Diamondback Terrapin Studies - Orientation for Surveyors

The lower Rahway River is a unique urban habitat that is under threat. One of the animals that continues to survive in this area is the Diamondback Terrapin. Thank you for helping us study our valuable wildlife and natural resources.

Please read this orientation before participating in your survey; it will make the trip on the river more enjoyable.

 

Looking west towards NJ Turnpike from lower Rahway River, Carteret. This estuarine marsh is the best left in Union County and one of best in Middlesex County. 

Orientation

Introduction - Rahway River Watershed Association and National Biodiversity Parks, Inc. shall likely have a small breakfast for you and some drinks at 0800 sharp 10/10/15 Saturday. Your paticipation in the survey helps send an important message that our rivers, wetlands and animals are important.

Lower Rahway River, 3 miles east of the Rahway River Yacht Club. The "Arch" property is pictured but is under threat by the questionable actions of the NJDEP Management and various local and state politicians.

General Information - There will be multiple boats/teams on the river with the purpose of counting terrapins, determining their sex and taking notes on their exact location and behavior. The entire lower stretch of the river including all side creeks must be surveyed in the same few hours on the same day to avoid double counting terrapins that may move from day to day or even from hour to hour.

Each boat team will be given a different section of the riparian corridor to survey; this avoids double counting of animals while concurrently the entire river and estuarine creeks are assessed. Data sheets for recording observations will be distributed at the orientation. Please fill out all the data boxes in legible handwriting. Please keep the sheets dry. Hand back the completed data sheets before you leave.



THINGS TO BRING (unless you do not have or can't borrow them for a few hours)

Canoe, Kayak or Small Boat
Life Preserver
Seat Cushion
Small Towel (to wipe paddle back-drip off your gear)
Small Cup (for bailing if needed)
Earth Colored Hat
Earth Colored Shirt
Data Sheets/Maps (NBP provides)
Binoculars
Camera (optional)
GPS (if you have)
Pencils and Pens
Clipboard
Snacks
Small Cooler (optional)
Drinks
Sunscreen (per your needs)
Insect Repellant (depending on season, NBP will have at orientation site)


Be careful of other boats on the river.  

Terrapin Senses - Terrapins have very good vision and can likely detect colors; so wear only natural earth colors like those that are seen in a marsh by terrapins (wear soft greens, camo, medium blues, light browns, dark tans---PLEASE DO NOT WEAR BRIGHTLY OR LIGHTLY COLORED HATS or SHIRTS--AVOID WHITE, REDS, ORANGES, YELLOWS, VIOLET, PINKS, BLACK, ELECTRIC GREENS AND BLUES, ETC.

Notice these earth colors--this team saw the most terrapins on the Rahway River. 



Good colors for hat, shirt and canoe

Good form...but a bit too much red although hat is good.  Name withheld.

Avoid if possible using brightly colored canoes and kayaks (unless that's all you have). Terrapins have keen eyesight--AVOID RAPID, SUDDEN and JERKY MOVEMENTS  OF THE CANOE, HANDS, HEAD OR BODY. Remember when dressing you are trying to remain unseen by terrapins versus rescued at sea by a distant helicopter at night!

Animals are very keen to avoid predators; you are perceived as a possible fatal threat. A terrapin often sees your head, hair and face first; these are black, blonde, red or very light tan. These are not natural colors so PLEASE BRING AND USE AN EARTH COLORED HAT.

Terrapins' hearing is muted but still keen, they can "detect" voices and feel vibrations caused by sounds/voices, your paddles or canoes. PLEASE DO NOT TALK LOUDLY, PLAY MUSIC OR "ACCIDENTLY" BANG YOUR PADDLES ON THE WATER OR CANOE.  

Terrapins likely have a keen sense of smell but his should not influence the success of your survey.

Correct Viewing Techniques - Most surveys are done in the morning when terrapins will often be in the water looking for food, desired salinity or swimming; you will only see their small heads as they breathe at the surface. If they detect there is something unknown or threatening to them (you/your boat) they may only be at the surface for a second or two. 

They may surface again soon after or they may swim a distance of up to 100 feet and resurface for air and to see what you, a perceived threat, is doing. Sometimes they will go to the bottom after the initial brief sighting and remain there for many minutes or even hours. Terrapins can stay under water for 4 hours in warmer water and even longer in cooler water. So you must be vigilant with your sight focus; if you miss that first brief sighting you may not see that terrapin again. Resultant is an undercount of the actual terrapins occupying the riparian corridor.

As the day warms up terrapins may bask on the gently sloping mud flats of either the main river channel or on the steeper banks of the marsh creeks that lead into the river. The fore-seated surveyor must be alert at all times especially when coming around close or distant bends in the river or creeks. Terrapins are startled when they see you; they will quickly submerge if they are on the water surface or run/slide into the water if on a bank, flotsam, logs or overhanging woody vegetation (bushes). 



Male placed on female terrapin (Terrapin Education Research Program of Savannah)

You must be very observant and "stalking" to see terrapins under most conditions. Your visual search image must be set at a minimum of 200 feet in all forward directions and angles. During each minute you should also glance behind and to the side to see if you have missed a terrapin or by coincidence the turtle surfaced soon after you passed that area. The river varies in width so there is often alot of habitat to your sides. A good surveyor covers all 360 degrees of the river as they slowly (1 MPH) and quietly paddle the river; they develop a logical and repetitive way of moving their eyes over the survey area. Rotate your eyes and head slowly  around the entire survey area, front and back, every minute. Then apply, rinse, repeat. Soon it will become second nature.

Binoculars are often great for seeing our quarry a bit earlier and better than with the naked eye. If you have a pair or two please bring them to share with your boat mate; scan out front and to the sides, and back 100 to 200 hundred yards away to spot the terrapins before they dive. Do not double count terrapins however.

Determining Turtle Species -  Brackish water presents an osmotic challenge to freshwater turtles; they will quickly dehydrate and soon perish in brackish/salt water. Diamondback Terrapins are the only brackish water turtle in the world. Rarely Snapping Turtles can be spotted in the lower Rahway River.    

Here below are pictures of each species profile at the water's surface and on land. Note that the Snapping Turtle has a pointier nose and higher eye arches than the terrapin; the terrapin has a much simpler, wedge shaped head compared to the Snapping Turtle.    



Snapping Turtle

Snapping Turtle

Diamondback Terrapin

Snapping Turtle

Diamondback Terrapin 

Determining the Sex of Terrapins - Adult female terrapins are much longer and heavier than males; this is called sexual dimorphism. There is no size overlap between adult females and males so the sexes can be easily separated by size even when they are in the water or at a distance (binoculars help).  Females' shells are 8 inches to 11 inches long while males are 4.5 inches to 6.5 inches. Females can weight 4 times the males.

Below are pictures/diagrams depicting the obvious differances between the sexes.



Male placed on female (Terrapin Education Research Program of Savannah)

   

If you have any questions, suggestions, comments, pictures or sightings please send them to our zoologist at NBP@comcast.net 

Thank You

Rahway River Watershed Association
National Biodiversity Parks, Inc.