Frogs Crossing the Road in the Rain

Rio Grande Leopard Frog by Sara Viernum

Rio Grande Leopard Frog by Sara Viernum

A frog fan, Brian, emailed about the frogs in his area crossing the road when it rains, and I asked a few experts to advise him. We all agreed to share this content so you can know what to do in your own area.

Brian asks:
To reiterate our conversation, there is an ecosystem in and around the Salt Pond community in Bethany Beach DE, which subsequently is intertwined by a few roads. There is one particular stretch of about two blocks where, like clockwork, when it rains the frogs cover the street. It seems to be two species doing this; the bull frogs and little peepers. I did a rough estimation of about 125 of these frogs are being killed by car traffic every time it rains. That’s roughly 4000 per summer season. What is it about the rain that draws these frogs to the pavement?  And what practical solution can be done to lessen the slaughter?

Best regard, Brian H.

Bullfrog by Sara Viernum

Bullfrog by Sara Viernum

Two responses from the experts:

Hi Susan and Brian,
Happy for others to chirp in as well, but the frogs are not so much attracted to the pavement, but the rains signaling the fact that its time to breed!  So when this happens the frogs migrate from where they live their everyday lives to a suitable breeding site, which hopefully still exists.  I’ve seen cases where the traditional ponds have been turned into carparks or shopping malls and all the frogs turn up and say “WTF?” And inevitably die.  There is another explanation and that depends upon the size of the frogs – if they are adults then the above explanation is probably true, however if they are metamorps or juveniles then its quite likely this is a mass migration AWAY from the breeding site of newly developed froglets to find a good place to live and the only way they can avoid drying out on the hostile pavements is to travel when it rains.

OK – what can be done to save them?

People try many things, during rainy days you can get volunteers to help the frogs across the roads, you can put signs up to warn motorists and tell them to be careful, you can close the roads – all these have differing successes depending on manpower, but the best solution is to advocate for some frogs tunnels and drift fences to be installed.  Essentially you erect a barrier, which for these species would need to be carefully constructed as peepers can climb very well and bullfrogs can jump very well, and these barriers prevent the frogs from crossing the road and direct them to an underpass where they can cross the road safely (obviously the same needs to happen on the other side so that they don’t get squashed coming back).  Having said all this, both the species mentioned are fairly common species and are not under threat (although it would be good to get their ID professionally confirmed) and are not in decline – at the moment, so it would be difficult to motivate city councils or governments to take action for a fairly common species.  But its great that Brian wants to do something an it would be great if Kerry Kriger (Save the Frogs) or I can help.

All the best

Phil Bishop
Associate Professor
Chief Scientist
Amphibian Survival Alliance
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Ranid Eggs by Sara Viernum

Ranid Eggs by Sara Viernum


Susan with Frogs Are Green forwarded your e-mail to me.  Roadways are a huge problem for herpetofauna as you’ve found out.  The frogs are mostly likely coming out on the roads during rainy nights to move to breeding grounds or in search of food.  Frogs love rainy nights and move around a lot during them.  Some possible solutions to help save the frogs are to petition the city and or your local Fish and Wildlife/Dept of Natural Resources office to install frog crossing signs and get the speed limit lowered and/or to install fencing that diverts the frogs to an under road crossing (if one is nearby).  If this is a little used road you might asked that it be closed during certain seasons like the famous snake road in the Pine Hills in Southern Illinois that is closed twice a year to allow rattlesnakes to migrate.  Another possibility is to start a citizen group that devotes time to cruising the roads on rainy nights saving the frogs.  I’ve heard of a few areas in the US where people do this.

Thanks for being concerned about the frogs.


Sara Viernum, The Wandering Herpetologist

Spring Peepers by Sara Viernum

Spring Peepers by Sara Viernum

8 thoughts on “Frogs Crossing the Road in the Rain

  1. We went to the store near our cabin after a rain storm. There were hundreds if not thousands of frogs crossing the roads! I swerved the best I could to avoid squishing them! All sizes too!
    Freaked us out completely

  2. Hi Sher,
    Yes, this a dangerous situation for frogs. You should alert your county wildlife or nature conservancy and they may be able to help these frogs safely cross. They may also post the “frog crossing’ signs which may help. Where are you located and do you recognize what type of frogs they were?
    Thanks, Susan

  3. So, I am out now and going for a walk after a big rain storm last night. It is currently sprinkling outside. My walk must have been 4 miles. I noticed while walking , dead frogs. Clearly ran over but why so many and why in the road? As I am nearing home, I see a frog on the side of the road , not hit but laying still. I tapped it and his leg moved. I picked him up and placed down in some grass. I then googled and found this article. These poor thing! He wasn’t very responsive so , I hope the rain wasn’t damaging. It was coming down pretty hard at times. Well , I hope the frog will be ok and I will be on the lookout

  4. Hi Christine,
    Yes, unfortunately when we build homes and roads where there used to be woods and ponds, the frogs don’t survive as they could have. In many places they post signs for drivers to drive slowly because it is a frog crossing. Can you share what city, state or country you are located?
    Thanks, Susan

  5. Hi I am vishal from India. …..I observed that the many frogs are dieing on the during rainy season. ……then l search why does these occur. ….then I found your article. …I am reading it but I can’t cleared these concept. … question is that……in frogs eyes or skin. .is there any sensation ….which attracts the frog to the headlight of car or bike. ….and which causes death of frog. ….? …..please reply by email. to me …

  6. Thank you for your article and website. For the past month after a rain- myself and a neighbor have been saving frogs in my neighborhood. Sadly, we still find many hit by cars. The worst is baby frogs and other frogs who jump out of the pond, jump down a man made curb then get stuck unable to jump the curb to return to a pond. Do you have any suggestions other than the ones mentioned here? I’m also wondering why I have not seen this issue any other years in the same neighborhood? Thank you.

  7. Hi Kristin, Can you share your location? Also, it’s wonderful that you helping save these frogs! I’m a bit confused. In which direction are the frogs going? Away from the pond or toward the pond? Are they staying close to the pond but exploring? Please share more details and a photo if you can! – Thanks, Susan

  8. Hello Vishal, I will need to check into this. I’m not sure if they are drawn into car headlights. Will ask around.
    – Susan

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