Using Drones for Finding and Monitoring Nests

In recent years improvements in drone technology, and their increased affordability, has meant they have become a familiar part of modern life, with widespread use of drones for many purposes. This has included their use for recording wildlife, with all the benefits this can offer – but it is important that this is done responsibly. There is a dearth of guidance on nest recording with drones, including on rare breeding bird species, so we are delighted that experienced drone user Andy Harmer has shared his expertise in this blog on nest recording.

Long-eared Owl (Andy Harmer)

INTRODUCTION

Drones, or Uncrewed Aerial Vehicles (UAVs), are remote-controlled aircraft that are usually equipped with various sensors. They fly using rotating rotors that create lift. Most drones have four rotors, spinning in alternate directions to keep the drone stable. They also have a ‘central flight controller’ which maintains stability and controls speed.

On acquiring my first drone in the summer of 2016, I travelled around the county of Cheshire photographing landscape features from the air. I was immediately impressed by the simplicity of controlling the machine and comforted with the knowledge that if I panicked and took my hands off the controls, the drone would simply maintain its position in the air until my thumbs instructed otherwise. In the event of pilot or remote-control failure, signal loss or battery depletion, the drone would simply navigate safely to the location it took off from (Homepoint) and land.

Jumping forward to 2018, I received a request from Professor David Norman for me to use my drone to help with the Heronries Census, and though this activity would take me out of my comfort zone, I accepted the challenge but was worried about the accuracy of the count and the potentially adverse reactions of the target species. My concerns were immediately dismissed as the drone hovered over the reedbed heronry without a single sitting bird leaving its nest. Most birds did not react, but those that did simply put their heads on one side to view the strange buzzing apparatus (the result of this can be read in British Birds, Norman et al. (2022)). The camera provides a live stream to the controller and has the option for the pilot to record photographs and video in different formats. The photographs and video taken provided real evidence of nest occupation, spread, proximity, habitat-type etc.

It is probably prudent at this moment to simply generalise regarding the legislation as drone law is constantly in flux and undergone frequent changes. Suffice it to say that in simple terms, the bigger the drone, the stricter the rules are.

THE AVIATION REGULATOR (UK)

The Civil Aviation Authority (CAA) oversees drone operations and has established guidelines to ensure safety and privacy.

Key rules include:

  • Never fly more than 120m (400ft) above the surface
  • Always keep your drone in sight
  • Never fly in an airport’s Flight Restriction Zone (or a prison’s FRZ) unless you have permission
  • Almost all drones need to be registered, with requirements depending on the weight of the drone and whether it has a camera (drones with a camera that weigh over 100g require registration).

More detailed information on where drones can be flown can be found here.

Of particular relevance to the use of drones in nest-recording, the guidelines also state:

The full current drone code can be downloaded from here.

The CAA control the air space, and the drone code outlines where drones can and can’t be flown. There are apps and websites that provide maps showing where flights are restricted:

Website – https://www.noflydrones.co.uk

Altitude Angel app – https://www.altitudeangel.com/solutions/applications

BREEDING BIRD WELFARE, AND THE LAW

Of course, all fieldwork activity in the breeding season should aim to keep disturbance to breeding birds to a minimum, and this applies to the use of drones for finding and monitoring nests. As described below, drone use can help to reduce disturbance compared to conventional nest-finding and visiting methods, but it is important that drone users minimise disturbance. For example, BTO guidance for drone use in the Heronries Census states (1) You should fly at as high a height as possible in order to obtain adequate images to count occupied nests whilst remaining within the drone code rules; (2) Should you observe any signs of disturbance, you should stop the flight immediately.

In the UK, Schedule 1 birds (see Schedule 1 species list) are specially protected under the Wildlife & Countryside Act 1981 and the Wildlife (NI) order of 1985. This means that it is an offence to intentionally or recklessly disturb these birds whilst they are building a nest, or are in, on or near a nest containing eggs or young; or to disturb dependent young even if not in the nest. As such, any fieldwork that may cause disturbance to Schedule 1 species (even in instances where they are not the target species for monitoring) must be done under licence from the relevant issuing authority.

Guidance on applying for licences for nest recording of Schedule 1 species can be found here.

A DJI Mini Pro 3 (ZLEA)

THE EQUIPMENT

My two drone workhorses currently are the DJI Mini Pro 3 and the DJI Matrice 4T (Thermal).

DJI Mini Pro 3

This is a small hand-sized lightweight drone weighing around 249 grams. Its small frame, manoeuvrability and quieter operating noise makes this a great option for inspecting nests in both the urban and rural environment. These drones have less restrictive legislation than drones over 250 grams; the pilot being able to fly the drone closer to people and buildings, and over them without extra certification (although a Flyer ID is required for any drone over 100 grams, as well as an Operator ID if it has a camera). These are excellent for weaving between branches, around built structures such as bridges, viaducts, industrial units, and pylons etc. Portability is an attractive feature for the DJI mini, folding into such a small space that it enables the user to take it along just in case an opportunity arises, something you couldn’t really do with the heavier and more cumbersome drones.

The reader might be wondering why any other drone would be required after such a stellar review, but drones with extra weight have greater stability, better wind resistance, and a larger payload which can mean a bigger battery for longer sorties, more sensors, and better optics.

DJI Matrice 4T (Thermal)

In simple terms, the weight is the single most important factor for determining as to whether the drone can be lawfully flown in a particular location, with the safety of uninvolved persons being the main issue. As such, this larger drone, weighing just over a kilo, can only be used in areas where a distance can be maintained from uninvolved people, buildings, vessels, and vehicles, based on the potential of humans emerging from them.

The tech on this drone is impressive, especially in the optics department. As well as having multiple optical cameras with zoom facility, it has a thermal sensor, and a laser that can be used for stabilising the optics and measuring distances and altitude of the area that it is viewing, which helps in mapping and pinpointing nests in a 3D setting.

FEATURES AND BENEFITS

Aerial View: Viewing a subject from the air that is invisible from the ground is an obvious advantage for monitoring wildlife. The ability to fly the drone up to a height of 400 feet enables a much larger area to be scanned.

Thermal Imaging: Thermal imaging works by using an infrared or thermal sensor which picks up heat signatures. This heat data is converted to an image that shows the differentials in temperature with colour contrast. The temperature parameters can be altered to suit different birds and different environments.

Access: Drone surveys have different access issues than terrestrial surveys. Drones provide increased opportunity to survey areas which may be difficult to reach on foot, as they can bypass challenging terrain, muddy paths, flooded fields, cattle etc. However, landowner permission is still required for take-off and landing, and overflight may be restricted in various ways (e.g. Flight Restriction Zones, local byelaws, SSSIs) that might not affect a terrestrial survey in the same location.

Real-time Data Transmission: Taken for granted now but there was a time when a video camera on a pole, or for some, a kite, would film and be viewed once retrieved.

Autonomous Flight: Drone pilots can set the flight path of the drone along a transect. The drone will fly autonomously and will return after completing the task or if the battery needs changing. This can be used, say, for photographing large areas of arable land to detect Lapwing. An option for this type of coverage is that analysis of the images can then be shared between multiple people.

Reduced Disturbance: Disturbance can be reduced in multiple ways by using a drone, most obviously by reducing the number and proximity of humans in the survey area, by reducing duration of the task, and reducing the disturbance to habitat, which in turn lessens the chance of animals including humans spotting a trail to a nest.

Precision: High-resolution cameras, laser, GPS and thermal sensors on drones provide detailed data, allowing researchers to identify and map the smallest of nests. Recently I had the unenviable task of locating a skylark nest in a ten-hectare field that had only indicated ‘probable’ breeding status. Within ten minutes, the drone managed to detect a recently fledged Skylark metres from its nest.

Enhanced Safety: A good example of a drone enhancing safety measures is the way that it can eliminate unnecessary climbs (e.g. of trees or cliffs) by using it to check on nest contents. Climbing can be risky and unnecessary climbs can tire a valuable member of the team, which in turn may impact on his/her safety on later climbs. Using the drone to monitor the progress of ringers/researchers in a habitat such as a reedbed and guiding them safely to a nest will create a much safer working environment for them.

Increased Productivity: There are instances where the use of a drone cannot really expedite nest checking, such as when inspecting owl boxes, however, the hundreds of trees, miles of hedgerow, and hectares of fields/reedbed/scrub that can be searched in an hour or two of drone flying simply can’t be matched by conventional methods.

Evidence-based Results: I am certainly prejudiced by my own shortcomings regarding evidence. My memory, eyesight and hearing probably would score seven out of ten at best. The evidence collected by the drone gives a much greater confidence level to survey results and allows me and others to check for errors.

Ringer visiting a Marsh Harrier nest (Andy Harmer)

HEALTH AND SAFETY

It hopefully will not be a surprise that the attention to detail regarding the safety and wellbeing of the target species is similarly applied to the ringer/climber. Reedbeds, for example, can be dangerous habitats, so an assessment of the route to be taken and likely depths and obstacles encountered must be made. A typical reedbed ringing session will have the drone pilot hover the drone over and behind the nest to guide the ringers to it. The drone will be lowered to give greater accuracy as the ringers get closer to the nest. As a drone inspection will have been carried out prior to the ringers entering the reedbed, the number of pulli present will be known and any deficit upon arrival will be tracked down by the drone pilot who will then hover the drone over and slightly behind the absconder (s).

The images above shows a Marsh Harrier nest in the centre of a reedbed, and ringer Steve Binney at the nest after the drone had guided him to it. The reeds can be so tall that landmarks can’t be used as a guide to the nest. Steve had to look to the drone regularly to keep heading in the right direction.

PRACTICAL USE

Urban Gulls

Not all, but most, of our largest, noisiest, and most obvious birds in our towns and cities have historically gone under the radar when it comes to breeding records. This changed with the advent of affordable drones. In 2022, 87 factory and warehouse roofs across Cheshire were inspected and a total of 1250 breeding pairs of Lesser Black-backed Gull, Herring Gull, and Great Black-backed Gull were located. In short, this new piece of flying tech had enabled an incredible 62,400% increase in breeding records in Cheshire from these species in a year.

Lesser Black-backed Gull on a Warrington rooftop (Andy Harmer)

Thermal Imaging

The SBS (side by side) photographs below show low resolution images, and this is how it can be displayed on the screen of the remote control. The red hotspots clearly show a contrast in temperatures.

Though difficult to see in the normal optical view, the thermal image clearly shows nine heron nests (Andy Harmer)

Even at 400 feet the drone can show the heat of a Marsh Harrier on its nest (Andy Harmer)

Hobby hunting is more productive on breezy days when moving foliage exposes the heat source (Andy Harmer)

Eggs can show up well using the thermal camera, as can be seen with this Kestrel’s nest (Andy Harmer)

Large Nests

Corvid nests, Buzzard nests and Marsh Harrier nests are usually the easiest to find. The heat signature of all active nests tends to increase as the breeding season progresses, and the nest contents grow (in number and size).

It follows that a Corvid’s nest may be just as obvious whoever the tenant is, but the later nesters will benefit from less exposure as the canopy thickens and closes over. Corvid nests are often re-used by other species, with some late-breeders such as Hobby doing so in the same year.

Common Buzzard at the nest (Andy Harmer)

Marsh Harrier chicks in the nest (Andy Harmer)

Indicators

Drones can also be used to gather evidence that birds are nesting nearby. This could be a sighting of an adult bird in a suitable habitat, or even a pair, maybe white splash on a branch, post etc. One unexpected indicator was the almost luminous green circle of water in a reed bed. This had resulted from the projectile pooping of chicks enriching the immediate surroundings with nutrients enabling algae to thrive.

Winter is a good time for prepping for the coming season, and what better time to map corvid nests while the deciduous trees and bushes have lost their foliage. Long-eared Owl, Kestrel, Sparrowhawk and Buzzard were all found in corvid nests last season. The DJI Matrice 4T laser rangefinder is perfect for such a task, as each nest can have a ‘pin’ attached to the location calculating its precise location including its height from the ground. These pins are retained within the memory and will display on the remote-control screen. Each nest can be revisited by manually flying the drone to the nest, or the drone can be flown on ‘automatic’ and will take up the exact location that it was in when the pin was created pointing towards the nest from the exact same angle. All the pinned locations can be exported on a KML file to be used in a mapping programme such as Google Earth.

An inspection of an Oak tree revealed a heat signature that revealed a Little Owl (Andy Harmer)

This Hobby was observed perching on an Alder, its nest being found shortly after in an adjacent tree (Andy Harmer)

Anyone with an interest in phenology can track the cyclic occurrences in nature but this tends to have a bias of firsts rather than lasts; first Bluebell, first catkin, first bud burst, first Willow Warbler song of the spring, first Cuckoo, first Hobby etc, but I noted things ending such as the foliage life-support system causing defoliation enabling the locating of nests to become easier. A suite of trees compete for the last clad title; Ash tends to be the first tree to start losing its leaves, some bare by the end of October, followed closely behind by Balsam Poplars and Crack Willow. The Broad-leaved Lime, being more visible as a town tree, is not far behind, whereas English Oak and Birch are stubborn and hang onto their leaves even in the most ferocious of storms. Horse Chestnut tends to do a good impression of a tree that is shedding its leaves when in fact it initially looks barer simply because the leaves lose their moisture and often curl, enabling the viewer to see daylight through the tree. As the leaves fall, the nests appear, though there is no guarantee of further usage.

The above image illustrates how pins can be used to permanently record nest locations. These can be updated as the season progresses and exported to Google Earth as a KML file.

DRONE PROTOCOL

Although the literature on nest photography/recording by drone is now quite significant, there is still a lack of published official guidance on the subject. It was obvious to me that my requests for help from government bodies and bird organisations were not being ignored purposefully, they were simply rattling around the departments until they ran out of energy. It was quite clear that if I wanted a drone protocol, I had to create one.

I have prepared this protocol below as a reminder to myself but if any other drone pilot finds it useful, feel free to use it.

  1. Check what permissions might be required for the take-off site, and the flight route, and ensure these are in place.
  2. Undertake any appropriate preparatory work for each nest, or colony of nests, to assess the viability of flying a drone for the purpose of recording nest contents. The Drone Code as outlined by the Civil Aviation Authority must be considered first, followed by a localised assessment that will consider any likely impact to SSSI’s and other designated wildlife sites. The proximity to power lines, roads, houses, bridleways should be noted and if a nocturnal flight is to be made, reconnaissance in daylight should be undertaken. Before each flight, pre-flight checks should be conducted away from sensitive species and areas to ensure the drone is functioning as expected.
  3. As highlighted previously, have the appropriate Schedule 1 licences in place for the birds that are likely to be encountered, and be aware that other birds may be nesting that require permits too. If you’re looking for Marsh Harrier within a large reedbed, what’s the likelihood of Bittern, or even Spoonbill?
  4. The use of an observer to accompany the pilot when flying is encouraged and may be required in the presence of sensitive species to monitor for any signs of disturbance. Note that disturbance behaviours may include increased vigilance, flushing, alarm calling, attack, and more. If disturbance behaviours are observed, the UAV should be withdrawn, and the flight should be paused. If birds continue to demonstrate agitated behaviour, the flight should be suspended for the day. An observer can also help with H & S issues, such as looking out for and dealing with members of the public while the pilot concentrates on flying.
  5. Have clear objectives and without rushing, undertake the work in as short as time as possible, maximising the opportunity to record data whilst minimising disturbance to the birds. To minimise disturbance, take-off and landing should be at least 100 metres from sensitive areas. Flights should maintain 100 metres distance from birds where possible, and proposals to fly closer should seek advice. Where possible, species specific advice on minimum distances should be considered. Note that these safety limits may mean that some (lower-resolution) drone cameras will not be able to deliver high quality imagery at precautionary ranges.
  6. Bear in mind that any activity around a nest has the potential of drawing unfavourable attention, which may ultimately compromise the safety of the birds and nest contents, so timing of the visit must be considered carefully and if the risk is too great, then a flight should be cancelled, indefinitely if necessary. Birds are more susceptible to disturbance early in the nesting cycle, so avoid flying during these times.
  7. Use low-noise rotors when possible. This may increase flying time fractionally because of the slight decrease in efficiency of the blades, but the benefit of a quieter flight is that the birds are less likely to react adversely, and it may lessen the chance of a curious human hearing it. A slow flight mode should be used as this will limit any unintentional jerkiness with the flight. Abrupt movements with acceleration/braking appears to cause agitation in some birds.
  8. Assess weather conditions prior to drone use and during it. This will avoid unnecessary chilling or soaking of eggs/young/nest should a bird be put up off a nest. Exposure to the spring sun is usually less of an issue but bear in mind that drone use is more likely to be undertaken in areas that are more exposed, and updraft may be present near cliff edges.
  9. Avoid flying the drone directly between the bird and the sun. Most birds appear comfortable when a drone is visible and easy for them to monitor. Avoid vertical (i.e., descending from above) and head-on approaches as these resemble predator behaviour.
  10. Flying directly over nesting birds should be avoided. This is an unnecessary risk and though a complete motor failure on a modern drone is rare, it is prudent to have the drone to one side of the nest whilst photographing, or between nests when photographing a colony. The real-time video feed to a controller enables accurate positioning.
  11. Make the data available so it can feed into much larger information-gathering exercises such as the Nest Recording Scheme and of course the Rare Breeding Birds Panel.
  12. When a drone is used to assist nest monitors and ringers in a potentially dangerous habitat such as a reedbed, their safety is of paramount importance. A separate risk-assessment should be undertaken, and a system of communication agreed and adhered to. Ensure that you are equipped with enough spare batteries to enable drone flight for the duration of the exercise.
  13. Be prepared to be approached by a member of public whilst you’re flying a drone and have a response ready that will not compromise any nest location.

RBBP ADDENDUM

The Rare Breeding Birds Panel would like to thank Andy Harmer for providing this very valuable overview and guidance in what is a relatively new topic, and a subject for which clear guidance is somewhat hard to find! It is clear that in some instances drones offer considerable advantages over traditional fieldwork approaches for finding and monitoring nests, both in improving results and in decreasing disturbance caused during fieldwork. However, it is vital that drone users follow the guidance from the Civil Aviation Authority (and are aware of changes in that guidance), as well as any additional guidance that might arise from statutory nature conservation bodies, and organisations such as the RSPB and BTO.

For example, the RSPB stipulate on their website that ‘Use of personal or commercial drones on or over RSPB-owned property is not permitted unless specifically granted by the site manager for relevant use’, while National Trust state that “As a landowner, the National Trust does not permit unauthorised drone operation on its land and or properties”. The Wildlife Trusts have similar policies, such as those for Kent, Essex and Sussex.

We would reiterate Andy’s comments about minimising disturbance to breeding birds, and the need for appropriate licences when disturbance to Schedule 1 species is a possibility. Note that the Schedule 1 species list does not extend to all rare and sensitive species covered by the RBBP; we would recommend that all species covered by the RBBP are treated as if they were listed on Schedule 1.

In addition, drone users should consider the need for third-party insurance, which is currently optional for non-commercial drone use. The BTO have issued guidance on the use of drones for the Heronries Census which clarifies that BTO’s third party liability covering volunteers may not currently cover the use of drones for surveys so states “Therefore, Heronries Census volunteers should not use drones to carry out Heronries Census counts unless they have their own third party liability cover and have checked and confirmed that it will cover them if they use their drone for the Census.”

As yet, there is not a complete understanding of the impact of drones on birds, but a growing number of studies have been published, and do indicate that drone disturbance can lead to adverse impacts on breeding birds. For those wanting to read further, these papers might provide useful starting points:

  • Vas et al. 2015 suggested some ethical guidelines to reduce disturbance.
  • Afridi et al. 2025, Brisson-Curadeau et al. 2024 and Cantu de Leija et al. 2023 have all conducted meta-analyses of published studies. Variables such as drone height, distance between the drone and the bird, drone speed, drone noise level, bird breeding status, nesting behaviour and species size all were found to effect the likelihood of an impact on birds, with those impacts including increased vigilance, flight responses, or physiological stress.
  • Spaulding et al. 2024 provide an overview of actual and potential impacts on and benefits when using drones to study raptors and concludes by highlighting lessons learned and potential guidelines for use.
  • Edney et al. 2023. do likewise for the use of drones for seabird monitoring.
  • Werber & Hatzofe 2025 have recently published a guide to Drone use for raptor conservation and monitoring applications.

Drone photo of an incubating Sparrowhawk (Andy Harmer)

References

Afridi, S., Laporte-Devylder, L., Maalouf, G., Kline, J. M., Penny, S. G., Hlebowicz, K. & Lundquist, U. P. S. (2025). Impact of drone disturbances on wildlife: A review. Drones, 9(4), 311.

Brisson-Curadeau, É., Lacombe, R., Gousy-Leblanc, M., Poirier, V., Jackson, L., Petalas, C., Miranda, E., Eby, A., Baak, J., Léandri-Breton, D.-J., Choy, E., Legros, J., Tranze-Drabinia, E. & Elliott, K.H. (2025). A meta-analysis of the impact of drones on birds. Front Ecol Environ, 23: e2809. https://doi.org/10.1002/fee.2809

Brisson-Curadeau, É., Bird, D., Burke, C., Fifield, D.A., Pace, P., Sherley, R.B. & Elliott, K.H. (2017). Seabird species vary in behavioural response to drone census. Scientific Reports, 7(1), 1-9.

Cantu de Leija, A., Mirzadi, R. E., Randall, J. M., Portmann, M. D. Mueller, E. J. & Gawlik, D. E. (2023). A meta-analysis of disturbance caused by drones on nesting birds. Journal of Field Ornithology, 94(2):3. https://doi.org/10.5751/JFO-00259-940203

Edney, A.J., Hart, T., Jessopp, M.J., Banks, A., Clarke, L.E., Cugniere, L., Elliot, K.H., Juarez Martinez, I., Kilcoyne, A., Murphy, M., Nager, R.G., Ratcliffe, N., Thompson, D.L., Ward, R.M. & Wood, M.J. (2023). Best practices for using drones in seabird monitoring and research. Marine Ornithology, 51(2), 265-280. http://doi.org/10.5038/2074-1235.51.2.1544

Hodgson, J.C. & Koh, L.P. (2016) Best practice for minimising unmanned aerial vehicle disturbance to wildlife in biological field research. Current Biology, 26 (10), R404–R405.

Mulero-Pazmany, M., Jenni-Eiermann, S., Strebel, N., Sattler, T., Negro, J.J., Tablado, Z. (2017). Unmanned aircraft systems as a new source of disturbance for wildlife: A systematic review. PLoS ONE, 12(6): e0178448. https://doi.org/10.1371/journal.pone.0178448

Norman, D., Castell, R., Harmer, A. & Marchant, J. (2022) Grey Herons nesting among Bulrush. British Birds, 115: 452–455.

Spaulding, R., Gallego-Garcia, D & Bird, D.M. 2024. Conservation Letter: The Use of Drones in Raptor Research. Journal of Raptor Research, 58(4), 535-546. https://doi.org/10.3356/jrr2427

Vas, E., Lescroël, A., Duriez, O., et al. 2015. Approaching birds with drones: first experiments and ethical guidelines. Biol Lett-UK 11: 20140754.

Werber, Y. & Hatzofe, O. 2025. Drone use for raptor conservation and monitoring applications: review and best practices. Israeli Nature and Park Authority, Israel. https://raptors.cms.int/publication/drone-use-raptor-conservation-and-monitoring-applications-review-and-best-practices