In the fall of 2017, Hurricane Maria ripped across the island of Puerto Rico leaving devastation and destruction in its wake. This caused major changes in the structural environment of forests with unknown consequences for the animals living in them. Kevin Aviles-Rodriguez, a PhD candidate at UMass Boston, wanted to know how the hurricane impacted Anolis cristatellus island wide. Specifically, Kevin was interested in knowing if lizard morphology was altered by the hurricane and how morphological changes differed in urban environments and as time passed post-hurricane.
Here on Anole Annals, we have talked a lot about hurricanes and anoles, most recently related to morphological shifts in Anolis scriptus following hurricane Irma in which Colin Donihue and colleagues observed morphological shifts in limb length and toepad size. Kevin wondered if the same shifts had occurred in A. cristatellus following hurricane Maria, but taking things one step further reasoned that since urban and forest environments differ in structural habitat, that morphological shifts following the hurricane might differ as well.
Hurricane Maria made landfall in the southeast of Puerto Rico and then traversed the island diagonally, causing widespread and lasting destruction.
Kevin resampled the same populations (which I had previously sampled in my own research) at 4 and 11 months post-hurricane. He found that immediately following the hurricane lizards in both urban and forest populations had relatively shorter forelimbs, relatively smaller toepads, and smaller body sizes compared to before the hurricane, and that this effect did not differ between urban and forest populations. These results were contrary to what Kevin expected since recent researchby Donihue et al. found that following hurricane Irma, A. scriptus had relatively longer forelimbs and larger toepads – traits that would increase gripping ability during high winds. Similar to Donihue, however, Kevin also found that the lizards had relatively shorter hindlimbs. As Donihue and colleagues elegantly demonstrated with their leaf-blower experiments, longer hindlimbs are disadvantageous during hurricanes because they increase the surface area exposed to the wind and act as sails, blowing the lizard more easily off the perch. Interestingly, within 1 year of the hurricane when Kevin again resampled these populations he found that all trait values had increased again to their pre-hurricane values in both urban and forest populations.
Kevin emphasized that the shift in trait means at each time point was small but significant. Importantly, the lack of difference between how forest and urban populations responded (both experienced decreases in mean trait values) suggests that despite structural habitat differences the hurricane imposed similar selective pressures in both habitat types. Kevin continues to dig into morphological variation of urban and forest populations post-hurricane and I look forward to seeing the published results!
Satellite imagery of when the lights went out in the brightest region of the Caribbean.
You have probably heard about the hurricane’s effect on humans: months of ensuing darkness, destroyed roads, houses leveled and roofs torn clean off, no fresh water, and significantly crippled infrastructure and public services leading to over 1,000 lives lost when it all was over.
I’ve been back to the island now twice since the hurricane, once in January of 2018 and once last week (November 2018).
Four months post-hurricane
The destruction to both urban and forest areas was jaw-dropping when I visited in January to help Kevin Aviles-Rodriguez (UMass Boston) launch a project on urban lizard recovery and natural selection following hurricanes. (Side note – this research has yielded some really intriguing results so far and I look forward to Kevin sharing those with us here at Anole Annals in the future!) On that trip, four months after the hurricane, I found the island in disrepair. Many people still had no power or clean water, stoplights and electrical lines dangled from their snapped poles island-wide, roofs were covered in blue tarps, and driving involved dodging car-eating potholes, downed power lines, and debris. Most stores and restaurants were closed and many roads were impassable.
A stand of trees on the west coast four months post-hurricane (near Rincón).
The trees left standing in urban areas were bare toothpicks. I’m told that immediately following the hurricane, the leaves looked like green snow coating the ground several inches thick. Most of the trees that survived were the large and common urban species: mango, flamboyán, ceiba–leafless but still rooted. When we visited the forests I was equally shocked by the destruction: trees looked as if someone clipped them all off clean around 15 feet up, the canopy was gone and all of the large trees like Cecropia and Cocoloba were downed. Lianas had taken over giving the forests a bushy, surreal appearance. I left the island that January wondering how long it would take to recover; the human side and nature side alike had a long road ahead of them.
What was once closed-canopy secondary forest on the north coast (near Arecibo).
Fourteen months post-hurricane
When I returned last week, now 14 months post-hurricane, I was pleasantly surprised to see the island was recovering. Roads had been repaired, power had been restored, stoplights were working, debris had been cleared, restaurants and stores were open, and houses rebuilt. From the human side of things, the island seemed to be recovering. On the west side of the island, the leaves of the large trees had returned. Forested areas had more dense understory than typical and the canopy was still fairly open, but overall it seemed like the forests and urban areas were both returning to normalcy. I found many urban lizards without a problem, including Anolis cristatellus, A. pulchellus, A. stratulus, Ameiva exsul and the non-native green iguana. I was surprised however, that the nights were eerily quiet. The familiar ear piercing chorus of coqui was reduced to intermittent calls of only a few individuals. The coqui don’t seem to have recovered quite as well as the anoles.
No trees? This urban A. cristatellus seems okay with that.
Anolis cristatellus
Anolis pulchellus
Many challenges certainly still face the residents of the island, but it was starting to look more like the Puerto Rico I knew. So it was quite a shock when I visited the newly re-opened El Yunque National Park. El Yunque was hit particularly hard by the hurricane as the first landfall was just south of the forest near Yabucoa. Strong bands of wind pummeled the area, leading to massive landslides that closed the rainforest for months. The national park website said that only La Coca falls and Yokahu Tower were open to visitors, but I found a park ranger who informed me that the Mt. Britton trail was open (and the road to the peak of El Yunque had been cleared as well, though not the cloud forest trail).
As I drove up the mountainside to the Mt. Britton trailhead I was shocked at how open the forest was. When we arrived at the trailhead, my jaw dropped. The canopy had not recovered at all. The palms seemed to be the only trees that survived. I’ve hiked this trail many times, but this was the first time I did not wear a long-sleeve shirt – it was hot and dry. Perhaps the lack of animals shouldn’t have come as a surprise then. I didn’t hear a single coqui call while hiking the trail, where in the past we would hear many different species along the route. I also did not see a single Anolis gundlachi, where before my favorite trick was to tell someone that I could make lizards appear on demand then reach out and snatch one off a tree – they were that common! I did see a handful of Anolis evermanni, but only a few. Below are a couple of before and after photos of the same portions of the trail.
Mt. Britton trail in January 2017
Mt. Britton trail now, 14 months post hurricane
The entrance to the Mt. Britton trail before the hurricane…
and the same location 14 months after the hurricane
The impacts of hurricanes on wildlife
Recent research has shown that the insect populations of El Yunque have been declining for years, and certainly hurricane Maria did not help this situation. Perhaps the anole and coqui populations have suffered because of a collapse of food resources? Or perhaps the microclimatic shifts were too much for the lizards to handle? Anolis gundlachi does have a strong affinity for cool and moist habitats and it seems quite likely that with the current state of El Yunque, very little suitable climatic habitat exists for this species. Or perhaps the hurricane itself reduced the anole populations. Recent research on Anolis scriptus found that hurricanes can pose strong selective pressures leading to phenotypic change. Whatever the reason for the apparent decline, I am eager to check back in with the lizards in a few months when I visit again and even more eager to hear about the research of those studying herpetofaunal hurricane recovery.
No A. gundlachi to be found at El Yunque 14 months after the hurricane, but quite a few A. evermanni like the one seen here.
Are you studying the effects of hurricanes on lizards? Are you studying the recovery of Puerto Rican herpetofauna after Maria? We would love to hear more about it! Let us know in the comments, or consider contributing a blog post to Anole Annals.
Hurricane Irene, predicted to reach Category IV status, is now bearing down on the Bahamas from the south. And if you examine the hurricane’s track, you’ll see that she is aiming right at our study sites. What will happen? In the past 13 years, we’ve had three experiments terminated by hurricanes. Please cross your fingers, toes, and any other extremities in hopes that fourth time is a charm.
