All posts by Nick Herrmann

About Nick Herrmann

Nick Herrmann is a Ph.D. student in the Losos Lab at Harvard.

What Drives Substrate Use Patterns in Semiaquatic Anoles?

Anolis oxylophus at La Selva Biological Station (left, photo by Christian Perez) and Anolis aquaticus at Las Cruces Biological Station (right, posed).

Anolis oxylophus at La Selva Biological Station (left, photo by Christian Perez) and Anolis aquaticus at Las Cruces Biological Station (right, posed).

Among anoles, West Indian ecomorphs are the best known microhabitat specialists, but they are not the only ones. Semiaquatic anoles, of which there are 11 described species, live exclusively near streams and will sometimes enter water to feed or to escape a threat. The Central American species Anolis aquaticus appears to be specialized for climbing on rocks, particularly relative to other Central American semiaquatic anoles (Muñoz et al. 2015). Recent posts on A. aquaticus have addressed sleep site fidelity, dewlaps and trait scaling, and underwater foraging.

During a field ecology course with the Organization for Tropical Studies last winter, I compared patterns of substrate use between A. aquaticus and another Central American semiaquatic anole, Anolis oxylophus. Unlike A. aquaticus, A. oxylophus perches predominantly on woody and leafy substrates (Table 1). I wondered what was driving the differences in substrate use between these two species that appear broadly similar in morphology and lifestyle. Some Caribbean anoles alter their behavior to use only a narrow subset of available substrates in their habitat, whereas others have a greater breadth of substrate use that more closely reflects habitat-wide availability (Irschick and Losos, 1999; Mattingly and Jayne, 2004; Johnson et al., 2006). To evaluate whether substrate use differences between A. aquaticus and A. oxylophus are driven by substrate availability, species-specific selectivity, or both, I simultaneously quantified lizard substrate use and substrate availability within their streamside habitats.

Continue reading What Drives Substrate Use Patterns in Semiaquatic Anoles?

Age Structure of Invasive Green Anole Populations near Japan

Yasumiba et al 2016 Fig 1

Figure from a new paper by Yasumiba et al. illustrating how LAGs in the cross sections of bones can be used to infer lizard age.

Anolis carolinensis is a disruptive invasive species in the Osagawara Islands near Japan, a UNESCO World Natural Heritage site.  It was first recorded on the island of Chichi-jima in the 1960’s and has since spread to surrounding islands. A recent post on Anole Annals describes efforts to improve the effectiveness of adhesive lizard traps on the islands by using cricket bait.

A new paper by Yasumiba et al. improves our understanding of these invasive A. carolinensis by quantifying their longevity and growth rates using skeletochronology. Continue reading Age Structure of Invasive Green Anole Populations near Japan

Field Notes from Long Island, Bahamas

smaragdinus-and-sagrei

Anolis smaragdinus (left) and Anolis sagrei (right) from Long Island, Bahamas. The individual on the right is marked as part of selection study.

This past August, two field assistants and I went to Long Island, Bahamas to collect data on sympatric populations of Anolis sagrei and Anolis smaragdinus as part of a natural selection study. Our primary study area is a small island (approximately 1000 ft x 200 ft) in the middle of a lake with relatively high densities of both species. While in the field we observed some interesting behaviors that I want to share with the AA community in hopes that you will find them interesting as well!

1) Frugivory by anoles was common at our study site, which had an abundant supply of small berries from black torch (Ertihalis fruticosa) and small-leaved blolly (Guapira discolor).  Anolis smaragdinus was usually the culprit, although we did we did see one adult male A. sagrei eating fruit.

2) We captured (and released) over 150 unique A. smaragdinus and later re-spotted several of those individuals. During a typical eight-hour day, we encountered 15-20 individuals, a surprisingly large portion of which were a male and a female in the same tree. These instances made a particularly strong impression on me when they were separated by long periods of not seeing any A. smaragdinus. I can think of multiple occasions in which we found a couple together, saw no individuals for another three hours, and then suddenly came across another couple. In several instances, there were three individuals in the same tree. I’m not aware of green anoles mate guarding, and unfortunately the data I have don’t have the resolution to provide much insight here, but the pattern was definitely striking.

smaragdinus-cannibalism

3) We observed an act of cannibalism in A.smaragdinus, a species for which cannibalism has not previously been reported (although it has reported for the closely related A. carolinensis). We captured an adult female, saw that she was eating something, and proceeded to lose our marbles after pulling a hatchling (pictured) out of her mouth. Acts of cannibalism by female anoles appear to be rather uncommon (see page 30 of this Anolis newsletter), making this observation perhaps the most intriguing of our adventure!

Anole Adventures in the Cayman Islands

A sagrei on bluff - Cayman Brac NH

A. sagrei on Cayman Brac.

As part of an ongoing study of Anolis sagrei, recently posted about here with additional links therein, I had the pleasure of joining Anthony Geneva and Shea Lambert on a trip to Cayman Brac. We later met up with Graham Reynolds and his undergraduate student Amy Castle on Little Cayman, and closed the trip out with two days on Grand Cayman. Spending time on all three Cayman Islands was a real treat, in large part because of visually stunning anoles like Anolis conspersus and Anolis maynardi. These two species have received a lot of attention on Anole Annals. Rather than rewrite what’s already been written, I’ve decided just to share some pictures from the team. If you’d like to learn more, click on the species names above and explore to your heart’s content. Enjoy!

A conspersus - hotel NH

A. conspersus on Grand Cayman.

A maynardi - Little Cayman SL

A. maynardi on Little Cayman. Photo by Shea Lambert.

Continue reading Anole Adventures in the Cayman Islands

Spring Break Herp Style

 

group at night 1“This is not a Spring Break trip to Costa Rica, it is a herpetology class trip to Costa Rica that happens to be over Spring Break.” So said Jonathan Losos to a room full of eager students, many of whom had chosen to take Herpetology in part because of the adventure that awaited them. As first year Ph.D. students in the Losos lab, we were as excited as anyone for the opportunity to see some of Costa Rica’s rich biological diversity. Plus the well-publicized stereotype of how young people spend Spring Break has never really appealed to us. We’d rather be in the nighttime forest with a headlamp.

Anolis pentaprion 1

The lichen anole, A. pentaprion

The trip started with a day and a half at Veragua Rainforest. We saw tons of frogs and a handful of snakes, but anoles were hard to come by except for a few individuals along shallow, slow-moving streams (A. humilis, A. limifrons, and A. oxylophus). One of our most exciting finds of the trip was along one of these streams – an A. pentaprion hugging a narrow stem at eye level. It was shocking to see this lizard so close to the ground as it is often found high in the canopy and has even been observed gliding between perches. While many mainland anoles don’t fall clearly into the classic ecomorph categories, this lizard, with its small legs, long body and head, and slow but sneaky evasive behavior, is very reminiscent of West Indian twig anoles (and he’s got a gorgeous dewlap too! see photo at end of post).

From Veragua we moved to La Selva Biological Station where we spent five action-packed days exploring the forest and documenting the herpetofauna. Continue reading Spring Break Herp Style

Anolis sagrei on Rum Cay, Bahamas

Anthony and Kevin near the golf cart. This inland forest was the tallest we could get access to on the island.

Anthony and Kevin near the golf cart. This inland forest was the tallest we could get access to on the island.

A July trip to the Bahamas to sample Anolis sagrei has been documented in recent posts by Graham Reynolds and Kevin Aviles-Rodriguez. During that trip, Kevin, Anthony Geneva, and I traveled to the island of Rum Cay to collect data on anoles. With a human population of fewer than 50 clustered in an around the southeastern town of Port Nelson, Rum Cay is mostly uninhabited. Access to a majority of the island’s 30 square miles is facilitated by narrow dirt roads, several of which, particularly those on the western half of the island, are overgrown and unnavigable. Our golf cart, well-equipped with off-road tires, was pushed to its limits as we strove to find lizards across several habitat types on the island.

L. loxogrammus on Rum Cay. Photo by Anthony Geneva.

L. loxogrammus on Rum Cay. Photo by Anthony Geneva.

Anolis sagrei was abundant among most of the island’s vegetation including forests, mangroves, and beach scrub. Their mostly red dewlaps appear similar to those we saw on nearby Long Island. In each habitat, the lizards were usually perched within 1 meter of the ground but were occasionally found on the ground or perched higher than 1 meter. One exception was a shrubby forest located at (23.66501, -74.868245) which contained abundant A. sagrei along with incredibly high densities of the San Salvador curlytail lizard, Leiocephalus loxogrammus. Here we didn’t see any A. sagrei on the ground despite being present at the site for several hours on two separate days. Not an easy place to get to, but it would be a great site for studying curlytail behavior and interactions between curlytails and anoles. In our adventures we also encountered several Anolis distichus, with more on that to come in a later post.