Monday, 23 July 2012

Marine Iguana Lek

We were in the Galapagos in January travelling on the motor yacht Cachalote as part of an excellent Naturetrek tour led by Darwin Alvarez. January is an excellent time to visit the Galapagos — the sea is relatively calm, the daytime temperature not too high, the rains are turning the hillsides green and many animals are breeding.

A basking male Marine Iguana on Fernandina

January is the height of the breeding season for Marine Iguanas (Amblyrhynchus cristatus). I had never seen this species alive before despite writing about its salt gland in the 1970s.
After an early morning landing from a panga at Punta Espinoza on Fernandina (Narborough in the old British nomenclature of the islands), we found the Marine Iguanas in the full swing of displaying and mating. On a flattish, large lava bed tens of males were displaying. Females were coming to this site and some were mating. I suddenly realised that what we were seeing was a lek. I could not recall seeing anything about lekking in the guide books and so had to wait until I could do a Google search to see if lekking had been described in this species. Of course, it had — but not until the 1990s, and was the first species of reptile in which this behaviour had been discovered.
Here are some links to accounts of lekking in the Marine Iguana:

I spent some time taking video of Marine Iguanas on Fernandina as well as on the other islands. You can see the area of the lek about half way through this video of mating marine iguanas, as well as shots of the males displaying.

Fierce territorial disputes were also in progress and the next video, taken a few hundred yards from the scene of the first, shows one such dispute:

Incidentally and surprisingly, despite being a major destination for wildlife and general tourism and the excellence of the local guides, there is no really good field guide to the birds and reptiles of the Galapagos.