The following notes on finding Curlews’ nests were provided by several experienced field workers, in response to a request from Barry O’Donoghue of the Irish National Parks Service, as a contribution for the planning of the 2018 monitoring season. As noted by Barry, “Different regions and probably different sites will require tweaks to the methods used, I am sure, but the core principles will remain”:

Response from Phil Sheldrake, who monitors Curlews in south Wiltshire and in particular Salisbury Plain, dated 6 September 2017:

This is becoming quite a topic for discussion in our Southern Curlews Group, and I’m sure one of the suggestions at our forthcoming Forum meeting in October will be to produce some guidance notes.

My nest finding experience is largely borne out of years working with Stone Curlews – different habitats but the technique seems to work well for Curlews. There are some similarities and some differences with behaviour and of course, an understanding of those behavioural traits is best, and most rewardingly developed through experience. I’ve only done two years of Curlew survey and monitoring, so am only just starting to gain an interpretive insight to behaviour, so won’t attempt to describe in detail here. There are others who are eminently more knowledgeable and experienced in the art than I who I would seek to consult beforehand.

So, to offer a few ‘tips’ from my experience….

• Where and whenever possible surveying is most productive if done from a vehicle, preferably 4×4 with high ground clearance to enable access – you can get closer to the birds as the vehicle acts as a ‘hide’, so are less likely to disturb or affect behaviour. Stay within the vehicle and use a window mount for a telescope after scanning with binoculars to locate the birds. Typically, I like to be as far away as possible where I still have a good view of the birds and the area they are moving in (viewing across to an area that is sloping towards you is best). Best to be at least 100m away although you can get to within 50-100m with patience. Always withdraw if/when you get the sense you are influencing behaviour.
• Nest finding fieldwork on foot is not something I’ve done much, it’s not easy – you need to be much further away, and ideally concealed from view – Russell may be able to offer some advice as I believe surveyors in the New Forest may find on foot, or maybe Andy comes along in his truck?
• Working in pairs helps as one can keep the nest location in the scope while talking the other in by mobile phone.
• As you know, Curlew tend to be very site faithful so survey can usually be directed to established sites. Visiting early in the season should reveal a pair feeding together – in my limited experience usually less than 100m from where they end up nesting. On Salisbury Plain, where they tend to surface feed rather than probe, they seem to spend time preferentially foraging in areas of shorter sward and then nest in longer grass nearby.
• Pairs may be seen copulating or ‘nest scraping’ – following each other closely and intently, occasionally sitting and doing the bum wiggle thing to create a ‘bowl’ in the grass – these are good indications that nesting is imminent and going to be ‘around there’.
• During laying of the clutch (usually one egg every 24-48 hours) I have found the pair generally tends to be in fairly close proximity, hanging around the area close to the nest – settling down to watch for a while you may see a bird have a quick ‘sit down’ – seeing this repeated in the same area can be a give-away for the nest location.
• When you see just one bird on a subsequent visit, chances are the partner is sitting. Just wait and watch for a changeover is the best give away. Early in incubation I have found the off-duty bird tends to stay fairly close to the nest location. Using the telescope to search/keep an eye on the area near to the bird, looking for a head, possibly just visible, possibly occasionally just popping up to look round can reveal the sitting bird – I have found nests by seeing what looks like ‘horizontal’ grass, which is actually the bill!
• Seeing a changeover is always a YES! Moment. This is the best method of finding a nest, but it can take a long time. Watch the area where you have previously seen birds or where you have seen a single foraging bird. An imminent changeover is usually indicated by seeing the off-duty bird change its behaviour, usually foraging stops and the bird adopts a directional purpose – walking slowly, with great awareness towards the nest when the sitting bird will reveal itself by standing up, although you’ll probably have seen its head or the ‘horizontal grass’ before. Of course both birds may be found ‘off-duty’ and one eventually returns in this manner. Quite possibly, your arrival may have put the sitting bird off, and as long as you’re not too close, ‘watching back’ in is a good method – this will happen reasonably quickly if there’s a full clutch and you’re not causing a disturbance. Intentional disturbance and watching back is something I’ve done with Stone Curlew, we know it is a risk-free from experience. I’ve not done this yet with Eurasian Curlew and would be interested to know others’ thoughts on this approach?
• Again, in my limited experience, I have noticed that the off-duty bird tends to wander much further from the nest once incubation is on a full clutch, and the sitting bird sits much tighter – and increasingly so, to the point where I have checked on previously found nests later during the incubation period having not seen either the off-duty bird or sitting bird (grass growth) and found the bird happily sitting – I have approached to within 3-4m away and been able to take a photograph.
• First egg dates on Salisbury Plain in the last two years have been last week April/first week May, making the optimum nest finding period the second and third weeks of May, after then it gets increasingly difficult as the off-duty bird spends more time away from the nest area and the sitting bird sits tight.
• Time and patience in May is the key, be as far away as possible, watch and things will happen. I GPS all nests and mark discreetly, using short garden canes with black tape around the top so they blend into the landscape but can be seen through the scope. I also find it helps to mark where you’re viewing from and note the landscape features possibly by a little drawing in the notebook which help relocating your canes directionally on a subsequent visit when the grass has grown!
• This year I weighed and measured eggs to calculate hatch date using the formula in the Murray Grant paper (see under ‘Literature Library’ on this website). I weighed during laying and also noted date of complete clutch as a check. A small electronic weighing machine is essential to record weight accurately. Russell and the team in the New Forest have used data loggers this year which we hope to hear more about at the Forum meeting – particularly useful in conjunction with weighing and measuring.

Response from Andy Page, Head of Wildlife Management in the South England Forest District, who monitors Curlews in the New Forest, dated 12 September 2017:

Hi Barry

You have a very good and comprehensive reply from Phil about how to find Curlew nests and I would endorse all that he has said, particularly the usefulness of observing from a vehicle. Unfortunately this is not always possible and observations on foot must be made. I must admit that my time in the field is precious and waiting for a changeover can be lengthy and unpredictable and not something I do readily. Once I have a single bird where I was previously finding a pair, I favour walking the sitting bird off by moving around the territory until I see the pair again then sit down and observe. One important thing to stress is that of being far enough away when watching birds. With some Curlews, 100 metres can still be too close for them to be comfortable returning. Unless experienced in the subtleties of Curlew demeanour, nest finders will just get feeding behaviour when they could in fact be keeping a bird from returning to a nest. Recognising feeding and false feeding is of great benefit at this time. Birds will often walk off a nest unseen in front of the observer and when eventually spotted, the normal reaction is to stop and observe. Chances are that by this time you are in fact quite close to the nest and observations will just give you a feeding bird or birds. Curlews are generally very wary and will not normally return until they are satisfied that any potential threat is some distance away. Having said that, I have had birds sit so tight you nearly tread on them, so individuality and time of the incubation process can all play a part in how successful you are. Try to vary your watching point if you have no positive movement from a suspected nesting bird after, say, 20 minutes. If unsuccessful and returning another day, it is often productive to approach the suspected nest site from a different angle if at all possible, while looking intently for any bird moving away in front of you. They are also very good at running obliquely to your line of approach when they leave the nest rather than straight away from you, making location of the actual nest more difficult. Cumulative observations, even from some distance but where the adults can see you, can affect their behaviour and be misleading to even experienced nest finders. “Banking” your observations and coming back fresh another day can often pay dividends. If I am sure a nest is close and I cannot find it within 10 -15 minutes of close searching, then I will also abandon the nest finding attempt till another day rather than repeat the disturbance again. On a following day, a swift walk straight to the suspected nest area will usually reveal the sitting bird walking off. Always try and approach a suspected nest area from a blind spot or where the sitting bird has the most restricted vision. Where birds can see you approaching from hundreds of metres away they will often have walked off the nest well before you are anywhere near close enough to see them. I do however appreciate that this may not be possible in some circumstances. As with all species, stage of the nesting cycle, terrain, weather, and individual peculiarities all come into play so there is no hard and fast rule for finding nests. Most important is observing the subtle nuances of individual behaviour to tease out the information you need to find the nest. Birds are no different to humans in their posture and actions when they are relaxed or uneasy and recognising these will save many wasted hours of fieldwork.

Response from Mike Smart, who monitors Curlews in the Severn and Avon Vales, dated 14 September 2017:

Hi Barry

Herewith some additional thoughts from southwest England.

We unfortunately don’t have access to a vehicle when searching for Curlew nests, so have to do it on foot. In general, I have simply stood with a telescope, either behind a hedge or, in a large field, a long way from the likely nesting site, and simply keeping very still.

In our area, the birds are nesting in large hay fields where nests are very difficult to find, especially when the grass grows a bit – it’s often too high for comfortable nest finding by late April, and mid-May (as suggested by Phil) would be pretty near impossible for us. So we start pretty early. With us, most birds return to nesting fields by mid-February or early March; since we know they are highly site-faithful, we can predict with a fair degree of certainty which fields they will use. They tend to occupy these fields early, just walking about in pairs: ‘just walking about’ may not sound very much of an activity, but in fact, it’s pretty significant, and a sign that they are holding territory. If you watch for some time, you will very likely see them carrying out courtship chases; after walking round in a quiet rather stately manner, one bird will start chasing the other for a short time (I’m not sure who chases whom, it’s not necessarily the male chasing the female), the male sometimes holding his wings vertical, with quivering wingtips, sometimes uttering a distinctive guttural wail; one of the birds will often resort to ‘false feeding’ as mentioned by Andy – they pick at the ground on either side, sometimes taking a small ball of dead grass and throwing it over their shoulder. All this, to me, is a good indication that they intend to nest, and is most likely in our area to happen in March, when the grass is still blessedly short; observation time in March or early April is never wasted; by May the grass is often too long for you to see anything (that’s where a high vehicle would come in useful!). Observation of the birds’ behaviour later on in the season will often confirm that the pair is nesting: as noted by Phil and Barry, you start seeing a single bird (rather than the pair) on guard duty, and they go quiet in May when they are on eggs. When the chicks hatch, the agitated behaviour of the parents, with barking alarm calls, is a sure sign of breeding.

In the past, we have tended to think that it is not necessary to find the actual nest: nests are difficult to find in very large hayfields, there is a risk of damaging hay crops on private farmers’ fields, and above all, there is a huge risk of opening the way to the nest for predators like foxes, badgers and crows; I would hesitate to the disturb the birds by weighing eggs, knowing (from trying to approach them closely to colour read rings) just how nervous a bird Curlew is; I would fear desertion of the nest. Better perhaps to wait until the end of the season, and see whether the chicks succeed in fledging and flying? You can be sure that there was a breeding pair by the behaviour of the adults. On the other hand, use of nest loggers (not only in Shropshire and the New Forest – see Newsletter 3 – but in the Upper Thames too) has provided really valuable insights on whether the nest is being constantly incubated, and on if and when the nest is predated; use of electric fencing in Shropshire and the Upper Thames to protect nests from ground predators also appears to give better productivity; so we may in future devote greater attention to nest finding.

So, lots to discuss at our forthcoming meeting in Slimbridge in October, and beyond. As you say, best to start preparation for the 2018 monitoring season now, and to get those temperature loggers, electric fences and 4×4 vehicles ordered straight away!