As with any kind of field herping, being successful with road cruising depends on location, weather conditions, herp population density and a fair amount of luck.  Finding a good road can seem difficult sometimes because you tend to return to areas where you have had success. You could drive a really active road, but if the herps are not active at that time, you may not return. Conversely, if you have some luck on a usually inactive road, you may

Garter Snake crossing a dirt road in Hyde County, NC Photo by Scott Quint

Spotting a Good Road:

     A good road will have several consistent characteristics. Look for these things:

It will be travelled infrequently. Heavily travelled roads can be frustrating because there will likely be many dead animals on it. Also, it is more difficult to stop should you find something. There will always be someone wanting to pass you. Generally speaking, if the traffic frequency is high, there will be few animals on the road anyway.
It will cut through attractive habitat. This can be difficult to spot. Simply cutting through the woods is not always enough. Good habitat should also include a nearby water source. Also, some human activity is a plus. Look for roads that cut through slightly fractured habitat. The fracturing causes the animals to travel greater distances and to be more accustomed to crossing hazardous obstacles. Driving on roads that cut through undisturbed wilderness can be very frustrating because the herps have little reason to cross the road.
It will likely be relatively narrow. From the perspective of an animal that holds its head less than an inch from the ground, a road is a very large exposed area. A wide road is an obstacle that many animals will simply not risk crossing. Add to that the fact that most roads have right of ways that may also be paved and shoulders where the vegetation is cut. This vast expanse exposes the herp to predators and can be quite daunting. Narrower roads, especially where the vegetation is thick all the way up to the actual roadway are best. With a narrow road, however, comes shorter windows of opportunity to get to the animal before it disappears on the other side.

    Do not get unduly discouraged by:

• Lack of road-kills. Seeing large numbers of DOR's(Dead On Road) is a good indication that there is activity on a road, but lack of DOR's is not an indication of a lack of activity. Carcasses are often cleared by local predators and scavengers rather quickly. Also, if the road is lightly travelled, most animals can cross the road without incident. And, with the possible exception of snakes, most people will attempt to avoid hitting anything in the roadway.
• An unproductive day. If all the above characteristics are strong, visit the road several times and under several different weather conditions. I know of several great roads that took several visits before they proved to be productive. Also, in areas where the habitat is the same on both sides of the road, the incentive to cross may not exist, making crossing more incidental. Under these conditions, luck is a much more precious commodity.
• Human activity. I have found that light human activity (i.e.., residence or light agriculture) actually improves the chances of finding some herps. Human presence fractures the habitat and creates an environment where herps become accustomed to travelling longer distances. Also, human activity actually creates better habitat for some herps. Given a road where there is no permanent human activity and one where there are a few residences and perhaps a couple of one-acre farms, I would wager that the one with the activity would be consistently more productive, all else being equal.

Gauging the Weather:

     Depending on what it is you want to find, different weather conditions will have different effects on the herp activity. This will be true for ANY kind of herping. not only is the current weather important, but also the weather from the previous days and the impending weather conditions as well. There are too many combinations to identify them all here, but here are some general rules:

• Very cold is very bad. This should go without saying. Herps are ectothermic and cold weather reduces activity. However, it can be surprising how cold is "too cold". Given otherwise good conditions, nights with temperatures in the 60's(F) can still be productive. If the days are warm and rainfall has been consistent, a drop to 68F may of little consequence. Amphibians seem to be more tolerant of cold weather.
• Heavy rain is good or Amphibians. If the rain is falling hard, you will likely see nothing but amphibians and of those, mostly anurans. If it is during the day, you may get some turtles crossing. Otherwise, you will probably see no snakes or lizards in heavy rain unless it has been raining heavily for a long period of time. Long periods of heavy rain saturates the ground and can drive animals out. Also, lightning and thunder seems to spook the reptiles, but has little obvious effect on anurans.
• Very dry is bad for everything. Regardless of almost any other conditions, if the weather is and has been unusually dry, herps will go down into the ground and stay there. Animals that do not go underground will find a water source and stay there. Under these conditions, herps usually conserve energy and activity is infrequent. Quick bursts of precipitation may get some anurans moving, but likely nothing else.
• Clear skies: good and bad. Generally speaking, very clear daytime weather can be bad for alot of animals. When the skies are clear during the day, the direct sun makes many ectotherms on the east coast too warm even if the ambient temperature is mild. When the weather is really cold though, the direct sun will draw many animals out. Some snakes (i.e., racers, rough green snakes, hognose snakes, copperheads and diamondback rattlesnakes) actually like lots of direct sun, but most prefer partly cloudy skies if they are going on the move. Many lizards like the hot sun also, and turtles will come out for direct sun despite almost anything else. At night, clear skies can mean a bright night, especially when the moon is full or nearly full. This is important because night time predators can see the herps better when the skies are clear. This doesn't mean that herps do not come out when it is clear, it only means that they tend to expose themselves less so crossing roads is not as frequent.
• Moderate and consistent rainfall is good. This is generally true for all herps. Healthy, regular precipitation keeps temperatures mild and ground water abundant. So there are little or no (climatic)inhibitors to herp activity. Under healthy conditions, a light rain will stir many herps into activity. Under unhealthy conditions, light rain has virtually no effect on meaningful activity.
• Moon phase matters. There is a lot of disagreement on this, but my experience is that the moon phase is important. A new moon or a moon that is below the horizon is better than a bright, full and high moon. This is simply because predators can see better in the moonlight, and most herps are prey for many nocturnal predators. Obviously, moon phase means little for day cruising. Larger anurans still move in the moonlight at a greater rate than do snakes, but both move more frequently on unlit nights. Water snakes, I've noticed, still move on full moon nights, but only at dusk. Soon after dark they disappear.  As I said above, the animals still move, but

Road Crossing Frequency:

Corn Snake crossing by a chicken farm in Duplin County, NC Photo by Scott Matthew Quint

Mathematically speaking, road cruising can be a really bad way or a really good way to find herps. It really depends on what you want to find.      Anurans sit in the road for the purpose of catching insects. They sit in the road because it actually easier to see and catch their prey. When lizards sit in the road, it is generally for the same reason, but you usually will not see lizards in the road in the Coastal Plains. You will occasionally, but usually not. If you are looking for anurans, under good conditions, you will find plenty at night on roadways.

Roadkills

    An interesting feature of road cruising is that many herps are found dead. As silly a statement as this sounds, what makes it interesting is that the dead seem to frequently outnumber the living, even on low traffic roads. This is simply an artifact of the fact that a dead animal is effectively "frozen in time". Unless some scavenger cleans them up, the dead will remain and accumulate, while the unharmed animals will get off the road and never be seen.  On a low traffic road (a frquency of vehicle passing any particular point every 5 minutes - 10 minutes) you may never see a roadkill (or DOR), but there may still be plenty of herps. If there are a lot of DOR's, it is a good indication of a  lot of herps.

     Road kills can be heart-breaking to find because it is a shame that any creature die so needlessly. But regardless of how recently the animal was hit, you likely would never have seen if it had not been. Occasionally an animal is killed right before your eyes, and those situations are most frustrating, but the vast majority are more than a few minutes old and so the animal would have long been off the road before you came along. I am not saying that it was good it was hit so that the animal could be at least seen, I am saying that you should not feel cheated about it.

     Incidentally, road kills that are in good condition, should be collected and deposited at a museum along with the location data. These creatures can still be useful in death and there is much to be learned from them. A healthy roadkill collection at the museum can save many live animals from the pickle jar.

Sex Ratios:

     In the Spring, males outnumber females on the road with a ratio of about 4:1. As the year progresses, these ratios level off to near equal, but males still seem to outnumber the females slightly. Studies of various snakes in various localities throughout the country have shown that male home ranges are generally larger than female home ranges. This indicates that males will cover greater distances and, therefor, cross more roads. Spring is mating season on the east coast for most species, and so males are more active in general.

Conclusion:

     Road cruising is a game of chance, but the odds can be hedged. Given the cost of gas and the wear and tear on the vehicle, you should carefully consider when you choose to actually go out for the purposes of finding herps. Plan your trips carefully and mind the weather. By eliminating obviously bad conditions, you can conserve your resources for potentially better more productive tips and save yourself a lot of frustration.