Terrapin Mating in Full Swing on Outer Cape

Male Terrapin in Outer Cape Mating Aggregation

May 2nd brought perfect turtling conditions to Outer Cape Cod with bright sunshine, a light breeze and a noon astronomically low tide.  Visibility in the South Wellfleet mating aggregation was exceptional as illustrated by the photograph above as this male diamondback terrapin swam through the clear tidal water.  We sampled turtles in this prime Outer Cape mating aggregation to assess the level of activity in this late spring season.  We discovered, unsurprisingly, that love is in the air … and in the water, too … on Outer Cape Cod.

Rufus the Turtle Dog Tracks Male Diamondback Terrapin

In less than 30 minutes, with Rufus’ help of course, we captured and processed 22 turtles, all mature adults.  No prepubescent juveniles were observed.  Ten turtles were marked specimens; 12 were new and had never been seen before.  Netting that many turtles in so short a period of time is an indication both of the level of mating activity and the perfect conditions.  Notice Rufus tracking the male terrapin in the lower right corner of the picture.

Female Diamondback Terrapin #834

Of the ten known turtles, several were old friends.  Female Diamondback Terrapin #834 has been tracked by the Turtle Journal team since 2000.  We’ve learned a great deal about this lady in the last 13 years.  We know that she nests on dirt roadway Way #100 on Lieutenant Island and now we know her mating aggregation location.

Terrapin #834 Emerges from Brumation in 2009

Terrapin #834 is one of the first terrapins in Wellfleet Harbor to reveal her brumation site.  The “before and after” pictures from late April 2009 show Terrapin #834 as she emerged from winter brumation in Wrong Step Creek near the Lieutenant Island causeway.  The black ooze visible in the picture on the right is the spot where the Turtle Journal team watched her rise from the primordial ooze.

Male Diamondback Terrapin #8127

We were a bit surprised by the ratio of 15 males to seven females, especially since in capturing terrapins there is a decided bias in favor of netting the larger females.  Male terrapins are just a tad more than half the length and less than a quarter of the mass of female terrapins.

Female Diamondback Terrapin #118

Another old friend we found was Terrapin #118, the Grande Dame of Wellfleet Bay Wildlife Sanctuary.  She has been observed in our longitudinal study since 1988; that is, for the last quarter century.

Female Terrapin #118 with Distinctive Forked “Devil’s” Tail

Terrapin #118 nests along the Sanctuary’s Goose Pond Trail and she is easily recognizable because of her distinctive forked (Devil’s) tail, documented since her first sighting in August 1988. 

We hope to see Terrapin #834 nesting on Lieutenant Island in early June and Terrapin #118 strolling along the Goose Pond Trail on a nesting run around the same time.   Then, with any luck, we’ll observe a repeat performance in early July for the second nest of the season for each of these ladies.

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