Great rides: Breaking birding records by bike

‘Big days’ have long been an established part of the birding calendar. During a big day, small teams of birders record as many species as they can find in a defined area over a 24-hour period. In the UK, such events are often conducted within a county or bird-club recording area.

Some birders undertake a big day on 1 January to get their new year list off to a strong start. Most emphasis, however, is placed on choosing a spring date, when migration is in full flow and a range of summer and winter visitors are possible, affording the greatest range of species to target.

In my home county of Oxfordshire, the big day record stood at 114 species for many years until 2021, when a team surpassed this with 117. The biggest day totals have been set by teams in cars, often driving large distances between sites to maximise the number of species available. The record in neighbouring Berkshire, set in 2006, stands at 121 species, but involved driving more than 500km in a day!

In recent years, increasing awareness of human-driven climate change and a desire to reduce personal carbon emissions have made some in the Oxfordshire birding community wonder about the feasibility of a low-carbon big day by bike.

In early 2023, I was contacted by Ben Sheldon and Thomas Miller, who asked if I would be interested in doing a green big day in Oxfordshire. My first reaction was one of incredulity. Big days are exhausting, involve a very early start and a late finish, and typically cover great distances on foot – add in a hefty amount of cycling and this becomes a really tough physical challenge.

I couldn’t make it, but Ben and Thomas covered 150km by bike and managed 113 species –only just short of the all-time car-based record. There was a sense of shock in the local birding community that such a total could be reached without using a car.

It raised the question of whether bikes could be used to set a new Oxfordshire big day record. There was only one way to find out. We arranged a bike-powered big day for spring 2024.

The weather dilemma

Weather is the single biggest factor that can impact a big day’s success but is also the one factor that cannot be controlled. Past Oxfordshire big days had been ruined by high pressure, blue skies and sunshine – lovely conditions to be out and about, but far from the low cloud and rain showers needed to ground migrating birds and produce a larger species total.

Historically, early May was regarded as the optimum time for a high big day total. However, Ben analysed local bird records and concluded that late April may prove even better. Most summer migrants would be back in numbers by late April, with only Spotted Flycatcher unlikely. There was also a greater chance of encountering lingering winter visitors.

Ben’s hunch was that late April was often best for inland passage, especially for waders, Little Gulls and Arctic Terns. It might also be better for passerines such as Northern Wheatear, Common Redstart or Whinchat, although these are becoming harder to predict. Furthermore, late April negated the effect of increased public disturbance at some sites over the bank holiday weekend.

The success of that first bike-powered big day in 2023 proved that late April could produce a competitive species total. Weather in the last week of April 2024 was dynamic and changed radically from day to day.

The team committed to Saturday 27 April, despite a late shift in the forecast, which suddenly predicted heavy rain both early and late in the day. Good weather for finding migrants, perhaps, but not good weather for cycling.

The topography of Oxfordshire makes it an ideal county to attempt a big day by bike. Most of the key birding sites are within a relatively small area, around Oxford and the Thames Valley. Gravel pits are within easy reach, as are Farmoor Reservoir, Port Meadow and the key site of Otmoor RSPB. We agreed on a route of 190km but had the option of reducing this by 40km if we were doing well for waterbirds.

At 4.30am on 27 April, I was waiting on my bike in the darkness of Oxford’s High Street. The wind was in the north-east and I could smell the petrichor sweeping in with the rain. There were no two ways about it: we were going to get wet.

Approaching lights signalled the arrival of Ben and Thomas, and with that our big day began. We pushed off towards our first stop on the Chiltern escarpment, some 28km away. All three of us were soaked through well before we started the strenuous climb up Watlington Hill.

Teamwork is key

Tradition in Oxfordshire dictates that big days should be completed by a team of at least three people. Only birds seen or heard by all members of the team count towards the total. This entails a degree of trust between the team members. We used eBird to record the bird species that we saw and heard, setting up a trip report for the day, so that we could check the running species total from the field.

On any big day, there will be birds that are not seen well by all team members. Unfortunately for us, this occurred before daylight had even broken. Watlington Hill is a well-known climb among local cyclists. The first section is quite steep and favours the stronger, lighter riders. Everyone climbs it at their own pace. Thomas led the way, being a strong cyclist and a good climber.

I was next, followed by Ben, laden with a rucksack containing a small scope. Thomas and I waited at the top and Ben cycled towards us, but with some horrifying news. Halfway up, a Long-eared Owl had flown across the road in front of him.

Climbing Watlington in the pitch dark and freezing rain was painful enough. To miss what could be the bird of the day, and so early in our attempt, was excruciating. As all three of us hadn’t seen the owl, we couldn’t count it in our team total.

Seriously chilled

Cycling and birding require very different clothing. Cycling clothing is designed to fit tightly, to reduce drag and to allow heat to dissipate. Most cyclists are hardened to getting wet, but cycling usually generates enough warmth to prevent serious chilling. One challenge of bike-birding is that at some point you must stop cycling and go birding. That is when the risk of chilling occurs.

Things went from bad to worse after failing on a scarce breeder along the Chiltern escarpment. The cold north-easterly wind was strong, chilling our wet bodies to the bone. We cycled to Cowlease Wood to target woodland species at dawn, but by the time we arrived, Thomas was becoming hypothermic. He was shaking like a leaf and was unable to use his hands to change from cycling to walking shoes.

Ben had an emergency down jacket in his backpack and gave it to Thomas to try to raise his body temperature. Fortunately, the rain abated and the extra layers of clothing prevented hypothermia from setting in.

There was a good selection of singing woodland birds, including numerous Firecrests, as well as Mistle Thrush and Eurasian Nuthatch – two species that often prove tricky on spring big days. Better still were fly-over Eurasian Siskin and singing Lesser Redpoll – we hadn’t anticipated seeing either and they were an important morale boost after the toughest of starts to the day.

Ups and downs

After birding the Chiltern woodlands, we cycled 45 minutes south-west towards the Oxfordshire Downs, finishing in a short but steep climb. The rain came and went, but roadside species such as Raven and Woodlark kept the total ticking along. While the country lanes were traffic free at that time of the day, the road surfaces on minor roads were often very poor. I hit a flooded pothole and punctured my front tyre, requiring a quick change of innertube.

The downs were productive, with Corn Bunting, European Stonechat and Meadow Pipit, plus a fly-over Common Cuckoo and bonuses of Northern Wheatear and Tree Pipit. The last two species were the first hints that our gamble to risk poor weather for the big day was paying off.

However, the temperature was only just above freezing in the wind, which kept two targets, Eurasian Stone-curlew and Grey Partridge, hunkered down and out of sight. It’s important to remember that all species count equally on a big day and we reluctantly moved on.

Heading north, a 45-minute ride took us to Appleford GP, where the cloud forced down hirundines and Common Swifts to feed low over the water. The change in habitat brought a rush of waterbirds, including Little Grebe and Grey Wagtail – both species that have troubled big day teams in the past.

By midday, scanning of a flooded field between Didcot and Abingdon produced big-day gold: waders! A Green Sandpiper, three Little Ringed Plovers and a Ringed Plover were expertly picked out by Thomas and Ben.

The second-longest ride of the day followed: a 20km effort over Cumnor Hill to Farmoor Reservoir. News had already reached us that three adult Little Gulls and an Arctic Tern were present, feeding over the reservoir.

Importantly, Farmoor also provided much-needed food, hot coffee and the opportunity to discuss our strategy for the rest of the day. We realised that if we could reach the 100-species mark before arriving at Otmoor then we had a good chance of getting near the 2021 record total.

Otmoor’s reedbeds would provide many specialist species, and some night singers too, although the forecast of heavy rain from 7 pm was a concern. Picking up Common Sandpiper, Common Kingfisher and Sedge and Garden Warblers brought us to 93 species by 3 pm.

At Wytham, Marsh Tit, Green Woodpecker (at last!) and Little Egret took us to 96. Adam Hartley was kindly waiting for us at Port Meadow – in an efficient stop, Great Egret, Dunlin and Common Shelduck were added. While en route through Oxford, Ring-necked Parakeet became species 100. The record attempt was on.

Onwards to Otmoor

The 12km ride to Otmoor RSPB meant that we had covered some 130km by the time we arrived. Any signs of fatigue were outweighed by another burst of new species: Common Redshank, Eurasian Curlew, Black-tailed Godwit and two Grey Plovers were all noted, with Northern Pintail and Common Crane also added.

A Barn Owl in a nearby hedgerow was species 108, before we cycled onto the main bridleway through the reserve. A Peregrine Falcon was met with cheers as it circled overhead; Ben picked out a calling Eurasian Bullfinch and we saw the long-staying Barnacle Goose.

The screens at Otmoor provided the only Common Pochard of the day and then some reedbed specialists: Western Marsh Harrier, Eurasian Bittern and, eventually, a calling Water Rail. The light began to fade and the predicted rain started to fall, but at least three Grasshopper Warblers began singing in the wet gloom (116). The record was within touching distance.

Although we’d seen a remarkable 12 wader species in the day, we hadn’t had Common Snipe. Walking back onto the reserve, persistence eventually paid off with a distant singing snipe, followed by a closer drumming bird (117).

The finale – the end-of-day magical moment – came in near-darkness a few moments later when Thomas shouted: “Short-eared Owl!” Species 118 was on the list and we’d set a new Oxfordshire big day record, with everything seen by bike and on foot. In total, we’d covered 150km by bike and a further 16km on foot.

On reflection

It is one of those inevitable quirks of time-restrained birding schedules that no big day team sees all the species recorded in a single day. In 2024, we missed Eurasian Sparrowhawk, Eurasian Hobby, Western Cattle Egret, Red-crested Pochard, Eurasian Stone-curlew, Grey Partridge, Common Redstart and Whinchat.

Two further species were not included in the team total as they were not seen by everyone (Ben’s predawn Long-eared Owl and a Tawny Owl heard on the ride home), but it did mean that 120 species were recorded without using a car in Oxfordshire on 27 April 2024. For context, birders in neighbouring Buckinghamshire took part in a multi-observer effort across the county on the same day, using motorised vehicles, and saw a total of 124 species.

And what of attempting a big day by bike? Clearly, over longer distances, it is much quicker to drive than to cycle, but over shorter distances, and especially in urban areas, the difference is often rather less than anticipated, depending on cycling speed.

In our experience, a big day by bike loses very little in terms of species recorded when compared to cars. It helps that Oxfordshire is a medium-sized county that is relatively flat, with good birding sites close to each other.

In larger counties or areas where hotspots are more widely spread, a car is more advantageous. The final total will also depend on location: in 2011, Nick Moran and Chris Mills saw 144 species in a day in Norfolk even though they covered ‘only’ 80km by bike.

In addition to the obvious cut in carbon emissions, another potential advantage of using a bike is that more birds can be recorded while travelling, with the open-air setting meaning birds could be heard or seen while in transit – something not possible in a car. In 2023, Ben and Thomas scored their only Yellow Wagtail and Jay in this manner.

Undertaking a big day by bike will only suit those already conditioned to cycling. It requires a degree of physical fitness and will not appeal to – or be possible for – everyone. But it doesn’t have to involve travelling huge distances across a county – spending a full day exploring a local patch or small area will be every bit as rewarding and may well turn up unexpected species.

For those birders who already cycle, a green big day is a fantastic way to explore their home county, to see a wide range of habitats and birds in a single day, to get physically fit and finish with a real sense of achievement. In setting a new county big day record without using a car, the 2024 Oxfordshire team has shown the enormous potential of this low-carbon challenge.

This was first published in Birdwatch 386 (August 2024) and is republished here with kind permission of the editor. The magazine is available in newsagents, and you can find out more at BirdGuides, where you’ll also find image galleries of all the birds mentioned here.