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
asa logo



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


Win win situation for the Hedgehog and for the Frogs in New Zealand

Phil Bishop and frogGuest post by Phil Bishop
acting director at The Centre for Science Communication (University of Otago)
Associate Professor/Chief Scientist ASA


Hedgehogs are cute and cuddly.

Many children are exposed to characters like Beatrix Potter’s Mrs Tiggy-Winkle, so it was no surprise that when I found a baby hedgehog (called a hoglet) sitting motionless on the sidewalk at 4.30 in the afternoon that I felt moved to help.

This is in New Zealand and many people may not realize that New Zealand was probably one of the last places in the World to be colonized by land mammals.  The only native mammals we have in New Zealand are two species of bats and marine mammals like seals and dolphins.  So all the rats, mice, stoats, weasels, possums and of course, hedgehogs, have all been introduced in the last couple of hundred years.

Hedgehog named Pepper in new zealand

Nearly all the land mammals are introduced species and the native wildlife (birds, reptiles and frogs), who have been happily evolving on their own for the last 80 million years in the absence of mammals, haven’t a clue what to do when they encounter an introduced, vicious, mammalian predator.

I ended up in a dilemma – should I nudge the hedgehog into the oncoming traffic, it was cold and going to die anyway, or should I nurse it back to health and when its old enough, release it back into the wild to wreak havoc with our native wildlife or get squashed on the road as an adult!

The decision was a ‘no brainer’, I couldn’t let this little fellow die a horrible death so I had to rear the little 100 gm orphan.  So now we have a large female hedgehog – a couple of pounds in weight – a vicious predators of my favorite animals that I have been working so hard to save – frogs!  What to do?

Luckily I managed to find someone who was looking for a hedgehog as a pet – so she is now living with a family, never to be released to the wild, never to produce more hedgehogs, never to run the gauntlet of crossing a road but always having her every day needs taken care of.

A win win situation for the hedgehog and for the frogs!

While they might seem cute and cuddly hedgehogs are significant predators of frogs, lizards and even ground nesting birds – and probably play a significant role in the decline of Leiopelma frogs in New Zealand.

frog and hedgehog by Phil Bishop