The Ecology and Conservation of the Aruba Island Rattlesnake, unicolor.

Howard K. Reinert1, Lauretta M. Bushar2, and R. Andrew Odum3

1Department of Biology, The College of New Jersey, Ewing, NJ 2Department of Biology, Arcadia University, Glenside, PA 3Department of Herpetology, Toledo Zoological Society, Toledo, OH Aruba: Sun, sand, surf …… and special …. SSSSS!

Aruba Island Rattlesnake Aruban Cat-eyed or Cascabel or Santanero The only home of the Aruba Island Rattlesnake From 1993 to 2008: 198 Aruba Island Rattlesnakes were captured, examined, PIT tagged, and released. Most were examined very closely! During this time period 57 snakes were monitored with radiotelelemetry for periods of up to 3 years. These efforts resulted in 3,656 telemetrically-assisted observations of the ecology and behavior of free-ranging Aruba Island Rattlesnakes. The current distribution of the Aruba Island Rattlesnake encompasses 76 km2 of the 175 km2 island.

 Noord N

 150 m Oranjestad 100 m 50 m  Santa Fontein Cruz Hooiberg (166 m) Formerly Described Range Current Range

Jamanota (189 m)  Savaneta  San Nicolas 2 km Punta Basora Principal Components Analysis of Structural Habitat Variables

Habitat Variable First Principal Component Foliage Density to 1 m 0.905 Foliage Density to 2m 0.766 Distance to Cacti 0.118 Distance to Woody Plants -0.275 Distance to Rocks 0.464 Canopy Closure 0.604 % Surface Vegetation 0.836 % Rock Cover -0.386 % Leaf Litter Cover 0.388

% Soil Exposed -0.599 Habitat Use by Aruba Island Rattlesnakes

MALE RANDOM FEMALE

INCREASING SURFACE VEGETATION AND CANOPY INCREASING EXPOSED SOIL AND ROCK Preferred Habitat of Aruba Island Rattlesnakes Spatial Statistics for Aruba Island Rattlesnakes

Mean Total Mean Distance Minimum Sex Distance Moved Moved/Day Convex Polygon (m) (m) Area (ha) Male 2021.0 26.1 8.4 (n = 30) (±314.43) (±5.04) (±2.46) Female 1142.6 11.2 3.4 (n = 27) (±194.05) (±3.18) (±0.53)

• Males demonstrated significantly larger values for all spatial parameters (P < 0.05). • Values of spatial parameters are approximately half that exhibited by Timber Rattlesnakes in Pennsylvania. Movement patterns of a female and a male Aruba Island Rattlesnake BEL58 – female n = 59 days Total distance = 889 m Distance/day = 16.2 m Convex Polygon Area = 1.85 ha

BEL74 – male n = 98 days Total distance = 4212 m Distance/day = 43.0 m Convex Polygon Area = 22.1 ha Activity range and movement pattern of a female Cascabel (BEL5) over 316 days (8/14/93 – 6/26/94). Activity range of a male Cascabel (BEL3) over 312 days (8/6/93 – 6/14/94) and locations over the next two years. Translocation of 500 m had little impact on behavior.

BEL98 - translocated

BEL98 - native The Diet of the Aruba Island Rattlesnake

Prey Number Percent Aruban Whiptail 14 42.4% House Mouse 8 24.2% Cottontail Rabbit 4 12.1% 3 9.1% Vesper Mouse 2 6.1% Black Rat 2 6.1% Foraging positions:

Often associated with flowering and fruiting bushes or trees and sometimes… a dead goat. Does the Aruba Island Rattlesnake has a chance for survival? Arikok National Park (35 km2) was established in 1997. It contains nearly half of the habitat occupied by the Aruba Island Rattlesnake.

 Noord N

 150 m Oranjestad 100 m 50 m  Santa Fontein Cruz Arikok National Hooiberg (166 m) Park Boundary Current Range

Jamanota (189 m)  Savaneta  San Nicolas 2 km Punta Basora Protection of rattlesnakes and restoration of habitat needs to be a primary goal in Park management. Annual mortality of adult Cascabels based upon the Trent and Rongstad Estimator and a 365 day active season.

SAMPLE NUMBER TOTAL ANNUAL GROUP SIZE DEAD RADIO-DAYS* MORTALITY

Males 14 4 2838 40.2%

Females 14 8 2633 67.1%

Overall 28 12 5471 55.1%

*1 Radio-day = 1 snake monitored for 1 day Identified Causes of Mortality

Vehicles* 8.3% Goats & Donkeys* Malnutrition 16.7% 41.7%

Humans* 25.0% Unknown 8.3%

*50% of Cascabel mortality can be reduced or eliminated! Controllable Sources of Rattlesnake Mortality

. Traffic-related mortality . Mortality due to feral goats and donkeys . Degradation of habitat by feral livestock . Purposeful killing and collecting by humans Goats and Donkeys Kill Rattlesnakes and Degrade the Habitat

Populations need to be reduced or eliminated within the Park. Killed by:

Donkey

Goat Roads are Dangerous for the Cascabel

•Cascabels do not avoid roads •They are slow-moving •They often stop moving when a car approaches The Result: Reduce Road Mortality

. Strictly enforce a low speed limit. . Restrict vehicular traffic (including ATVs) to limited areas of the Park. . Close all park roads to unauthorized vehicles after sunset and before sunrise. . Post road signs at regular intervals along all park roads:

“SLOW - WILDLIFE CROSSING” Awareness Will Help SLOW

WILDLIFE CROSSING Education also needs to be a major part of the conservation program for Cascabels Educate and Inform

. Post regulations at park entrances and interior locations (trailhead parking areas, caves, beaches) “It is illegal to disturb, harass, remove, or kill any or plant within the Park” . Create Brochures/Guides -regulations guide -wildlife and plant identification guides -history, natural history and geology information sheets . Training Programs for Park rangers/private tours guides. Aruba Snake Brochure

S ANTANERO B OA C ASCABEL (Leptodeira bakeri) (Boa constrictor) (Crotalus unicolor)

The slender Santanero or Aruban Cat-eyed Boas are Aruba’s largest snakes. The The small Cascabel or Aruba Island Snake is typically less than 50 cm long. This longest Boa found on the island was slightly Rattlesnake averages 70 cm in length. The snake is recognizable by the large scales on less than 3 m. Newborn Boas average 35 cm. body color is often uniform gray or light the top of its head and by its pattern of dark Boas are not venomous. The most distinctive brown. There may be a faint pattern of brown bands alternating with light brown feature of a Boa is its pattern of dark brown diamond shaped markings on the back. This bands. The belly is plain white or cream and tan blotches which become red toward pattern is most noticeable on younger colored without any markings. the tail. The belly in white or cream colored snakes. The most distinctive feature of this This snake is shy and not aggressive. with numerous black spots. snake is the rattle at the end of its tail which However, it has enlarged teeth at the back Boas are excellent climbers and may be makes a buzzing sound when the snake is of its mouth and mild venom which is not found in trees and cactus. Boas also hide in alarmed. dangerous to humans. However, the venom the leaves under bushes waiting to catch Cascabels are shy and not aggressive, but can paralyze small and frogs. prey that pass. Boas catch their prey with their venom can be dangerous to humans. It Santaneros are most active at night when their teeth and then constrict it in their is best to leave this snake alone. Do not they search for food. During the day, they coils. The Boa’s diet consists of , attempt to catch or kill it. hide under rocks or leaves. They frequently lizards, rats, mice, and rabbits. Large Boas Cascabels hunt by waiting under bushes climb trees and cactus. Santaneros eat toads, have been known to eat small goats and and fruiting trees to catch passing lizards, frogs, insects, and lizards. chickens. When threatened, Boas will hiss mice, rats, small rabbits, and an occasional You may find Santaneros near dams loudly. bird. during periods of rainy weather or crossing Boas are a non-native . The first This is often considered to be one of the roads at night. This snake is found island Boas were reported on the island in 1999. rarest rattlesnakes in the world. The range of wide. Since that time they have been found across the Cascabel is restricted to the rugged and the entire island in all types of habitats. mountainous areas of the island mostly within Arikok National Park.

Monitoring and Research

• Establish a long-term monitoring program • Respond to Cascabel sightings • Relocate reported Cascabels – short distance translocation is safe • Continue basic research Especially - Assess the threat of the invasive Boa Constrictor to the Cascabel and other native fauna.

Can they live together on “One Happy Island”? Acknowledgements Field Biologists: Gian L. Rocco, Zach Felix, Mike Torroco, Matt McCort, Robert Rupert, Jr., Jan Piet Bekker, Robert Smit, Diego Marquez, and Matt Goode Logistic support: Aruba Department of Agriculture, Husbandry and Fisheries: T. Barmes, S. Vrolijk, T. Damian, P. Portier, F. Franken Arikok National Park: D. Arrends, A. Cruiel, S. Franken, R. de Kort, E. Croes Aruba Veterinaire Dienst: E. de Cuba, P. Barendsen, T. Wools Funding support: American Association of Zoological Parks and Aquaria, Coastal Oil Corporation, ESSO Petrolera, S.A., MetaCorp, the Toledo Zoological Society, and the College of New Jersey. • Our research continues.

• After 15 years, this is only end in sight. Thank you. Questions?