While on Caamaño between May 7 and June 23, 1997 we [Jeffrey Sonnentag (entire time), Martin Wikelski (1 week), Mónica Freire Pesántez (entire time), Franz Kümmeth (all minus 9 days), Daniel G. Vergara Granda (app. 4 weeks)] continued our work aimed at identifying possible reasons for female mate selection in marine iguanas.  In order to accomplish this we had previously captured, permenently marked by branding, measured, and taken blood samples from territorial males and nesting females (January-March 1997).  To continue the work during this visit we captured hatchlings, marked them permanently by branding, measured them, and took blood samples.

Hatchlings were captured either by walking around the island's perimeter and capturing them with a noose made of fishing line or by finding them in fenced in areas we had set up.  Fenced in areas consisted of plastic from 2-3 feet high held in place by attachment to a rope tied between stakes at the top and weighted by sand at the bottom.

Permanent marking was accomplished by heating a paperclip and applying it to the body.  Locations of branding included both sides, the belly, and a straight mark ("1") on the tail near the base (usually on the left side while on its back).  The mark on the tail is intended to make it emminently clear that the marking occurred during this particular season.  Numbers used ranged from 1 to 602 without the use of 8's for a total of 488 marked hatchlings.  There is no 331 but instead a 329 with a line/bar under the numbers and number 124 has 123 with lines/bars under it on its sides.  Number 1 does not have any mark on the tail and 112 has 2 marks on the tail.

Following branding the hatchlings were measured.  Measurements included: snout-vent-length, hind leg length, tail length, head width, weight, number of spines on neck (consisted of large nubs),  depth that the sex probe indicated, number of ticks, and a number 0-3 indicating the relative number of mites found in the neck region.  A 0.25 ml blood sample was then taken and placed in a sealed tube containing EDTA, SDS, and Trizma Base for preservation.

Hatchlings were then taken to where we had a runway set up and a reflexive/speed test was made in the following manner: 1) hatchlings were painted with their identifying numbers and also around the perimeter of the top of the head and on both SIDES of the spines (paint on the neck not spines), 2) temperature was taken by placing a probe between the back leg and the body and holding the leg against the body for 10 seconds, 3) the hatchling was placed at the entrance of the runway and a slab of metal was struck 3 times with a hammer and the hatchling was released, 4) time that the hatchling ran and the distance that was run before the first stop were noted (with a maximum of 5.9 m - the length of the runway).

Location from which the hatchlings were captured was also noted so that they could be return to the same place.  While we were searching for unmarked hatchlings around the island we also kept track of where the marked hatchlings were (the particular section we had named - A-O), the zone (0-3, way out in the intertidal, on the rocks that get covered daily but with little algae, on the dry rocks, or in the bushes respectively), how many other iguanas were within 1 m, how many of those iguanas (all - male, female, other hatchlings) were marked (branded), and the activity the hatchlings were involved in (resting prone, resting with just head up, resting with head and body up, walking, head bobbing, head bobbing with mouth open, agonistic/fighting, or eating).

Following our return from the island the blood samples were brought to the United States for analysis (Loma Linda University, Loma Linda, CA).

While on the island we also recaptured all of the males that remained and weighed, checked for ticks and mites, and repainted them.  Also we recaptured about 60 females, weighed them, and checked them for ticks and mites.  They were not repainted.
 

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