Thursday, April 7, 2016

How To Find An Amphibian Road Crossing

Every spring in the northeast, as the snows melt and the ground begins to thaw, amphibians move out of their upland overwintering habitat down into wetlands to breed and lay their eggs. For most of these early spring breeders, the best breeding habitats are vernal pools and semi-permanent ponds that dry up in the summer, but permanent ponds, wetlands, and beaver swamps are good places too. The spring breeding amphibians need to emerge from their overwintering sites, migrate to the wetlands, mate, lay their eggs,  and then move back upland into the woods to forage (though some will hang out in the wetlands to forage and head to overwintering sites in the Fall).

Spotted Salamander laying eggs in a semi-permanent pool.
Later in the season, after eggs hatch and the young metamorphose, juvenile amphibians move out of the wetlands to join the adults in their summer and winter habitats. Unfortunately, roads often cut right between breeding and summer habitat so adult amphibians need to cross those roads twice every year.  If a road has enough traffic, very large proportions of the amphibians are crushed and on busy nights, just a single vehicle can kill dozens, or even hundreds of amphibians.

Blue-spotted Salamander crossing a road in Salisbury, VT
In Monkton, Vermont, an underpass was created to funnel amphibians safely under one busy road, and there is an ongoing effort to monitor amphibian numbers at other sites. The public is welcome to attend one of the hosted road crossing events (email Warren King to get on the mailing list), which are located in low-traffic spots with LOTS of amphibians. The hosted road crossing events are great opportunities for people of any age or experience to see a lot of amphibians and are a great way to expose young kids to nature in a very safe environment.

A future herpetologist proudly showing off a Spotted Salamander.

We don't know where all the good crossing sites are, though, and rely on reports from citizen scientists to help identify where those spots might be. While you are more than welcome to attend a hosted amphibian migration at one of the regularly-monitored sites, it would be great if you try to find a new spot and report what you find. VTrans even released a video asking for help finding migration spots, and the VT herp atlas has a form for reporting road crossing sites. In this post I'll show you how to find migration crossings all on your own.

Finding a new amphibian road crossing is pretty simple if you know what to look for. Because most of these early spring breeders overwinter in woods and breed in wetlands, such as Blue-spotted Salamanders and Wood Frogs, all you have to do is open a road atlas or browse Google Maps and look for a place where a road passes directly between woods and water. I like using USGS topographic maps or gazetteer road maps because they show marshes that might not be visible on Google Maps, but most people are going to use Google Maps, or something like it. That's fine. If you want, though, a good website that allows you to easily browse topographic maps is 

Below is an example of the sort of places to look for on a topographic map. I have never been to this site but based on its location in southern New Hampshire, would guess that it might have Wood Frogs, Spring Peepers, Blue-spotted, Spotted, and Four-toed Salamanders all crossing in the early spring.

Both sites marked on this map lay between wetland habitat and a wooded hill. I found this site using, but the same symbology is used by Gazetteer road atlases, which are traditionally stored under or behind the passenger seat.

Looking at the zoomed in areal imagery of the more western site you can see that there appears to be a wetland, possibly a beaver meadow, below the road. 

The same is true of the more eastern site marked on the first map.
For species that overwinter in rivers and lakes and breed in floodplains, such Northern Leopard Frogs, or species that live in the water and forage on land during rain (Green Frogs and Bullfrogs), you would want to look for a place where a road lies between a river or lake and flat valley fields or wetlands. Roads that bisect wetlands and flood planes are good too. Aside from some Leopard Frogs, these sites usually don't have much action in the early spring, but are pretty active in the summer.
This is a good example of a site where a road bisects a river and flood plane.
A Green Frog chowing down a nightcrawler on the road in the above map.
Ok. You've found some spots to check out. Then what? Wait to go out until a rainy night when the snow has melted off of at least 50% of the ground and air temperatures are in the high 40's or low 50's Farenheight. Usually in Vermont that's late March, but migration activity continues through the spring and into early summer for some species. Sometimes you can even find salamanders moving over snow to get to a wetland.

After the ground thawed, some fresh snow did not deter this salamander from migrating to a breeding site. Several dozen others were found that night.

In mid-summer you can find lots of amphibians out foraging, just go out whenever it's raining. You should try to find a lightly traveled road farther away from town if possible, or else you risk becoming roadkill yourself. Less-traveled roads are both safer and you will find less dead amphibians. Drive slowly, especially when you see frogs or salamanders crossing the roads.

Northern Leopard Frog found moving into a flood plane in late spring.

While in a car it is very difficult to spot certain species and it will take you a little while to develop a search image for amphibians, especially small ones like Four-toed and Red-backed Salamanders. The truth is that really small amphibians cannot be seen from a car traveling just 10 mph, let alone 50. The extremely small ones can't be seen from a car at all. Larger salamanders that are not moving often look like broken sticks that point up at one end and frogs that are not moving can look a lot like rocks. While driving around, if you find a good spot with with a couple large amphibians close together, it's time to park the car and check the road on foot with your flashlight. It is a good idea to wear reflective vests so passing vehicles can see you, and also to turn on your car's hazard lights.

Four-toed Salamanders are itty bitty and you'll never see most of them from inside a car. I found this one on foot with a flashlight after finding a few larger species from the car and deciding to get out and walk around.

If you roll down your windows and turn off the radio you can listen for frog choruses. Loud choruses close to the road mean it's a good spot to slow down or get out of the car. Many times people end up finding a good amphibian crossing site by accident while on the way to a place they identified on a map so keep your eyes and ears open even before you reach your target area.

Often you'll find males latched onto females long before they reach their breeding site, just in case there's too much competition in the water.

Here's a short material list of what you'll probably want to bring during your road searches. It's not all required, but it's what I bring. At the very least bring a flashlight, some sort of map (smartphone will do if you don't have something better), and something to write on:

A strong flashlight -- I like Maglites and handheld spotlights. Head lamps are useful but most are not strong enough to spot things well up the road. Most people I have spoken to who used a head lamp on their first road search switched to a more powerful flashlight on their second. 

Extra batteries -- this is especially important if you're not using an LED light. Most people use their house flashlight once in a while and only for a minute or a two at a time and go years between changing batteries. Take that same flashlight on an amphibian hunt and it's dead after an hour of use. Bring extra batteries.

Road atlas -- I cannot reccommend a Gazetteer state atlas strongly enough. I can find a good road crossing site way better using a Gazetteer than I can using the map app on my smartphone. If you don't have or can't find a good road atlas, you can use your phone or Google Maps, but you'll probably miss some stuff and obviously don't use your phone while you're actually driving; it's illegal most places and dangerous everywhere. Many atlases and road maps do not show wetlands other than lakes, large ponds, rivers, and streams. Gazzetteers show marshes and differentiate between woods and open fields on a large scale. You can also print maps from google of places you want to go (the areal imagery helps a lot!), but if you plan on driving around larger areas nothing beats a good atlas. Vehicle GPS units help as well, especially if you don't know where on a map you are, but they aren't very useful in finding road crossing sites.

Notebook -- A good field notebook is the best friend of anybody wanting to record their findings or submit reports to a conservation institution. Keep in mind that it will be raining so you will want a way to protect your notebook from the water or use one that is made with rain-proof paper. The brand, "rite in the rain" is great and you can get a decent notebook that fits in most back pockets for about $6 on amazon. As a bare minimum, the sorts of data you might want to write down include the date, location, time, species, and quantitiy. Other useful information might include weather conditions, the sex and size of each amphibian, and GPS coordinates..

GPS unit -- these come in handy if you ever want to get back to a spot off the road or if you wish to submit your findings to a state agency or atlas program. Coordinates will allow other people in the future to go back to that exact spot without needing to worry about ambiguous directions or changed street names.

Tupperwear container -- Or plastic baggies. These are useful to temporarily store amphibians to show other people or to observe while you identify the species. It allows for you to easily see the underside of salamanders and can be especially useful if you want to show a small salamander to kids, some of which do not have gentle hands. If you need to hold onto a salamander for more than a minute you should put it in a container with a little bit of water to minimize stress.

Field guide -- especially when you're just starting out, having a good resource to help you identify the amphibians you find is essential. It does not have to be a book, there are plenty of online resources to help you with ID and probably some apps, but having a book for the reptiles and amphibians of your region comes in extremely handy. The Peterson guide to the reptiles and amphibians of the eastern United States will get you by pretty much anywhere in eastern half of this country, but I like guides that are specific to smaller regions. For Vermont, I reccomend the New York guide and have recommended it for years. The Great Lakes guide is awesome too. 

Reflective vest: As a precaution it is a good idea to wear a reflective vest so you can be more easily seen by oncoming traffic.

Friend -- having a friend along to help makes a trip much more enjoyable and if you are driving, most importantly, they can help you navigate and get out of the car faster to catch a frog that is hopping across the road.

I brought a friend!

Don't forget to be safe! Use your best judgement and decide whether or not a road has too much traffic to be walked on safely -- you are out there to observe and help amphibians, but no amphibian is worth risking your own life. Also, be mindful about people's property and try to avoid getting out of the car in front of people's houses. Remember, you're walking around at the end of someone's driveway in the middle of a rainy night with a flashlight, which is suspicious and alarming to residents. Many people may call the police or come out to see what you are doing and not everyone is friendly about it. A homeowner is just as likely to greet you with curiosity as with hostility. On major roads or certain areas it might be unlawful to pull over on the side of the road and walk around. If there is any question about this you can call your local police department to make sure. In populated places or places where I have been approached by police or border patrol in the past I like to phone them in advance to give them a heads up that I'll be the creepy guy out on the roads doing suspicious things that night. If they get a call about some weirdo in the rain with a flashlight it will save them the time of following up on it and you the trouble of needing to explain yourself to law enforcement in the rain while they blind you with a flashlight that is probably much better than yours.

Other Important Stuff:
Many amphibians can secrete toxins from their skin when they feel threatened and these toxins, while not dangerous to touch, can irritate eyes or open wounds. Be sure to wash your hands at the end of a night and avoid rubbing your eyes after handling frogs or salamanders. Getting salamander goo in your eyes will not cause any long-lasting damage but it can cause a an uncomfortable burning sensation for 10 minutes or so.

After moving several hundred salamanders across the road I got an extreme case of salamander slime.  Seriously don't rub your eyes after handling Spotted Salamanders, Blue Spotted Salamanders, Jefferson Salamanders, or Gray Treefrogs.
You should be mindful also that because amphibians breathe through their skin, anything on your hands, such as bug spray, will be absorbed into an amphibians body and may cause them harm, or even death. The rule of thumb I like to use is that if something burns if you get it in your eyes, it should not be on your hands when you pick up an amphibian. Also, amphibians need to stay wet in order to breath so if one starts to feel sticky you should douse it with water or release it in a damp place.

Wash your hands before and after handling amphibians. Don't let the amphibian dry out.

Be prepared to see some sad stuff. You'll probably find dead and dying amphibians. Finding a dead salamander is one thing, but finding a severely injured animal thrashing around in the middle of the road can be really hard. Some people choose to put them out of their misery, others don't. I won't tell you what to do here, just be prepared to see it. 

Seriously wounded Northern Leopard Frog that was struck by a passing vehicle moments before my arrival.

Out on the roads you never know what you might find. You could find a species that has never been documented in that area or stumble upon one that is very rare, possibly even endangered. You might even find very rare color morphs, like this leucistic Blue-spotted Salamander:

Even if you do not have the good fortune of finding something unusual you can be guaranteed that somebody else out there will be interested to know what you do find. Most states have some sort of atlas or monitoring project and you can submit your findings directly to the people running those programs. Below is a short list of sites that have range maps for northeastern species and ways to submit your findings to biologists or databases for other people to use in the future toward the goal of conservation:

Vermont Herp Atlas
Pennsylvania Herp Database
New Hampshire Herp Atlas
Massachusetts Herp Atlas
New York Herp Atlas
Maryland Herp Atlas
National Herp Database

Looking for amphibians during the Spring migrations is a very rewarding experience and can be especially fun for children who will benefit greatly from being exposed to such things early on in life. Good luck out there, I hope I have provided you with enough information to get you started in your quest for migrating amphibians. If you have never done this before and give it a shot for the first time this year, I would love to know what you find. Remember, have fun and be safe!

In Vermont, your reports make Jim Andrews a happy man. Make him happy.