Modeling Anuran Detection and Site Occupancy on North American Amphibian Monitoring Program (NAAMP) Routes in Maryland

Linda A. Weir, J. Andrew Royle, Priya Nanjappa and Robin E. Jung

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Abstract: One of the most fundamental problems in monitoring animal populations is that of imperfect detection. Although imperfect detection can be modeled, studies examining patterns in occurrence often ignore detection and thus fail to properly partition variation in detection from that of occurrence. In this study, we used anuran calling survey data collected on North American Amphibian Monitoring Program routes in eastern Maryland to investigate factors that influence detection probability and site occupancy for 10 anuran species. In 2002, 17 calling survey routes in eastern Maryland were surveyed to collect environmental and species data nine or more times. To analyze these data, we developed models incorporating detection probability and site occupancy. The results suggest that, for more than half of the 10 species, detection probabilities vary most with season (i.e., day-of-year), air temperature, time, and moon illumination, whereas site occupancy may vary by the amount of palustrine forested wetland habitat. Our results suggest anuran calling surveys should document air temperature,  time of night, moon illumination, observer skill, and habitat change over time, as these factors can be important to model-adjusted estimates of site occupancy. Our study represents the first formal modeling effort aimed at developing an analytic assessment framework for NAAMP calling survey data.

Visual Signaling in Anuran Amphibians

Walter Hödl and Adolfo Amézquita

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Chapter 10 of Anuran Communication.

Comparative Effectiveness of Two Trapping Techniques for Surveying the Abundance and Diversity of Reptiles and Amphibians Along Drift Fence Arrays

Chistopher L. Jenkins, Kevin McGarigal and Lloyd R. Gamble

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CONSTRAINTS AND PATTERNS IN THE EVOLUTION OF ANURAN ACOUSTIC COMMUNICATION

Michael J. Ryan

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Chapter 28 of The Evolution of the Amphibian Auditory System

THE EFFECT OF SOCIAL INTERACTIONS ON ANURAN VOCAL BEHAVIOR

Kentwood D. Wells

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Chapter 20 of The Evolution of the Amphibian Auditory System

A FUNCTIONAL ANALYSIS OF THE MATING CALLS OF THE NEOTROPICAL FROG GENERA OF THE LEPTODACTYLUS COMPLEX (AMPHIBIA, LEPTODACTYLIDAE)

Ian R. Straughan and W. Ronald Heyer

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Abstract: Functional characteristics or design features of mating calls for 19 species in the complex are given and analysed for patterns of relationship and convergences due to functional constraints. Two basic ' mating

call patterns can be defined. The first, a quiet, incessant popping produced by exploding a burst of air through the glottis usually with little amplification by secondary structures, is characteristic of riparian species that call resident females over short distances. The second call consists of a single tone burst (note) produced by passing a pulsed stream, of air through the glottis. Often a change in tension of laryngeal musculature produces frequency modulation through the note. In the latter call, resonance in the vocal sacs provides finer frequency tuning and better radiation of the call for attracting females over much longer distances. Patterns of structural similarities in calls are consistent with relationships based on morphology in some instances and apparently contradict morphological evidence in others, indicating that convergence in mating call characters may occur.

Pseudacris regilla

On 12/03/2012, the G1 news portal published an article about a frog, Pacific Tree Frog (Pseudacris regilla), immune disease chytridiomycosis, caused by the chytrid fungus. The information was extracted from a paper by San Francisco Satate University  researchers (California, USA) in the Proceedings of the National Academy of Sciences of the United States of America journal (PNAS).

The chytrid fungus,  causes the disease chytridiomycosis, has the ability to parasitize widely vertebrates. Specifically on the amphibians, the fungus has been considered one of the most likely causes of the decline of world populations, having wiped out more than 200 species of amphibians worldwide.

Pseudacris regilla is a endemic specie to the U.S. and very abundant. Individuals can contract the fungus, but  symptoms do not occur even in individuals with high levels of infection. Because it is abundant and a reservoir of the parasite, Pseudacris regilla may jeopardize the existence of other sympatric species susceptible to the fungus, spreading the deadly disease. The next step for researchers is to understand the biochemical mechanisms which exist in this specie make it immune to the fungus.

A New Miniature Treefrog of the Scinax ruber Clade from the Cerrado of Central Brazil (Anura: Hylidae)

José P. Pombal Jr., Marcos Bilate, Priscilla G. Gambale, Luciana Sognorelli and Rogério P. Bastos

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Abstract: We describe a new species of treefrog of the Scinax ruber clade related to Scinax fuscomarginatus from southwest of the state of Goia´s in central Brazil. The new species is characterized by its small size (snout–vent length of males, 15.9–18.6 mm; females, 18.1–18.7 mm), very slender body, a snout that is strongly acute in lateral view and subelliptical in dorsal view, two lateral broad blackish stripes from the posterior corner of the eye to inguinal region, reduced toe webbing, and advertisement calls that are a single pulsed note with a pulse period of 2–13 ms and a dominant frequency of 2.51–5.95 kHz. Vocalizations of the new species and S. fuscomarginatus, Scinax parkeri, Scinax squalirostris, and Scinax wandae are provided and discussed.

The Tadpole of Physalaemus moreirae (Anura: Leiuperidae)

Diogo B. Provete, Michel V. Garey, Natacha Y. N. Dias and Denise C. Rosa-Feres

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Abstract: We describe the external morphology of the tadpole of the frog Physalaemus moreirae. We also provide a review of internal oral features, chondrocrania, and a characterization of the genus based on larval traits. The internal oral features and the external morphology of P. moreirae are most similar to P. jordanensis, a species allocated to the P. gracilis group. None of the larval traits supports the current intrageneric arrangement of species, because several features are shared by species belonging to different species groups. We argue for the inclusion of larval traits in future phylogenetic studies in order to understand the evolution of larval characters.

Amphibian Conservation in the Caatinga Biome and Semiarid Region of Brazil

Milena Camardelli and Marcelo F. Napoli

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Abstract: The Brazilian Ministry of the Environment (Ministe´ rio Do Meio Ambiente, MMA) proposed defining priority areas for Brazilian biodiversity conservation in 2007, but to date, no definitions of priority areas for amphibian conservation have been developed for the Caatinga biome or the semiarid region of Brazil. In this study, we searched for ‘‘hot spots’’ of amphibians in these two regions and assessed whether the priority areas established by the MMA coincided with those suitable for amphibian conservation. We determined amphibian hot spots by means of three estimates: areas of endemism, areas of high species richness, and areas with species that are threatened, rare, or have very limited distributions. We then assessed the degree of coincidence between amphibian hot spots and the priority areas of the MMA based on the current conservation units. We analyzed areas of endemism with the use of a parsimony analysis of endemicity (PAE) on quadrats. The Caatinga biome and semiarid region showed four and six areas of endemism, respectively, mainly associated with mountainous areas that are covered by isolated forests and positively correlated with species richness. All areas of endemism coincided with one or more priority areas defined by the MMA. We identify 15 priority areas for amphibian conservation in the Caatinga biome and semiarid region, including the creation of new full-protection conservation units.

Strategies Used By Tadpoles to Optimize Buoyancy in Different Habitats

John H. Gee and Sylvie L. Rondeau

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Abstract: We measured gaseous lift and specific gravity of larval anurans at regular intervals during development to assess their importance in determining buoyancy in eight species. Specifically, we examined the hatchling, larval, and metamorphic stages of tadpoles from still waters (Limnodynastes dumerili, Limn. peronii, Lithobates septentrionalis, and Rhinella marina), intermittent streams (Litoria genimaculata and Lito. lesueuri), and torrent sections of rivers (Lito. nannotis and Nyctimystes dayi). Buoyancy levels and the strategies used to attain buoyancy varied at different phases of development and with the environment occupied. Buoyancy increased rapidly during development in hatchlings of Limn. peronii, Lith. septentrionalis, and R. marina due to a reduction in specific gravity. Lungs were inflated in early larval stages of all species except for Lito. nannotis, N. dayi, and R. marina, which inflated their lungs following metamorphosis. Limnodynastes dumerili and Limn. peronii used gaseous lift to maintain near-neutral buoyancy throughout larval and metamorphic stages. Lithobates septentrionalis, Stages 25–29 (first summer), possessed a high level of gaseous lift, but buoyancy declined as lung gas volume decreased in Stages 31–43 (second summer). Rhinella marina did not inflate lungs prior to transformation but achieved an intermediate buoyancy level due to a very low specific gravity. The intermittent-stream species Lito. genimaculata and Lito. lesueuri used gaseous lift to achieve buoyancy levels similar to those of Lith. septentrionalis (Stages 31– 43) and R. marina. The torrent-dwelling species Lito. nannotis and N. dayi were the least buoyant; their lungs were not inflated prior to transformation and their specific gravity was elevated. Both gaseous lift and specific gravity are important factors in determining buoyancy in larval anurans.

How the Cricket Frog Lost Its Spot: The Inducible Defense Hypothesis

Geraldo L. F. Carfagno, J. Maxwell Carithers, Leah J. Mycoff and Richard M. Lehtinen

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Abstract: Prey may use a variety of strategies to avoid predators, including behavioral modification and inducible defenses. For an inducible defense to evolve, one necessary component is that the defense must be costly; if it is not, then the defense should evolve into one that is always expressed (i.e., a constitutive defense). However, costs of inducible defenses have not been well-documented. Using predator exposure experiments in aquatic mesocosms, we demonstrate that dark tail coloration (or lack thereof) in Blanchard’s Cricket Frog (Acris blanchardi) tadpoles is an inducible defense. Specifically, Acris tadpole tail spots in treatments with dragonfly predators (Anax sp.) were significantly larger when compared to treatments with fish predators (Lepomis macrochirus). However, tadpoles in control tanks (with no predators) had tail spots that were not significantly different in area from the Anax treatment. Therefore, this defense is unique among those known because the presence of fish induces the loss (not the appearance) of this morphology. Because Acris tadpoles express the tail spot in the absence of predation risk, this phenotype also does not appear to have any  substantial allocation cost. We also document predation of Acris tadpoles by a fish predator and demonstrate reduction in movement and differential habitat use in the presence of fish predator cues. Under predation risk, tadpoles became less active and occupied the shallowest regions of their habitats. This combination of plastic morphological and behavioral defenses likely allows these frogs to successfully breed in a broad range of aquatic habitats with different assemblages of predators. While likely effective in reducing vulnerability to Anax attacks, the tail spot may increase vulnerability to fish. Our results suggest that the antagonistic effects of predator-specific inducible defenses may represent another type of cost relevant to the conditions under which inducible defenses are expected to evolve.

Factors Affecting Aggression during Nest Guarding in the Eastern Red-Backed Salamander (Plethodon cinereus)

Jan K. Tornick

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Abstract: Defending young against intruders is a potentially risky behavior, and is energetically costly. Yet female eastern red-backed salamanders, Plethodon cinereus, guard their clutches for many weeks and aggressively defend eggs against predators and conspecifics. I examined the effect of clutch age, clutch size, and attendant size on the level of aggression attained during nest defense by staging conspecific invasions of nests of brooding female P. cinereus in the laboratory. I predicted that older and larger clutches would elicit increased aggression from the guarding females, and that larger females would be more aggressive when defending. The females were significantly more aggressive when guarding older clutches (6 wk postoviposition) than younger clutches (4 wk postoviposition). However, there was no difference in aggressive behavior when females guarded large (10-egg) or small (4-egg) clutches. There was also no relationship between body size and level of aggression; females were aggressive regardless of their size. These results suggest that females are able to evaluate the age (or developmental stage) of their eggs and adjust expenditure accordingly, but are not differentially responsive to clutch size.

Dispersal Versus Site Tenacity of Adult and Juvenile Red- Backed Salamanders (Plethodon cinereus)

Brittany H. Ousterhout and Eric B. Liebgold

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Abstract: In many species of amphibians that display territoriality, it is unclear at what life stage and to what extent dispersal occurs. We examined whether differences existed between life stages in dispersal and homing in red-backed salamanders (Plethodon cinereus) in continuous habitat. In a mark–recapture study, we found that juvenile and adult movements between years were not significantly different. The median distances moved by both adults (0.85–0.88 m) and juveniles (1.14–1.22 m) of P. cinereus between years were similar to the diameter of adult home ranges in this area (1.15 m). In a homing experiment, we found that, although the probability of recapture of translocated individuals under their original cover object increased with body size, both adults and juveniles successfully orientated toward their original cover objects when displaced over short distances (1.5 m and 6.25 m), but their orientation was random when displaced long distances (12.5 m and 25 m). Despite the current assumption that juveniles of P. cinereus lack territorial behaviors, our results suggest that regardless of life stage, site tenacity accounts for lack of movements.

Factors Affecting the Timing of Movements to Hibernation Sites by Western Toads (Anaxyrus boreas)

Constance L. Browne and Cynthia A. Paszkowski

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Abstract: Toads in northern climates may spend seven months or more in hibernation; therefore, behavioral decisions related to hibernation are important for survival. We examined factors influencing the timing and nature of movements to hibernation sites by western toads (Anaxyrus boreas, formerly Bufo boreas) at three study areas in north-central Alberta, Canada, with the use of radiotracking. We found that small toads arrived at the general vicinity of their hibernation sites earlier than larger toads. Entry date into hibernation sites was similar for toads of all sizes. Arrival and entry dates were both significantly related to temperature and/or day length. Larger toads moved to hibernation sites later in the year and moved along straighter paths to reach these sites. We propose that larger toads are older individuals that are familiar with their landscape and locations of suitable hibernacula and that they maximize their fitness by remaining at good foraging grounds as late in the year as possible.

Call Trait Variation in Morelett's Tree Frog, Agalychnis moreletii, of Belize

Venetia S. Briggs

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Abstract: Calling behavior and the properties of a male’s call directly affect mate choice and mating success in frogs. In this study, I investigated the difference in call properties within and among males of Agalychnis moreletii at a breeding population in Belize. As a first step toward understanding female preference for specific male advertisement calls, I examined the variation of call traits from 575 calls of 30 individuals. I described and quantified call properties both within and among males and examined the relationship between mating success and body size. All of the call traits that I examined exhibited significantly higher among-male variation than within-male variation. Static call properties such as dominant frequency and call amplitude had the lowest variation within and among males. Dominant frequency was negatively correlated with body size, supporting a body-size constraint for this call trait. Call properties such as call rates, mean pulses per call, and call durations displayed greater variability among males. Such variability in these dynamic call traits suggests energy constraints because calling longer and calling more frequently are energetically costly. As a result, dynamic properties may be indicators of male quality and play a greater role in mate choice. Indeed, males found in amplexus produced a greater number of calls and those calls were of longer durations and tended to have a shorter intercall interval. Here, I characterize call trait variation and document call properties as indicators of  mating success in the process of sexual selection in anuran communication.

You Are What You Eat: Parasite Transfer in Cannibalistic Cane Toads

Lígia Pizzatto and Richard Shine

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Abstract: Pathogen transfer may be an important but poorly understood cost of cannibalism. Does the consumption of smaller conspecifics by Cane Toads (Rhinella marina) result in transfer of viability-reducing parasites such as nematode lungworms (Rhabdias pseudosphaerocephala)? Our experimental trials confirm that cannibalistic toads can indeed become infected, and our results are probably the first evidence of macroparasite transmission via intraspecific predation in amphibians. Our results also show that parasites acquired via cannibalism are viable, develop into fertile adults, and reduce the locomotor performance of the hosts. How cannibalism contributes to nematode transmission and spread in natural populations is not known, but we propose a scenario in which this interaction would be likely to increase the lungworm prevalence, intensity, or persistence.

INTERACTIONS BETWEEN INFECTIVE HELMINTH LARVAE AND THEIR ANURAN HOSTS

Crystal Kelehear, Jonathan K. Webb, Mattias Hagman and Richard Shine

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Abstract: Detailed observations on interactions between parasites and prospective hosts during the infection process can clarify (1) the routes by which parasites enter the host and (2) the ability of prospective hosts to detect, avoid, or resist potential parasites. Such information can clarify determinants of host vulnerability. Infective larvae of the nematode Rhabdias pseudosphaerocephala entered the bodies of their anuran host the Cane Toad (Rhinella marina, formerly Bufo marinus) primarily through the orbit (i.e., by crawling over the surface of the toad’s eye) rather than by burrowing through the skin (believed to be the usual route of infection for rhabditid parasites). In our experimental infections, metamorph Cane Toads detected infective R. pseudosphaerocephala larvae but did not avoid them, nor did they manage to restrict rates of infective larvae penetration by using behavioral means (the toads kicked at infective larvae but failed to dislodge them). Rhabdias pseudosphaerocephala cause damage to their toad host during the process of host entry and throughout the ensuing infection. Despite the high cost of infection and the low cost of avoidance, metamorph Cane Toads seem to lack effective parasite avoidance strategies.

SALT TOXICITY TO TREEFROGS (HYLA CHRYSOSCELIS) DEPENDS ON DEPTH

Emily K. Dobbs, Maria G. Brown, Joel W. Snodgrass and David R. Ownby

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Abstract: Salinization of aquatic habitats is an emerging environmental concern, especially in colder climates where salt is used to prevent road icing during winter months. Salt applied to roads is carried into aquatic environments in storm-water runoff, where fluctuating water levels can result in salt stratification and spatially complex exposure scenarios for embryonic and larval pond-breeding amphibians. We conducted an experiment to investigate the potential interaction between oviposition site selection and toxicity of road salt to embryonic Cope’s Gray Treefrogs (Hyla chrysoscelis). We simulated road-salt stratification in 7-L microcosms containing sediment from a salt-contaminated pond and placed developing eggs at three water depths and directly on the sediment of the microcosms. At the beginning of the experiment, conductivity at the bottom of the microcosms was four to seven (from ~4.0 to 6.5 mS cm-1) times higher than at the top or middle of the water column (~1.0 mS cm-1). Subsequently, survival of eggs placed near the bottom and on the bottom of buckets containing salt-contaminated sediment was near 0%, while survival of eggs at the top and middle depths of the contaminated microcosms, and at all depths in control microcosms, was >60%. After hatching, embryos avoided the bottom of contaminated buckets even though much of the vertical salt gradient had dissipated. In contrast, embryos in control buckets clustered at the bottom. Our results suggest that pond-breeding amphibians that place their eggs away from the bottom may avoid some of the toxic effects of salt contamination, and those that place eggs on the bottom may be at particularly high risk.

Diet and microhabitat use by two Hylodinae species (Anura, Cycloramphidae) living in sympatry and syntopy in a Brazilian Atlantic Rainforest area

Maurício Almeida-Gomes, Fábio H. Hatano, Monique Van Sluys and Carlos F. D. Rocha

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Abstract: We analyzed the diet and microhabitat use for two Hylodinae anurans (Cycloramphidae), Hylodes phyllodes Heyer & Cocroft, 1986 and Crossodactylus gaudichaudii Duméril & Bibron, 1841, living in sympatry at an Atlantic Rainforest area of Ilha Grande, in southeastern Brazil. The two species live syntopically at some rocky streams. The two species differed strongly in microhabitat use. Hylodes phyllodes occurred mainly on rocks, whereas C. gaudichaudii was observed mostly on the water. Regarding diet, coleopterans, hymenopterans (ants), and larvae were the most important prey item consumed by both species. Data suggest that microhabitat use appears to be an important parameter differentiating these frogs with respect to general resource utilization.

NATURAL HISTORY TRAITS OF CROSSODACTYLUS AENEUS (ANURA, LEPTODACTYLIDAE, HYLODINAE) FROM AN ATLANTIC RAINFOREST AREA IN RIO DE JANEIRO STATE, SOUTHEASTERN BRAZIL

Tássia Jordão-Nogueira, Davor Vrcibradic, Jorge A. L. Pontes, Monique Van Sluys and Carlos F. D. Rocha.

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Abstract: There is currently little information on the biology of anurans of the genus Crossodactylus (Leptodactylidae, Hylodinae), which comprise small diurnal frogs that live associated with streams in areas of Atlantic Rainforest. In this study, we analyzed some aspects of the natural history of Crossodactylus aeneus in an area of Atlantic forest in the state of Rio de Janeiro, southeastern Brazil. A total of 37 individuals of C. aeneus were collected during the study, all of them associated with streams inside the forest. Most of the individuals (60%) were found on rocks. Most of the animals were collected during the day, although some were active at night. The diet of C. aeneus was composed of various arthropods, with beetles, ants, dipterans and insect larvae being the predominant items. Of the 21 collected females, eleven contained 70-127 unpigmented vitelogenic eggs.