The right colour, at the right time, at the right place. That’s all that really matters when it comes to marine iguana mating season in Galapagos. This fascinating creature, a member of our BIG15 group of iconic species, displays an extraordinary array of visual and behavioural patterns during this specific time of the year! In this blog, we invite you to find out how they do it and why they do it!
Marine Iguana Mating Season: Environmental Cues
With the arrival of the hot season (Dec-May) comes many things in Galapagos, one of which is marine iguana mating season. At first glance, one might consider it rather peculiar for marine iguanas to begin their mating season during this relatively odd time of the year. Why inconvenient? Principally because water temperatures rise, meaning that the presence of nutritious algae in the ocean – one of the marine iguanas’ largest sources of food – drops substantially. In a nutshell, this means that marina iguana mating season begins right when food supplies are at their all-time lowest. But this is, in fact, part of their instinctual strategy, so to speak.
Marine iguanas, however, are pretty much prepared for this harsh period thanks to the fact that they stocked up tons back when Galapagos waters were pretty much overflowing with algae during the dry season (Jun-Nov). This means that if you come upon them at this point in the year, marina iguanas look comically plump. But this has a lot to do with what we’ll talk about in the following section regarding behaviour.
There’s an even more fundamental reason for why marine iguana mating season begins now, during the hot season, and it has a lot to do with just how optimal and ideal the environment is for laying eggs. Humidity and temperature are crucial factors in the success of their eggs, and increased levels of these two variables is exactly what the hot season entails. As a result, marine iguana mating season begins now, leading to some rather fascinating physiological changes in the process.
The most notable of these physiological adaptations is the mesmerizing shade of turquoise/teal that appears on the edge of the marine iguanas’ spine, their face and even their legs (particularly on Española Island). This serves as a visual indicator that marine iguanas are ready to mate and also leads to some pretty spectacular behavioural changes, too.
Behavioural Patterns: Males vs. Males & Females vs. Females
All the energy that marine iguanas have saved by stocking up on algae during the dry season is now put to the test. Males primarily invest their energy in doing two things: chasing tail and protecting their territory. These instincts manifest themselves in physical behaviours such as head bobbing, which serves as a signal to other that they’re ready to mate and that they’re also ready to defend their territory.
Females, on the other hand, invest this saved up energy into finding a suitable place to lay their eggs. A large amount of their energy is spent testing or “probing” different areas as they search for a suitable place to lay their eggs. They check for moisture and make sure there isn’t too much debris in the way of their nesting site. Once they find a perfect nesting spot, they dig a hole about 1-foot/0.3-meters deep to lay their eggs inside and then cover it. Worth noting is that the act of laying eggs entails a considerable consumption of energy, too. Females will also defend claim their nesting territory, if necessary.
The eggs that are laid are oval-shaped with a leathery, soft feel to them – squishy almost. This is a natural adaptation that helps foster embryo development, as their design creates a permeable layer through which water and moisture are able to get in and help with the development of the embryo.
Heat of the Moment!
The mating process between marine iguanas is rather violent in the sense and, in a certain sense, it has to be. It is an incredibly painful process of insemination for the female, which makes them understandably “reluctant” to partake in the act of mating. Consequently, the male must often grasp and pin the female down in order to keep her from squirming away from said act (and pain). Once this brief ordeal is over, the female will lay her eggs roughly five weeks later, laying anywhere between 6-8 eggs which will eventually lead to marine iguanas hatching. Hatching typically occurs around April/May of the following year, conveniently coinciding with the transition into the dry season, right as upwellings are bringing back nutritious algae to help feed this next generation of marine iguanas.
Interested in seeing these remarkable behavioural and physical tendencies during marine iguana mating season? Then be sure to hop aboard Yacht Isabela II’s numerous Galapagos itineraries to view them at the following visitor sites!
- Punta Espinosa (Fernandina Island) & Puerto Egas (James/Santiago Island) – Northern Galapagos Islands itinerary
- North Seymour Island – Central Galapagos Islands itinerary
- Punta Suarez (Española Island) – Southern Galapagos Islands itinerary
Information & Photography provided by Francisco “Pancho” Dousdebés – Galapagos Expert