Osmotherley Toad Patrol

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Steve Rogers - Coordinator for Osmotherley Toad Patrol


Osmotherley Toad Patrol has been operating since 2002 along a 2 km stretch of minor road to the west of Cod Beck Reservoir, about a 1.5 km to the north of the village. The aim of a toad patrol is to reduce the amphibians casualties as they try to cross a road during their spring breeding migration. In addition to Common Toads, Common Frogs and Newts (in our case Palmate) are also encountered. Numbers of amphibians are forwarded at the end of the season to the charity Froglife who have a “Toads on Roads” project to collate data from across the UK. This enables Froglife to research population trends.

Cod Beck Reservoir - Toad Breeding Site (Steve Rogers)
Cod Beck Reservoir - Toad Breeding Site (Steve Rogers)

Toad patrolling is quite simple. Volunteers, wearing weatherproof clothing and Hi-Vis gilets, walk the road from dusk for a couple of hours using high power torches to rescue the amphibians in a bucket and then release them safely. There are two main difficulties with the patrols.

First, are the weather conditions suitable? Toads, being “cold-blooded”, will not usually move if the air temperature is below about 8oC (though they may move at lower temperatures if it has been warm during daylight followed by a sudden cooling). Frogs (and newts) will move at lower temperatures with perhaps a threshold as low as 4oC. Damp weather also promotes migration. Consequently, a combination of, say, 10oC and moderate to heavy rain will result in a very busy night for the patrol with up to 1,000 toads being collected in a few hours. We therefore rely a lot on the weather forecast (Met Office forecast for Osmotherley Youth Hostel) to alert volunteers that a patrol is needed.

Secondly, after toads have moved from the moorland to the reservoir and breed they then exit in the opposite direction to return to their feeding habitat. Toad migration can last several weeks, probably because the animals are spread over a large area of moorland and may take several days to reach the road. So there is a period lasting week or more when the problem for patrol volunteers is to decide which direction a toad is wishing to go! It is believed that Common Toads do not feed between emerging from hibernation and breeding. They are therefore usually “marching” with some purpose toward the moor which helps the volunteer’s judgement.

Data from Osmotherley Toad Patrol

The results from the 17 years of toad patrols at Cod Beck are summarised in the Table 1. Informal patrols were carried out by local residents for several years preceding 2002. A newspaper article in 2001 publicised the setting up of an organised toad patrol for the following year and resulted in good numbers of volunteers. I had previously taken part in similar patrols in Cheshire over a number of years and was able to advise and train patrollers. The result was that we helped high numbers of animals for a few years; Osmotherley was probably in the top three sites nationwide. Even the advent of a large moorland fire in 2004 did not greatly suppress toad numbers, though we did find some injured animals.

Table 1: Summary of Osmotherley Toad Patrol Results for the years 2000 to 2019 Figure 1		The difference in splat density recorded on vehicle journeys between a) 2004 (in South East England) and b) 2019 (in Kent). Between 2004 and 2019 there was a statistically significant difference in ‘splat density’ of the order of approximately 50%, from an average of 0.2 splats per mile to 0.1 splats per mile, in 2004 (n=3838) and in 2019 (n=667).
Table 1: Summary of Osmotherley Toad Patrol Results for the years 2000 to 2019 (n=667). Full size images can be seen by clicking on the graphics
A bucket full of toads (Steve Rogers)
A bucket full of toads (Steve Rogers)

Unfortunately, after this initial success the number of volunteer patrollers declined with a concomitant decrease in toad numbers rescued. Numbers of frogs also dropped dramatically. This may have been caused by disease ("red leg" (Bacillus hydrophilus fuscus) and Chytrid fungus (Batrachochytrium)). There was an unfortunate occurrence in 2009 when a search party was called out to look for missing chef, Claudia Lawrence, and the vehicles  involved killed hundreds of toads and made patrolling impossible on the busiest night for migration. At Cod Beck we see only the smallest of UK newts i.e. Palmate Newt which are difficult to spot on the road.

In 2011, the reservoir (owned by Yorkshire Water) was drained for repairs to a very low level and this seems to have been the most serious cause of decline in toad numbers recorded. From 2013 onwards we have had a series of very cold, and often dry, early springs which have resulted in migration being delayed until late March or early April. This coincides with the beginning of British Summer Time when the evenings become much longer and patrols consequently shorter in duration (usually finishing around 10 pm). Migration may continue through the night if weather is suitable but volunteers need to sleep!

We can also examine how toad numbers build up over each season in Figure 1. This demonstrates the great variation in the pattern of migration. In particular, it shows how an early start to the migration usually increases the total numbers of toads collected. In some years (e.g. 2008) migration started early but then stalled for days or weeks at a time because of a change to cold weather. In 2013, toad movement did not start until 13th April as a result of an exceptionally cold spring. On the graph I have also indicated (by an open yellow circle) the day at which we noticed the first egress from the breeding site.

Figure 1: Cumulative Toad Numbers for the years 2002 to 2019
Figure 1: Cumulative Toad Numbers for the years 2002 to 2019. Full size images can be seen by clicking on the graphics

Are You Interested in Helping?

We would be delighted to have some new patrollers. Most people that come to help thoroughly enjoy the experience. It would be preferable that volunteers come from within a reasonable travelling distance because we cannot predict accurately, until maybe the day before or even on the day, whether it will be worth turning out in the evening. I'd hate to drag someone from 50 miles away to find no toads appear. Even if there are no toads it is usually an enjoyable way to spend an hour or so as there is often other wildlife to be seen or the night sky to look at as well as having a chat with like-minded people.

If you are interested please email Steve Rogers at There is a lot more information about Froglife’s “Toads on Roads” project here - and a link to find other toad patrols.

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