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About Author: Jeff Lemm

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Drought: Reptiles Don’t Like It, Either!

A cell phone photo taken of the habitat at the Safari Park Reserve in August 2014 shows just how devastating the drought has been on our local habitats.

A cell phone photo taken of the habitat at the Safari Park Reserve in August 2014 shows just how devastating the drought has been on our local habitats.

The drought has been awful for Southern California residents: dry, hot days, water restrictions, and a brown landscape. These are things we can all live with, but for our resident native reptiles and amphibians, drought can be a life-or-death situation. I have been working in the San Diego Zoo Safari Park’s Biodiversity Reserve (a 900-acre area adjacent to the Safari Park) for 15 years studying the reptile and amphibian species that call it home. This year I began a project studying a relatively rare coastal sage scrub species, the coastal patch-nosed snake Salvadora hexalepis virgultea. My plan was to capture at least 10 animals and implant them with radio transmitters so I could follow their movements and study their ecology. On normal rainfall years I see an average of eight of these wonderful snakes, so I figured that if I actively searched for them, I would be able to get a good sample size to study. However, I did not count on the drought being so intense.

Snakes get most of their water from the food they eat, and when there is no water, the food disappears as well. Many of our small, native animals tend to stay underground during such “tough times” and await better weather. Not only did many of the prey species disappear over the spring and summer, but the snakes also stayed deep underground to conserve moisture. Some snakes and other reptiles came to the surface for a brief period during the breeding season (April through June), and I was able to find a couple of patch-nosed snakes for my study. Unfortunately, reptile activity ceased altogether soon after. On a good spring day in a year with normal rainfall, I can find up to 20 snakes belonging to 8 to 10 different species in a single day. This year, in stark contrast to normal expectations, my best snake day yielded just two snakes. In addition, I spent nearly every day in the field for seven weeks in May and June and only saw two rattlesnakes. As the summer progressed and the habitat became more and more dry, very little lizard and snake activity was observed.

A red diamond rattlesnake found during a cover board array survey in 2010 at the Safari Park Biodiversity Reserve shows how lush and green the hills were that year.

A red diamond rattlesnake found during a cover board array survey in 2010 at the Safari Park Biodiversity Reserve shows how lush and green the hills were that year.

August is often our driest month, so we rarely see many animals in the field at that time. We often wait until late September before we start seeing hatchlings and juveniles along with occasional adult animals. This year, the young snakes have been virtually nonexistent, and that makes sense. If the adult female snakes and lizards cannot gain enough body mass, they generally will not reproduce. Since most of our wild animals stayed underground for much of the year, they probably did not feed and therefore were unsuccessful in breeding.

Last week I saw firsthand how difficult the drought has been on our native snakes. While walking through the coastal sage, I found a large, female red diamond rattlesnake Crotalus ruber. She was very thin and could barely move. I presume she had recently given birth (rattlesnakes in San Diego County give birth to live young in August and September) and just did not have enough body mass to make it through her pregnancy. No baby snakes were found in the vicinity, and I can only hope this female pulls through. If she had babies, they will, hopefully, be able to hold out until the rains eventually arrive.

A cell phone photo shows an emaciated red-diamond rattlesnake at the Reserve in September, 2014. Many of our local reptiles and amphibians are suffering from the recent drought.

A cell phone photo shows an emaciated red-diamond rattlesnake at the Reserve in September, 2014. Many of our local reptiles and amphibians are suffering from the recent drought.

In over 30 years of field “herping” (searching for reptiles and amphibians), I have not experienced drought conditions worse than those seen in 2013 and 2014. In fact, the North American Field Herping Association has shown just how bad the drought has been on Southern California snakes. When comparing non-drought year data from July 1, 2010, to June 30, 2012, with drought year data from July 1, 2012, to June 30, 2014, for snakes found in Los Angeles, San Diego, Orange, San Bernardino and Riverside counties, 4,971 snakes (1,055 hatchlings) were found between 2010 and 2012 whereas only 2,888 snakes (680 hatchlings) were found from 2012 to 2014. It is also interesting to note that there were more contributors to the database in the latter years, so roughly half the snakes were found by considerably more field herpers in the drought years than in the normal rainfall years, and roughly half the hatchling snakes were found in the drought years than in the normal years.

Here's a portrait of a healthy long-nosed snake in the Safari Park Biodiversity Reserve in 2009.

Here’s a portrait of a healthy long-nosed snake in the Safari Park Biodiversity Reserve in 2009.

So what does this all mean? Nobody can be certain right now. We do know that our climate has boom and bust years and drought and rainfall totals are very cyclical for most areas of the world. However, our findings to date do suggest that climate change is occurring at a rapid pace, and we all need to do our part to protect the environment and our natural resources, especially the snakes!

Jeff Lemm is a senior research coordinator in the Behavioral Ecology Division of the San Diego Zoo Institute for Conservation Research.

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A Significant Blue Birth

The San Diego Zoo’s Applied Animal Ecology Division is pleased to announce the hatching of a critically endangered Grand Cayman blue iguana Cyclura lewisi. This little female iguana hatched out of her egg on September 13, 2008, after an incubation of 92 days at 86.5 degrees Fahrenheit (30.3 degrees Celsius). She weighed only 1.58 ounces (45 grams) at hatching—a tiny little girl compared to males of her species that can grow to over 18 pounds (8 kilograms) as adults! Although our little girl is gray in color now, as most hatchlings are, adults of the species can become a beautiful powder blue color.

This iguana was a very lucky animal. About three-quarters of the way through incubation, her egg formed a small crack and started to leak fluid. This is a rare occurrence and can be caused by too much humidity, a thin shell, or many other factors. I patched the shell with plastic wrap and tissue glue and crossed my fingers. A few weeks later, I got the word that the iguana had hatched, and I ran over to the incubator room to see her. She looked good, although she had a distended belly, which usually means she hatched a bit too early and wasn’t able to absorb all of her yolk. I took her to the vets at the Harter Veterinary Medical Center, and due to the distended belly and a slight injury to the eye that probably happened during hatching, we decided she would stay with the vets. Internal yolk can usually absorb on its own as long as the animal is kept quiet and warm, but sometimes it can become infected and can even be lethal. After a week of excellent veterinary TLC, the little iguana absorbed her yolk, and her eye was healed up. She is currently waiting to be housed in the new iguana building that is near completion in an off-display area of the Wild Animal Park (stay tuned for that blog!).

Grand Cayman iguanas are considered to be the most endangered lizard in the world. Loss of habitat, introduced predators, feral animals that compete for resources, and cars all contribute to the iguana’s decline. At one point, there were as few as 20 animals left on Grand Cayman, but thanks to captive breeding, headstart and release protocols, and a new reserve system on the island, Grand Cayman iguanas are slowly starting to repopulate the wild.

Jeff Lemm is a research coordinator for the San Diego Zoo. Read Jeff’s previous blog, Frog Blog—What’s Hoppenin’?