LeafThe Magazine of TreeLitter Walkers International and Amphibian Conservation EDITOR Ron Skylstad Leaf Litter VOLUME 4 | ISSUE 1 ASSISTANT EDITOR Ed Kowalski 1 FROM THE EDITOR 2 AMPHIBIAN HEALTH AND NUTRITION PHOTO EDITOR 5 FOLIUM Tim Paine FEATURES • 11 The Darwin’s Frog Conservation Initiative TWI DIRECTOR Ron Skylstad 20 Innovation in Conservation: The Case of the Strawberry Poison Dart Frog TWI PROGRAMS DIRECTOR Brent L. Brock 26 Islands in the Sky 40 Developing a Captive Breeding Protocol for Georgia’s Blind Salamander (Haideotriton wallacei) at the Atlanta Botanical Garden MISSION STATEMENT Tree Walkers International supports the protection, conservation, and restoration of wild amphibian populations through hands- on action both locally and internationally. We foster personal relationships between people and nature by providing opportunities for citizens of all ages to become directly involved in global amphibian conservation. Through this involvement, our volunteers become part of a growing and passionate advocacy for the protection and restoration of wild amphibian populations and the environments on which they, and ultimately COVER Rhinoderma darwinni we, depend. Photo by Danté Fenolio THE MAGAZINE OF TREE WALKERS INTERNATIONAL AND AMPHIBIAN CONSERVATION from the director The hellbender (Cryptobranchus alleganiensis) is a species of giant salamander endemic to eastern North America. Larger than any other salamander in its range, it is a habitat specialist, filling a very specific niche within a very specific environment. To survive the hellbender requires a consistently high level of dissolved oxygen found in chronically cold, swift flowing riffles of water. However, due to a variety of factors, its numbers are in dramatic decline throughout much of its range. It is that last fact that makes such a unique creature so common among other amphibians. You have no doubt heard the warnings over the last couple of years: we are in the midst of the 6th Great Extinction. Amphibian populations all over the globe are in decline due to habitat loss and modification, pollution, climate change and the spread of an amphibian- killing fungus, Chytridiomycosis. At one time, illustrations like the one above were the only glimpse people had of creatures like the hellbender. We hope, that through awareness and novel approaches to conservation, that it does not become the only way people will be able to view them in the future. FROM THE EDITOR 1 amphibian health & nutrition The back and head are generally solid black, although in some individuals there is an interrupted yellow median dorsal stripe. A wide gold, red-orange or orange dorsolateral stripe runs from each side of the snout over the eyes and back, down to the base of the thigh. A single white line projects from the shoulder, at the insertion of the upper arm, and runs along the lip to just under the eye. The dorsal surfaces of the limbs show dense blue-green speckling on a black background, while the venter and ventral surfaces of the limbs are The Quality of a Frog BY ED KOWALSKI Every now and then in various discussions there are It has been well established in the literature that size references to “poor quality” frogs, usually referring to at metamorphosis directly affects adult size. Tadpole smaller adult size or less colorful animals as compared growth is directly affected by light, water quality, to either the initial wild caught imports or frogs that temperature and to a lesser extent by the (protein) were directly observed in the wild. There are usually composition of their diet. High protein diets combined two main theories put forth as to the reason for with optimal rearing conditions will not only encourage the disparity between the frogs: nutritional and/or an optimal rate of growth, but should also maximize genetic. In actuality, the difference is probably due size at metamorphosis. Slower growth rates and/or to a convergence of more than one factor, and a basic reduced size at metamorphosis can usually be resolved review and discussion of these issues may help provide when conditions for the tadpole are improved. With a little clarity as well as direction on this topic. This respect to dendrobatids, there have been fads over the article should in no way be considered definitive and years for different tadpole diets (excluding obligate probably should be considered speculative at this time egg feeders) ranging from primarily plant-based diets due to the speed at which the available information is (nettle, spirulina, algae based flake foods) to diets changing. high in animal matter (Tadpole Bites©, black worms, 2 LEAF LITTER • VOL 3 ISSUE 2 fish-based flake foods). The diets utilizing higher in conditions which optimize activity and breeding protein levels should result in maximizing size at periods with little to no seasonal variations to separate metamorphosis, yet adult size of the frogs in captivity breeding from non-breeding periods, this is an area does not appear to have varied significantly. where changes in not only time to maturation but reproductive frequency can significantly impact the Temperatures for rearing tadpoles are often subject growth of the animals in question. In the wild, active to day/night drops as the tadpoles are often reared foraging for food items, food items that are less calorie in ambient room temperatures. These temperatures dense (ants versus crickets, and fruit flies), as well as anecdotally appear to be within the range of what is seasonal limits on reproduction would reduce not only known to occur in the wild, but the fairly constant the rate of reproduction, but reduced fat stores allowing temperatures in captivity should lead to standardized for greater periods of growth. (also see thoughts below conditions for growth and consequently should not on Phenotypic Plasticity.) be a primary cause in the differences seen between wild and captive populations (for a number of One of the potential differences in the size of the anuran species in the literature, lower temperatures frogs may be due to phenotypic plasticity (which is increases size at metamorphosis by increasing time to where an animal demonstrates different phenotypes metamorphosis). in response to environmental conditions) as many of the dendrobatids are housed in conditions that Light can have a significant effect not only on the vary significantly from their natal environment. tadpoles but post metamorphosis. Tadpoles that For example, leaf litter dwelling species are often are deficient in melatonin (such as being kept under maintained in extremely heavily planted enclosures red lights and/or mainly in the dark), then time to which while aesthetically pleasing to the eye provide metamorphosis is reduced with a subsequent loss different environmental conditions than those in the in size at metamorphosis. As a further complication wild. The density of the plantings in these enclosures photoperiods that outside of normal day light (10:14 may actively inhibit the movement of the frogs which day/night to 14:10 day/night) can change not only along with the conditions which optimize reproduction growth but can significantly affect feeding behaviors. may result in differences in size (as larger frogs may In some species, as the ratio of day to night decreased, be at a disadvantage for example in foraging, and feeding decreased as well. This lowered intake will have courtship behaviors. Phenotypic plasticity can affect a direct impact on the size at metamorphosis. a population very quickly with significant difference appearing as quickly as one generation. If phenotypic It is also well known in the literature that the adult plasticity is the component (or one of the components) size of the frog also depends on the size at which of the differences seen between captive and wild reproduction begins to occur as resources are diverted populations then the captive population(s) may be at from growth to reproduction. A number of different risk of losing alleles (genetic variation) via relaxed or factors can affect the size at reproduction of the frog, passive selection for smaller frogs. including but not limited to photoperiod, nutrition, as well as genetics. The rest of the article will touch upon Simple genetic effects may also be a cause in the these topics and their potential effects. differences between the populations of wild and captive frogs. Unless the captive populations are managed in Photoperiod can also change the rate at which the frog a manner that encourages maximal genetic diversity, reaches sexual maturity as well as modifying growth the genetics of the population will shift over time rates of the frog. Day lengths that have a light period potentially fixing one or more undesirable traits like longer than 14 hours can cause frogs to reach sexual smaller size at maturity. Passive and relaxed selections maturity at an earlier age and smaller size. In addition are two more potential reasons for the differences seen differing photoperiods can either increase the rate at in the populations of the frogs. Both of these methods which a frog grows or decrease the rate of growth. It is of genetic selection are similar in their effects and hard to generalize in these cases as there appears to be depending on the size of the population in question a lot of variation not only between species but within may have a very rapid effect on the morphology. As species. a further complication, these changes can eventually result in the captive population being rendered non- It has been established in other animals that the viable (this may be best exemplified by problems time to first reproduction is also partly controlled by seen in larger scale aquaculture requiring a continual nutrition. Given that many frogs in captivity are fed to reacquisition of brood stock) excess resulting abundant fat reserves, are maintained AMPHIBIAN HEALTH & NUTRITION 3 In the end, there are potentially multiple causes that way to changing the metabolic usage of the animal.