BTO - British Trust for Ornithology - Scotland

Songbird migration across the Sahara

WEBSITEEDITOR — Mon, 11 Jul 2022 11:49:47 +0000

Mark Wilson, BTO Research Ecologist, reflects on his work tagging songbirds to collect data about their migration routes and their breeding grounds in the UK. Yes

Mark Wilson

Acting Head of Science Scotland

Mark is responsible for developing and leading research and contributes to the scientific strategy of BTO Scotland. He manages a small and brilliant team of 3 research and fieldwork staff, and is involved in several BTO projects and external collaborations carrying out research and monitoring work on a wide range of topics including upland and woodland ecology, breeding waders, raptors and acoustic monitoring.

Bird Ringing Scheme

This Tree Pipit is one of dozens of birds that BTO colleagues and I have been fitting with miniaturised geolocator ‘backpacks’. From the information collected by these clever little tags, it’s possible to work out where the birds wearing them have gone.

As well as Tree Pipits, we are fitting tags to five other migratory species which breed in the UK but spend their winters in sub-Saharan Africa: Garden, Wood and Willow Warblers, Whinchats and Spotted Flycatchers. Of these, Wood Warblers and Whinchats are declining across the whole of their British ranges, while the rest are all declining in the south of Britain, but faring better in the north.

Our project has tagged birds of all six species, first in central and southern England, and now where I am based, in the hills, woods and gardens of central Scotland. We hope the results will reveal whether the migration ecologies of these birds could be contributing to recent declines, and maybe help us to understand the differing fortunes of northern and southern populations.

The sound of summer

Listen to the recordings we use in the field.

Tree Pipit

Willow Warbler

Wood Warbler

Whinchat

Garden Warbler

tree_pipit_graham_catley_bto_square.jpg

willow_warbler_allan_drewitt_bto_square.jpg

wood_warbler._edmund_fellowes_bto_square.jpg

whinchat_edmund_fellowes_bto_square.jpg

garden_warbler_jjohn_lowes_bto_square.jpg

Before a bird can be tagged, it must be caught. Once a mist net is up, we will put a portable audio speaker below it and play the songs and calls of one or more of the species we are trying to catch. By doing this, we simulate a territorial incursion by a rival male. The idea is that the resident male will fly over to the recording to check it out and be caught in the mist-net. When trying to catch Wood Warblers, the recording has sometimes been playing for less than a minute before the target bird is in the net!

Of course, it’s not always that straightforward. We are all familiar with differences between species in how they look, what they sound like, and where they live. But birds also differ from each other in their personalities.

Willow and Wood Warblers typically respond strongly and rapidly to playback, but Tree Pipits and Whinchats often display more caution. Our colleague John, who has worked on Whinchats for many years, estimates that it normally takes about 25 minutes to catch a Whinchat using a sound recording to lure it into a net. Oddly, Whinchats can show every sign of knowing a net is there, looking at it, flying around it, even perching on it – before eventually flying into it!

In comparison to the other species, Garden Warblers can be very difficult to catch, displaying even greater caution than Whinchats. A typical Garden Warbler may respond to playback not by charging in to check out who the intruder is, but by flying a short distance away and singing back to the tape from cover.

The trickiest of these species to catch in mist-nets, though, is the Spotted Flycatcher, due to their acute eyesight and phenomenal aerial agility. Most Spotted Flycatchers respond even less strongly to playback of their ‘song’ (a high-pitched, two-toned squeak that, at least to the human ear, sounds rather understated) than Garden Warblers do. To catch these birds, we rely on their well-known habit of repeatedly returning to favourite perches after flying off to catch insects. Accordingly, we catch Spotted Flycatchers using special ‘perch traps’, placed in what we judge to be tempting places for them to perch.

This Wood Warbler has been fitted with a unique combination of colour rings, which are visible with binoculars or even by eye. These allow fieldworkers to identify individual birds in the field, without needing to recapture them.

There can be almost as much variation in personality within a species as there is between species. Some Wood Warblers keep their distance from the simulated breach of their territories, staying high in the canopy, or respond to audio playback by flying away from it! Timing makes a difference, too. Most males are easier to catch early in the season, when they are defending newly established territories, striving to outdo their neighbours’ efforts to attract a female or even, once they have paired, jealously guarding fertile mates against the chance that an intruding male might convince her to be unfaithful. Later in the season, when their mates are incubating eggs, or when eggs have hatched and there are chicks to feed, many males seem (understandably) much less bothered at the prospect of a male, presumably late arriving and unpaired, belatedly trying to persuade their female into a liaison.

Once we’ve caught a bird that we are going to deploy a tag on, it’s all systems go! Keeping the time taken to ring, measure and tag the bird to a minimum reduces the amount of stress it experiences. As well as fitting a standard metal ring with a unique identification code on one leg (just as we would with any bird we ring), we also fit a unique combination of coloured plastic rings allowing individuals to be recognised in the field. We measure the weight of each bird, and the length of its wings and tarsi (the ‘leg’). Tagged birds are then fitted with a geolocator’ backpack’, attached via a pre-sized leg loop harness. We select which tag to deploy based on the size of the bird, checking that the fit is good before the bird is released. We monitor the birds closely throughout, only fitting tags when their stress levels remain relatively low. A portion of birds, referred to as ‘controls’, are left untagged. We fit colour rings to these control birds so we can compare the return rates of our tagged birds with those of untagged (but individually recognisable) birds.

Releasing a Whinchat Glen Finglas, the Trossachs

Many large remote-tracking devices transmit the data they collect remotely to researchers, without the tagged birds ever being seen again. However, smaller geolocator tags store all the information they collect ‘on board’. This means that in order to learn where tagged birds have gone, they must be recaptured on their return to us, so we can retrieve their backpacks. This year was the second year of this project in Scotland, and the first in which we have started to retrieve geolocators from tagged birds. Unfortunately, return rates seem to be lower than normal, and not many of last year’s tagged or control birds have been seen. The fact that the proportion of returned control birds is at least as low as that for tagged birds, as well as information from other sources such as BirdTrack, suggests that the low return rates aren’t being caused by the tags. Although this makes it harder to get many of the tags back, we do have some, and will keep trying to find and retrieve more. Every tag that we do retrieve can tell us lots about migration timings, routes and stops, as well as movements on the wintering grounds.

Without the generous help and support of all these volunteers, projects like this would be much harder.

This is a rewarding project to contribute to. Over the past two years, many people have generously contributed their skills, knowledge and, in the case of Spotted Flycatchers, gardens, in order to benefit this project. Going back to visit last year’s Spotted Flycatcher ‘hosts’, in whose gardens we caught birds, will be a particular pleasure this year. Without the generous help and support of all these volunteers, projects like this would be much harder.

Catching birds to tag them requires a lot of skill...and patience! Here, BTO Scotland's Research Officer, Anthony Wetherhill, waits for a Spotted Flycatcher to land on a perch trap.

During fieldwork, we found a Roe Deer fawn hiding in the bracken.

All of these species are special, and it is a privilege to work with them...it’s great to know that this project could help us to understand migrant declines and, more importantly, work out what we can do about them.

An added bonus of spending long hours doing pretty much any kind of fieldwork is that days are inevitably enriched with generous helpings of ‘non-target’ wildlife. During our fieldwork we’ve stumbled across Roe Deer fawns hiding in bracken, inadvertently flushed Black Grouse off a road onto the roof of a nearby cottage, found unexpected nests of Wood Warblers, Willow Warblers, Whinchat, Grey Wagtails and Snipe, come across Canada Goose goslings bimbling through a woodland for their first swim, watched an Osprey being mobbed by irate Common Gulls and viewed a White-tailed Eagle sailing over the hills. It’s occasionally been a great engagement opportunity too, with lucky walkers being greeted by a bedraggled ornithologist doing an impromptu bird ringing demonstration. One couple on holiday in Scotland from Israel were especially thrilled to see a Whinchat be released back into the bracken, and probably left wondering what other mad things Scots get up to in the morning!

But for me, the best thing about this project is its main focus – the woodland migrants whose journeys we are hoping this work will help us to understand better. All of these species are special, and a privilege to work on. Not many people get to spend so much time around breeding Wood Warblers, Whinchats, Tree Pipits and Spotted Flycatchers; even fewer get the chance to see these beautiful birds in the hand. Garden Warblers may be more familiar to many British birders, but this is a species that was, until recently, uncommon in central Scotland. It is still patchily distributed here, and it’s a pleasure for me to spend more time with it. And although Willow Warblers are still among the commonest summer visitors to many parts of Scotland, they have declined alarmingly in most other parts of Britain. We can’t take their continued abundance here for granted. It’s great to know that this project could help us to understand migrant declines and, more importantly, work out what we can do about them.

Mark Wilson, BTO Research Ecologist, reflects on his work tagging songbirds to collect data about their migration routes over the Sahara.

1 July 2022 Songbird migration across the Sahara

I slowly open my hands. The male Tree Pipit I am holding crouches for a moment, before giving a little shake and leaping from my cupped palm, zipping down the wooded slope and landing in a tall birch about 10 m away. He checks out the new colour rings on his leg, which allow him to be identified without being recaptured. A few minutes later, as I am putting away my equipment, I hear him burst briefly into song before he disappears into the trees.

BTO Scotland

11 Jul 2022

Scotland

A Haar Day's Month: Gull Tracking on the Isle of May

WEBSITEEDITOR — Mon, 21 Feb 2022 11:27:57 +0000

Have you ever wondered what it's like to be a seabird ecologist? BTO scientist Daniel Johnston shares his first experience catching and tagging gulls to collect valuable data about their behaviour. Yes

Daniel Johnston

Research Ecologist

Daniel is a Research Ecologist and part of the Wetland & Marine Research Team. His work primarily involves fieldwork and data analysis contributing to seabird tracking and monitoring projects.

Lesser Black-backed Gull

The Isle of May is a National Nature Reserve, and one of the few places the public can walk up to the edge of a seabird colony, buzzing with Guillemots, Razorbills, Puffins, Kittiwakes and large gulls. These raucous breeding grounds are usually incredibly inaccessible. My colleague Gary Clewley and I followed the same routine here for weeks, Gary watching a colony closely from a high vantage point, shouting over the radio to me as I hid behind big rocks in a game of hide-and-seek with the gulls. We were trying to safely capture adult Herring and Lesser Black-backed Gulls on the island, to ring the birds and attach tracking devices.

There is a photo of Gary and myself, smiling, standing on the Isle of May’s concrete jetty next to a pile of boxes and bags. We are waiting for a boat to take us back to Anstruther after a month on the island. The boxes and bags contain every piece of equipment and material imaginable required to catch gulls. Despite all this cleverly designed kit stacked up by us, just about everything else required to capture gulls - particularly clear weather - had been absent for most of the month, and, until a few hours before this photo, we had not been smiling.

Lesser Black-backed Gull with Chicks in the Nest. Edmund Fellowes / BTO

The island is dotted with placards describing the wildlife, flora, and distinctive weather, and it was on one of these placards that I read about a major source of our fieldwork woes, while at the same time standing in the midst of it. Haar. Cold, damp haar. Lighthouses and horns across the Isle were previously used to aid ships in steering clear during times of this dense icy fog, but there was no steering clear for us: we had to wait it out. COVID-19 meant we missed a year of fieldwork, so to actually be on the Isle of May was a thrill. The year off gave us a perspective on the privilege it is to do this work - we might not have been smiling yet, but we were happy to wait a bit longer.

To be able to safely catch the gulls and attach the tracking tag, we needed a few things to align. The birds needed to be well into their incubation period and committed to their nests. This makes them amenable to the not so inconspicuous traps that gull ringers use. Along with the leg loop, there are walk-in traps made of chicken wire placed over the nest; these are simple and pretty obvious, but birds truly committed to incubating their eggs don’t seem bothered by them, and if we placed the traps correctly, the gulls just walked right in.

Alongside timing our efforts with the breeding cycle of the birds, we also needed the weather to cooperate. We didn’t want to disturb the colonies when it was cold or wet during an important period for incubation.

BTO Research Ecologist Gary Clewley ringing a gull. The soft cover over the gull helps to keep it calm. Steve Willis / BTO

When the weather was finally warm and dry, and we had succeeded in actually capturing some gulls, we got down to the real work.

Each gull was deployed with a solar-powered GPS tag to collect information on their movements and behaviour. The tags are attached via a ‘wing harness’, similar to a backpack. The Teflon straps making up the harness are all linked with a loop of cotton. In contrast to the sturdy Teflon, the cotton is chosen for its weakness - it will wear away after 2-3 years, break, and release the straps so the tag falls off. This gives us enough time to collect the valuable data we need, and we don't want to leave the birds carrying a tag for any longer than necessary.

Placing the harness on a gull was the most delicate of our tasks, not made easier by the sometimes (justifiably) bitey gulls. With gulls, the adage is “Once bitten, twice bitten.” To place the tag, Gary and I worked in a team, with one holding the gull (usually me, the trainee) and the other sizing and carefully fitting the harness to the bird. Then we checked and double-checked the fit. We also fitted metal and colour rings to the bird’s legs and then - time to release! This meant placing the bird on the ground, stepping away, and hoping it wouldn’t immediately turn on us. Usually, the gulls just pooped, and flew off. To maintain an illusion of professionalism, I had to resist the urge to salute them as they wheeled around in the sky and returned to their nests.

Tagged Lesser Black-backed Gull. Gary Clewley / BTO

Seabird colonies have a music of their own.

Listen to the Isle of May during the breeding season:

Isle of May Colonies

Audio: Steve Willis

Our efforts, and the gulls' cooperation, will give us information for a range of projects examining gull foraging ecology and the birds’ potential interactions with offshore wind farms. We track their foraging trips from the island during the breeding season, and their migrations during winter. As well as providing an indication of their habitat use year-round, tracking data can also answer more basic questions about the species, such as how high they fly, vital knowledge required for assessing the potential for collisions with wind turbine blades.

Gary Clewley and Daniel Johnston on the Isle of May jetty. Steve Willis / BTO

Examining their movements throughout the year also indicates the extent they may encounter other sources of risk when away from the Isle of May. Of the two species of gull we track from the Isle of May, Lesser Black-backed Gulls undertake the farthest migrations, down to Iberia and Northwest Africa, with some even visiting fishing ports in Western Sahara. As their GPS data are uploaded remotely via the mobile network, you can follow them on the move, and travel vicariously.

We spent a month on the Isle of May, managed to deploy the last of our tags a few hours before our boat arrived, and beam genuine smiles to the camera. Soon after getting back, Gary and I parted to head off to other seabird tracking projects - in June, other species are in the height of their breeding season. But, after two years of waiting, we could enjoy a moment of relief. Kit loaded on the boat, heading to Anstruther, I turned back to the Isle, and resisted the urge to salute.

Acknowledgements – This work was funded by the Department of Business, Energy and Industrial Strategy (BEIS) Offshore Energy Strategic Environmental Assessment programme, and NatureScot. This project was managed by Liz Humphreys. Thanks to NatureScot and Isle of May Reserve wardens. Ringing was undertaken by fully qualified and licensed ringers operating under the British Trust for Ornithology's Ringing Scheme. Deployment of tags was authorised by the scheme’s independent Special Methods Technical Panel.

2 February 2022 Working together for seabirdsDevelopment of a weak-link wing harness for use on large gulls (Laridae): methodology, evaluation and recommendationsFree taster article - tracking Gulls

“Go! Go! Go!”

I yank the cord, heave myself over the rocky embankment and run towards the sea. Herring Gulls rise from their nests as I descend into their colony, aiming for one bird, on one nest in particular. The cord I’ve pulled has triggered a loop to tighten around the sitting bird’s leg. It’s worked: with me beelining towards it, the gull takes off, only to be halted in mid-air. My heart leaps as it floats almost into my reach - but then it kicks off the loop, flaps off into the blue North Sea sky, and my heart falls back down. It’s May on the Isle of May, and we’ve been foiled again.

Seawatching in Haar on the Isle of May. Steve Willis

Wetland and Marine Research Team

21 Feb 2022

Scotland

Citizen Science in Shetland

Anonymous — Tue, 25 Feb 2020 18:24:01 +0000

BTO volunteer Hugh Tooby shares his journey through Shetland as part of the Upland Rovers scheme. Yes

Hugh Tooby Hugh's Twitter

Hugh is tackling some of the biggest gaps in BBS coverage. He has found targets across Scotland and continues in the west, including the Isle of Skye.

Breeding Bird Survey

Monitoring

So, in recognition of this (and an acceptance of the fact that some data are better than none) the Upland Rovers scheme was launched in 2017. Unlike regular BBS squares – which volunteers commit to visiting twice a season between April and the end of June, over a number of years - those surveying Upland Rovers squares can undertake just a single, one-off visit. This has been very successful in increasing upland square coverage since the start of the scheme. However, at the start of 2019 the situation remained that of the 15 squares in Shetland only three had ever received a BBS visit (one not since the 1990s). So, this is where my involvement began.

Esha Ness - the transects cross the grassy plateau. Hugh Tooby

I'm a former GP who retired early, aged 52, to pursue my dream of working in the outdoors. I initially flirted with the idea of becoming a volunteer mountain leader and canoe guide but, as the realities of the paperwork involved these days became apparent, I soon realised I risked turning my outdoor passions into another source of the stress from which I had just escaped. Around this time my son was doing an Ecology Degree. Visiting him on some of the wildlife surveys he was doing opened my eyes to the possibility of getting involved via the citizen science route. After dipping my toe into this new world I realised that there was a shortage of data from the more remote and harder to reach areas of Scotland and I spied an opportunity. I realised I could contribute something useful, whilst also having a lot of fun, by combining my love of exploring remote areas on foot / bike / canoe with volunteer wildlife surveying.

So, when I first heard about the Upland Rovers scheme it seemed like a perfect fit. After visiting three squares in 2017 I really got into it. In 2018 I visited a dozen different areas across the length and breadth of Scotland. For 2019 I wished to continue and spotted the coverage gap in Shetland. In discussion with Ben Darvill (who co-ordinates the Upland Rovers element of the BBS from the BTO’s Scotland office in Stirling) it was agreed that I would visit the islands and attempt to cover all 15 squares.

Balta Sound, Unst. Hugh Tooby

From north to south

I visited the islands for twelve days in the second half of May and enjoyed mostly good weather with just a couple of wetter interludes. My strategy was to start at the northern end of the archipelago and work my way south. Accommodation was mostly camping in my car, with the occasional bed and breakfast when the weather worsened. Sleeping in the back of my car made the early starts required by the survey methodology a lot easier, and meant I got to spend the night in some very dramatic places. In the course of the visit I managed to visit all 15 squares as planned and also fitted in taking part in the annual Orca watch and some general exploration of these fascinating and beautiful islands.

The most northerly islands of Unst and Yell were home to many Arctic Tern. I saw an otter in the early morning calm of Balta Sound, and a nesting Arctic Skua fighting off a Hooded Crow in a spectacular aerial dogfight. I also squeezed in a visit to the amazing headland of Hermaness with its Gannets, Puffins and Great Skuas (affectionately known as Bonxies).

Back on Mainland Shetland, Runafirth gave me my first of many Whimbrel with their haunting seven-note calls and, at Olnesfirth, a pair of summer Whooper Swans. Esha Ness was the scenic highlight and seeing several Red-throated Divers in breeding plumage there on my birthday was a real treat.

At Smirna Dale I recorded 22 different species and the beautiful and remote headland of Braga Ness gave the opportunity of recording Eider in a BBS square. A feature of Shetland is that many of the squares, whilst very definitely upland in character, are next to the sea and only a few metres above it. The Clift Hills in the south of Mainland, however, are very definitely more typical Upland Rovers hill territory. So much so that I was beaten back by low cloud and driving rain on my first visit.

The next day (my last on the islands) was perfect and I was rewarded on my return visit to the Clift Hills with fabulous views and lots of Bonxies; fortunately not in attack mode as their chicks had not yet hatched. A quick dash to the last square at Dales Voe and I had visited all 15 with only a few hours to spare before my return ferry to Aberdeen.

Shetland is a very long way away from the rest of the UK and has its own unique scenery and heritage. It’s also very different in the range and type of birds to be found; plus there’s always the possibility of finding interesting rarities. So, I can definitely recommend a trip there to anyone interested in birds. Gathering some valuable Upland Rovers or BBS data whilst there has the potential to add real value to the visit.

If you participate in the Breeding Bird Survey, we'd love to hear what makes your square(s) special. If you've thought about BBS but haven't taken the plunge, what's holding you back? Let us know in the comments below.

Take on an Upland Rovers square

If you are an experienced bird watcher with a love for the uplands, then taking part in the BBS Upland Rovers scheme might be for you.

Find out more

BTO volunteer Hugh Tooby shares his journey through Shetland as part of the Upland Rovers scheme

2 February 2020 Breeding Bird SurveyThe Breeding Bird Survey Report

Since 1994 the BTO/JNCC/RSPB annual Breeding Bird Survey (BBS) has gathered essential data about the UK’s bird populations. However, many of the scheme’s randomly selected 1 km squares in remote upland habitats have received less coverage because of the access challenges they present. This is a problem as the UK’s vast uplands support important populations of breeding waders, raptors and songbirds. A better understanding of population change among these species would be valuable for conservation management, land use and climate change mitigations.

Clift Hills, South Mainland, Shetland. Hugh Tooby

25 Feb 2020

Scotland

Tracking Short-eared Owls: Notes from the field

WILLIAMSKELLORN — Tue, 28 Jan 2020 11:16:20 +0000

Why would anyone choose to spend a winter’s night out on a cold Orkney moor? Ben Darvill gives an insight into the dedication of Short-eared Owl fieldworkers, and their amazing discoveries. No

Ben Darvill

Head of Development and Engagement

Ben is responsible for developing and supporting BTO volunteer efforts in Scotland.

Birdwatching doesn’t often send your pulse sky high, but it turns out that trying to find a Short-eared Owl nest does.

To fit a tag you need to catch an adult, and to do that you need to find the nest. So on a fine May evening in 2017 I found myself crouched amongst the heather, looking out over an expanse of moorland, hoping. I’d seen adult owls in the area and I had my suspicions, but I wasn’t sure. I forget how long I waited - an hour perhaps, maybe two. Then an owl appeared, carrying a vole… Birdwatching doesn’t often send your pulse sky high, but it turns out that trying to find a Short-eared Owl nest does.

An adult carrying food is a good sign - it suggests that there’s a nest nearby. It perched briefly on a tussock, then flew a short distance and dropped out of sight. A few seconds later it was up and off, without the vole. I stared, hard, trying to find something distinctive amongst the sea of cotton grass, rush and heather. With my eyes fixed on a nondescript tuft, I set off across 500 metres of heathland, trying not to blink. Walking across uneven ground without looking down isn’t easy, so I stumbled and lurched my way towards the tuft, desperately trying not to lose sight of it.

A tag weighs just 11 grams – less than a two pound coin.

“Don’t make eye contact,” John had said (John Calladine, BTO Scotland’s Senior Ecologist and Short-eared Owl project lead). How do you look at an owl without making eye-contact? As I approached the tuft my pulse raised further still. Then, there they were: the piercing yellow eyes of the female on the nest, staring right at me! I tried not to look, marked the location on my GPS, and beat a hasty retreat. Little did I know how significant that owl, which we caught, tagged and released a few days later, would turn out to be.

Female who reared two broods in two countries in the same year.

Extraordinary movements

The technology in these tags is incredible. They weigh just 11 grams – less than a two pound coin – yet house a solar panel, battery, GPS receiver, satellite transmitter and a miniature computer. The chip is programmed to record a fix every three hours (light levels permitting), and to relay this information to John via the satellite network. The precise GPS fixes have given us fine-scale detail on habitat use – information which is already forming the basis of land management recommendations which we hope will help conservation efforts.

It’s the longer-distance movements which have really grabbed the headlines, however, and of the five birds tagged in 2017, ‘mine’ turned out to be the star. She overwintered locally, then wandered around Scotland in March 2018 – perhaps looking for higher vole densities, or a better mate? By late-March she had settled down to breed, back in Perthshire. Then, not long after her chicks had hatched, things took an unexpected turn. She abandoned her territory, leaving the male to rear the chicks, then flew to Norway and bred again! Two broods in two countries in the same year, with different mates – quite extraordinary.

Her unexpected wanderings didn’t stop there, however. In the months that followed we tracked her movements to Ireland, Devon and Norfolk, and recorded her final hours as she attempted to migrate back to Norway in spring 2019, sadly perishing in a storm close to the Norwegian coast.

Arran to Morocco.

At the time of writing, 10 birds have been tagged in Scotland, each with a unique story to tell. Another female, tagged on Arran in June 2019, ranged over SW Scotland before flying south to Devon. After a couple of days here she continued on, using a strong tail wind to travel 495 km into France in just six hours (averaging 82.5 km/h!). She crossed the Pyrenees on 13 November and the Strait of Gibraltar on 24 November, settling in Morocco. Her tag is currently dormant, but is due to reactivate in early February – we can’t wait to find out where she is now!

Short-eared owls don’t seem to live very long (the longevity record for a ringed bird is around 6.5 years) so it’s no surprise that some of our birds haven’t survived. Information about where and when they die can be useful, of course. A different Arran female provides one such example. She remained on the island until October, then headed south, transmitting from Ireland, Wales and the south of England on her way to Brittany. Sadly her movements then stopped abruptly on the verge of the A28 motorway, strongly suggesting that she was killed by a vehicle. We’re used to seeing Kestrels hovering over motorway verges (though less commonly in recent years) and I wonder whether she was hunting when she died.

Tagged Short-eared Owl. Anne Carrington-Cotton

A new milestone

Thanks to extraordinary dedication and perseverance, John and co-worker Neil Morrison recently achieved a significant project milestone. In December of last year, when most of us were enjoying mulled wine and mince pies, John, Neil and local collaborators were out on a cold Orkney moor in the middle of the night. Fine-mesh ‘mist nets’ were erected and an array of loudspeakers played owl calls and vole squeaks. Their efforts were rewarded with the sum total of nothing at all – not one single owl. But in January 2020 they tried again, this time on Arran. There were four different teams out this time, and they were in luck, catching a single male Short-eared Owl. This was the first time that they’d managed to catch and tag an owl outside the breeding season.

What next?

The job isn’t over yet. John aims to tag up to 25 Short-eared Owls from sites across their breeding range in the UK. By following individuals from a range of locations he hopes to better understand how variation in local conditions affects their breeding success. It’s possible that local habitat composition, food availability or predator density could be affecting the owls’ reproductive output, for example.

Known unknowns?

Reflecting on what the project has achieved to date, is it fair to say that we now know where ‘our’ breeding Short-eared Owls mysteriously appear from? Not really, no! Birds that we’ve tracked have wintered in Scotland, southern England, Ireland and Morocco. They seem to be real nomads, exploiting resources that are patchy in both space and time. That’s part of what makes the project exciting though - we really don’t know what’s going to happen next. Follow @BTO_Scotland on Twitter or keep an eye on the project webpage for future updates.

Help fund Short-eared Owl Tracking

As well as the expertise and commitment of John and his team, this project needs financial support. Each tag costs £2,000 and the annual data costs are £1,000. You can help donating to our Short-eared Owl Tracking Appeal. Your support will help this pioneering project to continue.

Find out more

Acknowledgements

We thank the individuals without whose local knowledge of ‘their’ Short-eared Owls, this work would not have been possible. We are also indebted to the charitable trusts and small group of individuals for their generous donations which have allowed us to make ground-breaking progress on this challenging project. We are especially grateful to Neil Morrison who was key to starting this work in Perthshire, has been in on the tagging of all birds so far, and continues to be key to its progress.

What do you think about modern tracking technology and its use in our research? What gaps in our knowledge do you hope we will one day be able to address? Let us know with a comment below.

Why would anyone choose to spend a winter’s night out on a cold Orkney moor? Ben Darvill gives an insight into the dedication of Short-eared Owl fieldworkers, and their amazing discoveries.

2 January 2020 Short-eared Owl tracking AppealScottish owl tracked to MoroccoBird tracking

I’ve been monitoring the birds of prey in a patch near BTO Scotland’s Stirling headquarters since 2015. This mostly involves keeping an eye on the Buzzards, Kestrels, Sparrowhawks and Ravens, then sending information to the Scottish Raptor Monitoring Scheme. In some years, however, Short-eared Owls appear, seemingly from nowhere. They seem to be declining, and we need to know more about their movements to inform conservation efforts. Could state-of-the-art satellite tags help to shed some light?

Short-eared Owl tagging. Chris Wernham

BTO Scotland

Short-eared Owl tracking Appeal 28 Jan 2020

Scotland