Nest and chick monitoring 2024
Just as the first of our Shropshire curlews were arriving back on their breeding grounds in March, I performed my own annual migration from Norwich back to Curlew Country, taking advantage of the short grass to start surveying returning birds and identify them by their colour rings. This was a change of pace from the previous year, when I’d barely set my luggage down in my new accommodation before the phone started ringing (Tony had found the first nest of the year on 26th April, and I was straight off to fence it). It was great to see all the migrants arriving in sequence; I saw (what would be) my last flock of redwings shortly after arrival and though the chiffchaffs were already singing away, they were yet to be accompanied by their more mellifluous cousins – the willow, garden and wood warblers, lesser and greater whitethroats, etc. would join them later on.
Working on the Curlew Solutions Trial meant walking all the suitable habitat in our study area (three times!) during the pre-breeding season to locate birds and delineate territories. With the typical wet spring weather of Shropshire, trudging through waterlogged fields was quite a slog, and my blisters had blisters on their blisters by the time it was done. For a bird lover like myself, there were always exciting things to see, which helped me keep my feet moving through those long and soggy transects. I was lucky enough to see wheatears and ring ouzels on their passage through, as well as spotted and pied flycatchers, cuckoos, yellow wagtails and whinchats that had come here to breed. An unusual number of whimbrels (the pocket-sized cousin of the curlew) were keeping me on my toes towards the end of April and into May, feeding together in our usual curlew fields in flocks of up to twenty birds (likely kept in the UK for longer due to strong northerly winds impeding their passage to their breeding grounds in Iceland). Odder still was a summer-plumaged bar-tailed godwit which turned up in one of our regular curlew nest fields in April.
As usual, the nest finding commenced at the end of April when birds were just starting to lay. Since our headstarting licence had come to an end* and our resources were needed to provide data for a nationwide scheme, this year focused on finding and protecting nests with temporary electric fencing to boost hatch rates. I had spoken with Amanda and Tony the previous year about doing my master’s thesis work with Curlew Country and the year off from headstarting provided us with an opportunity to do some more comprehensive nest and brood monitoring of the wild birds for the Curlew Solutions Trial.
The first nest was found on 23rd April with four eggs, so slightly early for the study area, and would go on to hatch three chicks on our live streaming Curlew Cam. The second was found with one egg (still warm – presumed just laid) but was unfortunately found predated when we returned to fence the full clutch. Another fifteen nests were found and fenced subsequently (total sixteen), however three were predated anyway and more were lost for other reasons, leaving just eight nests that hatched in the end.
As usual, the nest finding commenced at the end of April when birds were just starting to lay. Since our headstarting licence had come to an end* and our resources were needed to provide data for a nationwide scheme, this year focused on finding and protecting nests with temporary electric fencing to boost hatch rates. I had spoken with Amanda and Tony the previous year about doing my master’s thesis work with Curlew Country and the year off from headstarting provided us with an opportunity to do some more comprehensive nest and brood monitoring of the wild birds for the Curlew Solutions Trial. The first nest was found on 23rd April with four eggs, so slightly early for the study area, and would go on to hatch three chicks on our live streaming Curlew Cam. The second was found with one egg (still warm – presumed just laid) but was unfortunately found predated when we returned to fence the full clutch. Another fifteen nests were found and fenced subsequently (total sixteen), however three were predated anyway and more were lost for other reasons, leaving just eight nests that hatched in the end.
The primary focus of my thesis work was to study the chicks in their habitat and measure brood survival relative to the vegetation structures present in these habitats. This meant revisiting broods once a day, as often as possible and recording the ground cover and brood use of different sward structures, until no chicks or chick-guarding adults were detected on three subsequent visits. While this started out being quite easy when I had just one brood to follow, it quickly snowballed as I was still monitoring and maintaining fences on active nests while more and more broods were added to the roster. While eight out of sixteen fenced nests hatching was a disappointing result in conservation terms, I think I’d have struggled to keep up with many more broods simultaneously, not to mention the emotional punch I felt with every lost brood, so it was perhaps better for my own mental health. I was particularly gutted to lose track of the Curlew Cam brood in their fifth week, just shy of their estimated fledging date. After watching them so closely throughout the incubation period and following them every day since then, this was a bitter pill to swallow. On the (sort of) upside, we were thrilled to see that the father of one of our fenced nests in the Stapeley area was in fact one of our headstarted birds and he would go on to raise his brood to over three weeks old (no mean feat for a curlew in Shropshire). Until he led his chicks out of the hayfield where they had nested, we had been unable to confirm the identity of either parent due to the length of the uncut hay. It was great to see a hand-reared bird doing exactly what it ought to be doing and along with the other less-welcome results of the season, has renewed my enthusiasm for headstarting curlews.
Disentangling the varying effects of vegetation height and use by broods was hampered by the small sample size of broods to study, but broods were significantly more likely to survive their second week if they utilised short (<20cm) vegetation. This has implications for land management strategies to improve fledging success for wild-reared curlew chicks, such as the incorporation of short swards in managed grassland, particularly in grass-crop systems (as opposed to grazed systems). Grass-crop systems are usually homogeneous in structure, which may impact brood survival via the mechanisms of reduced prey availability/foraging opportunities, difficulties with thermal regulation and movement through dense grass growth. The grazed systems used by broods in this study exhibited much more heterogeneity in the vegetation structure. Of the broods which survived beyond their second week, those which hatched in hay fields were led into grazed areas by the end of the first week, where they remained until broods failed in weeks 3-5.
Reflections on the season
For all our efforts in locating and protecting nests and tracking brood survival, no chicks were confirmed to have fledged in the study area. This closely mirrors results from field studies by Curlew Country conducted in 2015-17, which found that no chicks fledged from 30 nesting attempts followed. This illustrates the stark reality that while fencing can improve the hatch rates for curlews, this can be a wasted effort when large-scale landscape changes and the associated increased levels of predation prevent conversion of chicks to fledglings and new breeding adults. As curlew chicks are exponentially more likely to survive to fledge once they’ve survived the first week after hatching, the initial results that five broods had survived into their third week was encouraging and exceeded expectations (although the final outcomes were made that much more disappointing!).
*Curlew Country was the first organisation to successfully apply for a Natural England licence to ‘headstart’ in the UK, which it has done for six years releasing 149 chicks back into the landscape and has remained the only initiative to remain purely headstarting. Since then, several ‘translocation’ projects have started to operate under licence, either rescuing eggs from airfields or taking first clutch eggs from grouse moors and re-introducing the resulting chicks into new areas have. This has resulted in a new licence format which is more in tune with translocation activity of bigger organisations. Curlew Country hopes to obtain a new licence and is considering how best to qualify with the new requirements orientated toward translocation projects which do not fit with headstarting practice and objectives.