Goshawk – Survey Methodology
GOSHAWK – SURVEY METHODOLOGY
Introduction
The methodology is adapted from ‘Raptors: a field guide for surveys and monitoring’ as well as other survey protocols. The interventionist nature of traditional survey techniques such as broadcast calling and visits to occupied nests are illegal under the Wildlife and Countryside Act without a Schedule 1 licence and are therefore not available to us.
Methods such as listening for adult territorial calls, plus those of fledged young from a safe distance, searching for signs of occupation prior to the breeding season and recently used nests after juvenile dispersal, as well as watching for displaying pairs and visible fledged young from outside the wood, would seem to be effective and practical alternatives, provided areas are accessible. Given the necessary restrictions imposed by not having a Schedule 1 licence, a combination of the steps below should maximise our chances of being as effective as we can.
The Goshawk Year
Breeding Activity(may be earlier in the south) / Peak Period / Range
(cold wet springs can delay laying) / Duration (days)
Occupation of home range / All year
Territorial display / mid-February to April
Nest building / Late Feb to mid April / September to late April
Egg laying / Early April / Mid-March to early May / 3 to 12
Incubation / Early April to mid-May / Mid-March to early June / 35 to 39
Hatching / Mid-May / Mid-April to mid-June
Young in nest / Mid-May to early July / Mid-April to late July / 38 to 46
Fledging / Late May to late July
Juvenile dispersal / June to early August / 20-40 days post fledging
Survey season visit schedule
1)late autumn / early winter – check for signs of occupation
2)February to early April – listen for adult territorial calls
3)February to April – check for displaying birds
4) July to September – listen / watch for fledged young and check for evidence of used nests
Survey techniques
Detecting signs of occupation early in the season will help to suggest appropriate locations for listening for calls and the best vantage points for display. Searchingfor signs will also help to judge the suitability of each wood for Goshawk, as some areas have not proved to be as promising as they first appeared, for a varietyof reasons (such as densityof trees and levels of disturbance).If no signs and / or calls are recorded but display is seen, that should reveal the best area to check for fledged young and search for used nests later in the season.
A combination of all four techniques should provide a reasonably detailed picture of territory occupation. Realistically, not all the woods will be accessible anyway, so some steps of even the adapted methodology may be not possible.
If time permits, two or more visits would be preferable for each area for each survey stage. More detailed notes are available if required on recognising Goshawk signs of occupation, calls, display, recently active nests, habitat, breeding characteristics, plus recordings and feather photographs.
1. Signs of occupation – late autumn / early winter
The most obvious sign may be the nest, but other signs of occupation include: droppings, prey remains, plucking posts, pellets, feeding perches, roosts, feathers. Please note the location and grid reference, particularly of nest sites.
Collecting any Goshawk feathers would also be useful as feather patterns can be unique to an individual bird. Signs of an occupied nesting area in the autumn may indicate a nesting attempt in that year, although it’s more difficult to detect signs when any understorey growth is high.
2. Adult calls – February to early April
Listening for adult calls at dawn from a suitable distance is viewed as an effective technique for monitoring known or suspected nest areas, particularly where previous sightings or signs have suggested occupancy. There is a lower risk of disturbance through this eavesdropping on natural behaviour rather than attempting to force a response to an external stimulus such as broadcasting calls.
However, it’s unclear how useful this technique may be in checking areas of potential habitat where Goshawk status is unknown, as the maximum practical distance for detecting calls is uncertain and the size of area which can be covered by each ‘listen’ is limited.
If no signs are found during earlier searching, it will be a matter of guesswork to pick a suitable spot, while at the same time staying far enough away to minimise disturbance. Several ‘listens’ may be necessary to narrow down the most likely areas. This technique may grow in effectiveness over the years as signs and display results help to narrow down probable occupied areas.
Goshawks are very vocal during periods of nest building, copulation and prey delivery in the months leading up to egg-laying, particularly in the 2-3 hours around dawn. Goshawks can begin vocalisation 30-45 minutes before dawn and continue for 90 minutes or more thereafter. Coverage by several observers stationed approx 200m apart is very useful in covering larger areas in one visit. In favourable weather conditions, it may be possible to hear calls 1km away in more open areas, as adult calls are strong and strident, but more practically they may be heard from up to 250-500m away.
Care should be taken not to approach the suspected nest area too closely. Stand at the edge of suitable habitat at least 300m from any known or suspected nest area. Two sessions a month apart with no calls should be sufficient to class an area as unoccupied. However, if only a single bird is present, vocalisation may be much reduced.
Please take into account any logistical problems in accessing areas safely before dawn; certain areas may be more awkward anyway. Visits before dawn to some areas of Sandringham, for instance, may attract unwelcome attention! Let me know if you need copies of Goshawk recordings, or any of the confusion species.
3. Display – February to April
High circling displays can be observed throughout the year but can be seen more intensely over or close to the nesting area during March to April. Display can start from mid February, particularly in fine weather, and can be seen from early morning.
Neighbouring pairs often cross boundaries of adjacent pairs so care is needed to separate territories. The ‘plunge’ at the end of a display seems to be a more reliable indicator that the wood in question might be a nesting area. However, even intensive display doesn’t always indicate an occupied nest site, especially if only single birds are seen; so as much detail on the birds involved and the type of display is helpful.
4. Listen / watch for fledged young and check for recently used nests – July to September
Disturbance of dependent young is covered under Schedule 1 so it’s not possible to search for occupied nests. Listening for the calls of fledged young from the edge of the suspected nest area at a suitable distance may be a low disturbance method for checking proof of breeding, provided the area is accessible.
It’s unclear how visible fledged young can be outside or over the nesting wood. This year the young of the Symonds Yat pair were frequentlyseen hunting and perched in trees; so although this is not a traditional technique for proving breeding for Goshawk, scanning from vantage pointsin July/August may be worthwhile, especially if the nesting wood has been identified with afair degree of confidence.(It would also be good to evaluate if this is an effective technique to use). If young are seen and heard, then it may also obviate the need to search for used nests and risk any form of disturbance.
If necessary, after the time when the young are most likely to have dispersed, it should be possible to check for the recently used nest with minimum disturbance. As hatching dates will be unknown, calculating when this will be is difficult. The earlier listening and any additional watching may help to decide an appropriate time to begin searching for signs of used nests when nothing can be heard or seen from outside the immediate nesting area. We must err on the side of caution; it would be preferable to miss the young entirely than risk any disturbance.
The young remain within 300m of the nest for 2 to 3 weeks after fledging, gradually moving further away from the nesting area, until dispersing 65-90 days after hatching but they can usually still be recorded up to 1000m from the nest.
If anyone finds evidence of an occupied territory from steps 1-3, but may not have time to check for calling / visible young or a used nest, please let me know so coverage can be organised.
Records
It would be helpful to record as much information as possible on the survey form. This will help to ensure that sites given limited coverage in one year can be targeted more effectively in future, and nil records are equally important.
Exact grid references, particularly for nesting areas and displaying birds, are very helpful in order to keep track of territory occupation each year and help target future survey effort.
Detailed records will be kept confidential within the circle of volunteers. Spreadsheet records will be submitted each year to the County Recorders, the Rare Birds Breeding Panel and NarVOS where appropriate, plus entered on Bird Track and the Bird Atlas. Let me know if you also submit your own records to any of the above so I can make a note on the spreadsheet.
Forms
One form per site per year for all the stages is hopefully the simplest method of recording results. Individual forms for each stage are also available if only part of the survey is possible. A spreadsheet version is available if that format is preferred, or you can send a more narrative email but please include as much of the requested information as possible.
It would be helpful if completed forms could be sent to me by the end of September / October.
Confidentiality
Please keep information on nest sites, known or suspected territories confidential (password protecting any completed forms). It’s essential that records of territories and news of the survey itself are not shared inappropriately.
Disturbance
Goshawk are fully protected as a Schedule 1 bird, which makes it illegal to cause intentional disturbance during nest building, near a nest containing eggs and young, as well as disturbance to dependent young. Effectively, a nest site is protected from the time of nest building until young have dispersed from the nest area.
Goshawk are particularly sensitive during egg-laying and early incubation and are prone to desert if disturbed at this time. New guidance on safe distances has recently been issued by SNH and for Goshawk the recommended safe distance from which to observe a nesting site during the breeding season is 300-500m.
If you are successful in detecting signs of occupation and display is seen in the same area, then it’s particularly important not to approach this area too closely again until after the young have fledged, and preferably moved further away from the nest area.
Persecution
Goshawks are still subject to illegal killing, as well as being at risk from deliberate disturbance and eggers. So please be circumspect when discussing what you’re looking for should you be approached by anyone. If you discover or witness anything suspicious, for any raptor, please report as much detail as possible to the local PWCO (Police Wildlife Crime Officer 0845 456 4567).
Permission
Please ensure that you have appropriate permission from landowners to enter private land / woodland. Not all landowners may welcome the presence of Goshawk on their land, so it may not be in the best interests of the species to advertise that you’re surveying for Goshawk, although it would be unusual if gamekeepers were not already aware of their presence. If permission to enter private land is not forthcoming, please keep to public footpaths or open access areas.
Other species
Another bonus of carrying out this survey should be the discovery of the presence and breeding of other raptors. It would be helpful if such records could also be submitted where appropriate.
Summary
This first year will be very much a trial to see if the suggested survey steps are effective. We can review what worked and what didn’t to ensure we make the best use of everyone’s time and effort for future years. I’d very much welcome feedback and suggestions on any changes and improvements.
References:
Bibby, C.J., et al Bird Census Techniques: second edition
Brown, R., Ferguson, J., Lawrence, M., Lees, D. Tracks and signs of the birds of Britain and Europe. Helm second edition
Cieslak, M., Bolestaw, D. Feathers: identification for bird conservation. Natura Publishing.
Etheridge, B. et al Raptors: a field guide for surveys and monitoring, second edition
Forsman, D., Solonen, Censusing breeding raptors in Southern Finland: methods and results.
Kenward, R.E. Goshawk, Poyser
Newton, I. The Sparrowhawk, Poyser
Ruddock, M., Whitfield, D.P. A review of disturbance distances in selected bird species. Report from Natural Research to Scottish National Heritage
RBBP Best Practice Guidance Notes leaflet
Woodbridge, B., Hargis, C.D USDA 2006. Northern Goshawk Inventory and Monitoring Technical Guide
The survey spreadsheet has been adapted from the spreadsheet used by the Scottish Raptor Monitoring Scheme (SRMS and is used with kind permission from Brian Etheridge, the Raptor Monitoring Officer (RMO) of the Scottish Raptor Study Groups (SRSG)
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