now have new colour-ringed pairs entirely, as a wave of new arrivals seems to have taken place, either ousting the winter pairs or mixing up the partners yet again.

As the 2017 season starts, it appears the picture of territory occupation is by no means settled… which deserves a blog entry of its own soon. And if anyone knows of any monitoring of winter territory or site fidelity for Stonechats in other parts of the UK, we’d be interested to hear their findings.

Posted in Colour-ringing project, Dersingham Bog, Stonechats

Near and far…

Some interesting sightings have emerged over recent weeks of some of our colour-ringed Stonechats, both near to their natal area at Dersingham Bog and the furthest sighting yet reported over in Suffolk. We’ve Tweeted about them already but it’s worth fleshing out the details a bit more, not least to acknowledge the Herculean efforts made by the observers to work out the eventual colour-ring combinations!

Richard Drew was kind enough to send details of a male Stonechat he’d seen on Westleton Heath which arrived at the beginning of March. This proved to be the furthest sighting yet of one of our Stonechat offspring from the Bog. To our knowledge, it hadn’t been reported since it fledged. Would love to know the journey it’s taken in between!

This male (yellow/white and grey/metal) was born in 2015 to our most prolific female (grey/orange and grey/metal) in her third brood of that year. At the time of Richard’s sighting, it was paired with a female so it’ll be interesting to see if it goes on to breed at Westleton. Our previous distance ‘record’ was a bird seen in Thetford Forest a few years ago, 40km away from Dersingham Bog.

Reports of another colour-ringed bird then came from Ray Roche, this time from Heacham, just north of the Snettisham Coastal Park area. It must have been a relatively newly arrived bird as that area is watched regularly by several birders. It was also a male which was born in 2016 as a first brood young to a territory occupied by our most prolific male (white/orange and grey/metal).

Trying to read the colour combination proved tricky as pale colours tend to ‘wash out’ in sunlight and can appear white, which is exacerbated sometimes on photographs. But thanks to Ray’s repeated visits, several extra pairs of eyes and photographs, it was eventually deciphered as pale blue/lilac and grey/metal. Again, this bird hasn’t been reported since it fledged last year and is currently paired with an unringed female. There’s also another unringed pair nearby so it’ll be interesting to see if those two pairs stay to breed in that area.

Many thanks to both Richard and Ray for the sightings and Ray for permission to use his photos.

We’ll be writing about the existing territory holders which stayed on site over the winter soon, as well as the new pairs establishing over the winter. We’ve also had some new colour-ringed birds returning to the Bog recently which have not been seen since they fledged so it may well be all change soon in terms of who is where…

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New kids on the block…

Over the last couple of weeks on Dersingham Bog, we’ve seen a mixture of existing Stonechat pairs remaining on their territories and a return of some of the 2016 juveniles to the reserve. Most of the crop of 95 juveniles from this season had vanished from the site by the autumn but now we’re seeing the return of some of them, 12 so far and it’s been a fairly even mix of males and females.

These Stonechats are now either muscling in on existing territories and replacing one of the 2016 partners, or they’ve been pairing off between themselves and have occupied existing currently empty territories or have set up new territories in completely new areas.

Both of our prolific breeders, both born in 2013, have new partners from this year’s crop of juveniles. Our most prolific male (white/orange), who has a territory in the centre of the reserve on Flat Nose, now has a new female (white/lilac and metal/grey). She was a third brood bird born in the neighbouring Piezos territory to our most productive female, (grey/orange and grey/metal)… that could be an interesting lineage / productivity with that pair if they survive the winter and stay together to breed next season.

And that same prolific female at the Piezos territory also has a new male partner (orange/yellow and grey/metal), who was also born this year in the first brood of a successful pair with a territory in Ugly Dale.

It makes for very confusing family trees but so far, of the 12 juveniles currently on the reserve, 3 are from 2016 broods from that same Piezos female. And 6 more can also be directly linked to her as, technically, they’re her grandchildren as the territories they were born in have one parent who was born to that Piezos female in 2015. She really is turning into the ‘matriarch’ of the Bog.

sc-female-piezos-3rd-brood-2016And at the risk of confusing everyone further… here’s one of her third brood young (red/lilac and metal/grey) from 2016, a female who is now setting up a territory on Phil’s Heath with a male (dark blue/light blue and metal/grey). He was also born this year in a territory where the adult male was born to the Piezos female in 2015… so does that make ‘grandson’ paired with an ‘aunt’? Anyone else confused yet?!

No doubt the winter weather will considerably diminish the numbers which stay on site or even survive the winter at all, and it could be all change by the time the 2017 breeding season comes around. We’ve been very lucky in the last couple of years that the winter weather has been so mild that it has no doubt contributed to a higher survival rate of the juveniles in both 2015 and 2016, as well as some continued occupation of territories throughout the winter, and has also maybe allowed early breeding by some pairs which have then gone on to attempt three nests in a season.

If we get a really bad winter this time, we could see a big slump in the same way Kelling Heath did a few years ago and Stonechat numbers could crash and we’ll be building up from low numbers again. Only time will tell…

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