Chemical cues can assist intraspecific communication associated with sexual behavior, territoriality, and home-site philopatry. We tested experimentally the influence of chemical cues on the behavior of male Common Musk Turtles (Sternotherus odoratus). In laboratory-controlled choice boxes, we video recorded the location of turtles moving between two water tanks separated by a raised divider. Water was scented by no turtles, the test turtle, another male, or a female. Based on two-hour trials, we considered turtles that spent > 55% of the time in one water tank as having demonstrated a scent preference. From at least 10 replicates of each of six different treatment combinations, males significantly chose tanks with the scent of a female versus tanks with clean water, the scent of self, or the scent of another male. We propose that the smell produced by a female turtle includes an intraspecific chemical cue that helps males search for potential mates.

Aggregations are a common feature of many species although for most taxa, the mechanisms underlying these aggregations are poorly understood. The Augrabies Flat Lizard (Platysaurus broadleyi) is a sexually dimorphic lizard that experiences intense conflict as a result of sexual selection. In the wild, P. broadleyi share communal crevices and aggregate in the presence of large insect plumes. We experimentally tested whether lizards aggregate as a result of social factors. We also tested whether aggregative behavior differed between the sexes and depends on density. We found no evidence that Augrabies Flat Lizards preferentially group for social reasons in the absence of resources or thermoregulatory benefits. This was true for both sexes and at both densities (two-lizard and four-lizard trials). Although social factors did not promote grouping, males sheltered alone significantly more often than expected by chance, suggesting that males actively avoid one another. Therefore, social factors may work to promote social isolation rather than aggregation, under certain circumstances.

Oviposition site choice, which is one of the most important forms of parental care in oviparous reptiles, has major effects on incubation duration, reproductive success, and offspring phenotype. We determined the thermal characteristics of nest-sites selected by females of the lacertid lizard Psammodromus algirus in laboratory thermal gradients, and we linked results with information on the effects of temperature on incubation times and hatchling phenotypes. Temperatures at oviposition sites (mean ± SD = 26.0 ± 1.9°C) were on average lower and had a lower variance than those at available sites (32.0 ± 6.2°C). The duration of incubation decreased dramatically as temperature increased. In fact, the hatching dates predicted by the temperatures selected in the thermogradients were delayed with respect to the mean emergence dates observed in the field. Such disparity might occur because (1) natural incubation temperatures are variable rather than constant, (2) they are expected to rise later in the season, and (3) temperatures that are too high can severely compromise embryonic survival. In addition, females might select relatively low nest-site temperatures because hatching too early can force juveniles to face limited growth opportunities caused by food shortage in the Mediterranean environments in which they live.

Phylogenetic relationships and systematics of the eight currently recognized species of the genus Bombina were investigated using four mitochondrial gene fragments (16S rRNA, 12S rRNA, ND4-tRNA^LEU, and cytochrome b). We prepared two different concatenated datasets: (A) 12S 16S; and (B) Cytb ND4-tRNA^LEU 12S 16S. Partition-homogeneity tests indicated that these combined datasets were homogeneous, and phylogenetic analyses (Bayesian inference, maximum parsimony, neighbor-joining and maximum likelihood) were performed on them. All phylogenetic analyses based on combined dataset A recover two major clades within the genus Bombina (although one of them was weakly supported): a clade corresponding to the subgenus Bombina; and another clade corresponding to the subgenus Grobina. The hypothesis that Bombina orientalis was the sister group of Bombina maxima is rejected by our results. Our results support the monophyly of the southwest China taxa and the validity of Bombina lichuanensis as an independent species. Considering the low genetic differences among the southwest taxa, and previous morphological and karyological evidence, we suggest that Bombina microdeladigitora and Bombina fortinuptialis might be reassigned as subspecies of B. maxima.

The ecological relationships between two sympatric vipers (Vipera aspis and Vipera ursinii) were studied at a mountainous area in central Italy (Gran Sasso, Abruzzo), between spring 2004 and autumn 2006. The two species differed significantly in their altitudinal distribution: V. ursinii being confined to the higher elevations (above 1650 m elevation), and V. aspis being present from the lowest to the highest altitudes (1200–1900 m). We recorded a wide sector of approximately 250 m elevation (between 1650 and 1900 m elevation) where the two species overlapped. In these areas, the two species exhibited significant difference in microhabitat use and diet composition. Male and female V. aspis were larger (SVL) than male and female V. ursinii. Furthermore, the two species exhibited a significant difference in sexual size dimorphism, with females being larger than males in V. ursinii, whereas no such difference in SVL was observed in V. aspis. However, we did not observe any difference in SVL of male and female vipers when comparing sympatric and allopatric populations. Overall, the potential for competition between these two species appears to be low because of their clearly different realized ecological niches.

Species-abundance distributions often form a log series curve with a few common species and a large proportion of rare species. Niche apportionment and random processes such as dispersal and local extinction are reflected in the structuring of abundance ranks among species within a community. Bottomland hardwood forests of the southern United States have high biotic production because of flood pulses that bring in nutrients. The assemblage of snakes in these environments is diverse both in terms of diet and morphology. In this habitat, the high levels of some resources should be involved in the abundance ranks of the most common species, but other factors (e.g., body size) may be important in the abundance ranks of the less common species. We examined the abundances of snakes in a 2300-ha bottomland deciduous forest in northeastern Texas. Fourteen total species were recorded, but only in one year were all species collected. Three semiaquatic species, Thamnophis proximus, Nerodia erythrogaster, and Agkistrodon piscivorus were the most common. These three species eat fish and amphibians that are concentrated in ephemeral pools, but their foraging methods differ. Several other species had intermediate abundances and a wide variety of diets. Smaller and heavier species did not have lower abundances, and we suggest that, although poor dispersal ability may be involved in the rarity of some species, there are likely several factors involved. We hypothesize that both niche characteristics and random processes are involved in producing the stair-step appearance of the abundance ranks of these snakes.

A new species of the Eleutherodactylus unistrigatus group is described from the area of the lake Los Cóndores, Department of San Martín, Peru, at elevations of 2800–3000 m in the Cordillera Central in northern Peru. The new species differs from the other described species of the genus by having smooth dorsum with large tubercles on the flanks, some of which are longitudinally ovoid or longer than wide, and by having bright red or orange (bright cream in preservative) coloration with transverse black bars on the posterior surface of thighs.

Spotted Salamanders (Ambystoma maculatum) and members of the Blue-Spotted Salamander complex (Ambystoma laterale-jeffersonianum complex) often share terrestrial and wetland habitats, allowing controlled comparison of their life-history strategies. We examined population sizes, sex ratios, breeding frequencies, recruitment rates, and age structures, in sympatric populations of Spotted Salamanders and members of the Blue-Spotted Salamander complex across five years. We saw declines in breeding population size that were larger for Blue-Spotted Salamanders than for Spotted Salamanders (55.2% vs. 33.3%), although members of the Blue-Spotted Salamander complex consistently had larger breeding populations. However, members of the Blue-Spotted Salamander complex also had more highly skewed sex ratios than did Spotted Salamanders (female : male, mean ∼ 23:1 vs. 0.8:1), greater intervals between breeding, lower recruitment (0.9 vs. 5.7 juveniles/female/year), and a younger average age (3.7 vs. 5.2 years). In addition, the sex ratio of Blue-Spotted Salamanders became more skewed over time, with a dramatic reduction in the number of males. Much of our demographic data at this site suggest that the lower reproductive success of Blue-Spotted Salamanders may reduce the relative likelihood of their persistence compared to Spotted Salamanders. However, yearly breeding population sizes, reproductive ages, and lack of juvenile demographic data imply that more study is needed to understand the relative likelihood of persistence for these two groups of pond-breeding amphibians.

Three names have been applied to members of the Carlia novaeguineae complex from New Guinea. All three species have been poorly or erroneously diagnosed, leading to the long-time synonymization of Carlia macfarlani and Carlia curta with C. novaeguineae. Both species were removed from synonymy in 1988 but on the basis of erroneous diagnoses. I show that each of these species is valid and provide diagnoses to distinguish among them. Because of the nomenclatural ambiguity occasioned by loss of the type of C. novaeguineae, the meager original description, and the presence of several morphologically similar species, I designate a neotype for that species. Color pattern is important for distinguishing among species in this complex but fades quickly upon preservation, making identification of museum specimens problematic in many instances. For this reason, members of this complex from outside the southern portion of New Guinea remain unassigned and likely represent one or more new species whose descriptions must await provision of fresh material.

Auditory surveys are being used increasingly to monitor amphibians and assess amphibian declines. Interobserver differences in detected number of species during amphibian call surveys have not been widely studied, yet previous studies have assumed these differences are minimal. We examined inter-observer variation in 269 frog call surveys conducted along 20 standardized routes in central Texas. Two trained observers, listening simultaneously 10 m apart, agreed on number of species calling in 79.4% of 5-min surveys and 78.6% of 30-min surveys. The level of observer agreement varied among species. Observers in the present study were more likely to disagree about the presence of a species when only one or a few frogs called from distant sites. Wind and road noise had no significant effects on interobserver variation. Presence of moonlight was negatively associated with interobserver agreement. Because sampling variation and biases arising from observer effects may lead to inappropriate inferences and misdirected conservation efforts, it is important to control for interobserver differences during the design and analysis phases of research.

Anurans display a variety of antipredator behaviors from flight and crypsis to defensive postures. External attachment of a radio-transmitter is a commonly used technique that could potentially interfere with the antipredator behavior of anurans. We investigated the effect of an externally attached radio-transmitter on the antipredator behavior and vagility of adult Northern Leopard Frogs (Rana pipiens) and adult Wood Frogs (Rana sylvatica). We simulated attacks by birds and snakes and used fluorescent powder to follow the path of individuals through natural habitats. Both species displayed a different frequency of behaviors in response to each predator, but the presence of a transmitter did not affect the frequency of antipredator behaviors. When carrying a transmitter, R. pipiens exhibited a different escape angle during attacks by simulated aerial predators and exhibited a change in the mean turn angle over 4-h movement paths. Rana sylvatica's escape behavior and vagility were unaffected by a transmitter during simulated attacks, although frogs with a transmitter did take more jumps per 4-h movement paths and followed straighter paths than did frogs without a transmitter. The body mass of the individual did not affect any of our behavior or movement metrics. Although most of our metrics did not change markedly in response to the presence of a transmitter, the subtle changes in vagility and escape behavior are analogous to the negative effects of externally attached transmitters seen in birds and mammals. These results suggest that transmitters may have consequences for the energetics, survival, and reproduction of anurans.

Wildlife biologists and managers are concerned about the effects of forest fragmentation and habitat loss on pond-breeding amphibian populations. Most research has assessed the effects of habitat composition at multiple spatial scales on the presence or absence of amphibians at breeding ponds. We were interested in the effects of habitat characteristics on amphibian population size and used Wood Frog (Rana sylvatica) and Spotted Salamander (Ambystoma maculatum) egg mass counts as an index. Between 2001 and 2005, we monitored 65 seasonal ponds within forested landscapes in the Pawcatuck River watershed of Rhode Island. Both species were detected in at least 88% of the ponds sampled. Egg mass counts for both species were highest in ponds that usually dried between early October and late November. Wood Frog egg mass numbers were positively associated with pond hydroperiod, size, and depth; location on glacial fluvial deposits; the extent of persistent nonwoody plant cover in ponds; and the area of upland forest within 1 km of the pond edge. Egg mass numbers were negatively associated with location on alluvium or dense till deposits, percent canopy cover, the number of buildings within 1 km, and the area of residential development within 1 km. Spotted Salamander egg mass counts were positively associated with pond hydroperiod, size, and depth, and upland forest area within 1 km. They were negatively related to location on alluvium. Multivariate models developed from within-pond variables explained more variation in egg mass counts for both species than those developed from landscape-level factors, but the best combined models suggested that habitat characteristics at both scales are useful in the prediction of breeding effort at individual sites. Given the continuing urbanization of southern New England and the ineffectiveness of wetland regulations in protecting required terrestrial habitat around seasonal ponds, proactive techniques also are required to assure the maintenance of pond-breeding amphibian populations.

Knowledge of mating system characteristics can elucidate forces driving sexual selection. In male pitvipers, both male movement tactics and body size are predicted to be important determinants of reproductive success. We used radio telemetry to monitor free-ranging Sistrurus catenatus (Eastern Massasauga) from 2000 through 2002 to determine whether male movement tactics and body size affect mate acquisition. Reproductive behaviors peaked in late July to early August. Females were accompanied by multiple males per season (up to seven); however, male mate acquisition varied considerably with only three of 17 (18%) males located more than one female during a single mating season. During the mating season, male mean daily distance moved (21.8 m) and movement frequency (77%) were higher than during the nonmating season (13.3 m, 63%). Male movement rate and body mass were positively related to the number of females acquired, and heavier males were observed accompanying females as the mating season progressed. Our results indicate that both movement tactics and body size are important in the mating system of S. catenatus; however, direct measures of reproductive success will be necessary before assessing the intensity of sexual selection.

Internal larval oral anatomy was used to explore morphological diversity and its contribution to the systematics of the genera Aplastodiscus, Bokermannohyla, and Hypsiboas, belonging to the tribe Cophomantini. Internal oral morphology was examined for tadpoles of 12 species. All species have a large pair of infralabial papillae on the buccal floor and other papillae on the prelingual region. In Aplastodiscus and Bokermannohyla, the large infralabial papillae have digitiform secondary projections. The number and arrangement of the buccal floor papillae varies among species, but they are more numerous in Aplastodiscus and Bokermannohyla. The arrangement of the postnarial papillae is variable, but in Aplastodiscus and Bokermannohyla, they show a definite, inverted V-shape pattern. The lateral ridge papillae are more complex in larvae of Bokermannohyla with long digitiform secondary projections. Tadpoles of only Aplastodiscus albofrenatus, Aplastodiscus eugenioi, and Bokermannohyla luctuosa have papillae on the buccal roof arena and larvae of all species have lateral roof papillae except Hypsiboas albomarginatus and Hypsiboas cinerascens. Larvae of Aplastodiscus, Bokermannohyla, and Hypsiboas presumably share the presence of vacuities anterior to the internal nares; although this character state is clearly synapomorphic within hylids, it is still uncertain whether it is exclusive of these three genera or whether it is present in the other genera of the tribe Cophomantini (Hyloscirtus and Myersiohyla). The inclusion of internal oral anatomy characters, such as the narial vacuities, in systematic studies is certainly valuable because it will provide additional information toward the understanding of phylogenetic relationships.

Amphibian declines have been documented worldwide; however the vast majority are species associated with aquatic habitats. Information on the status and trends of terrestrial amphibians is almost entirely lacking. Here we use data collected across a 12-yr period (sampling from 1984–86 and from 1993–95) to address the question of whether evidence exists for declines among terrestrial amphibians in northwestern California forests. The majority of amphibians, both species and relative numbers, in these forests are direct-developing salamanders of the family Plethodontidae. We examined amphibian richness and evenness, and the relative abundances of the four most common species of plethodontid salamanders. We examined evidence of differences between years in two ecological provinces (coastal and interior) and across young, mature, and late seral forests and with reference to a moisture gradient from xeric to hydric within late seral forests. We found evidence of declines in species richness across years on late seral mesic stands and in the coastal ecological province, but these differences appeared to be caused by differences in the detection of rarer species, rather than evidence of an overall pattern. We also found differences among specific years in numbers of individuals of the most abundant species, Ensatina eschscholtzii, but these differences also failed to reflect a consistent pattern of declines between the two decadal sample periods. Results showing differences in richness, evenness, and relative abundances along both the seral and moisture continua were consistent with previous research. Overall, we found no compelling evidence of a downward trend in terrestrial plethodontid salamanders. We believe that continued monitoring of terrestrial salamander populations is important to understanding mechanisms of population declines in amphibian species.

Amphibian declines and extinctions are critical concerns of biologists around the world. The estimated current rate of amphibian extinction is known, but how it compares to the background amphibian extinction rate from the fossil record has not been well studied. I compared current amphibian extinction rates with their reported background extinction rates using standard and fuzzy arithmetic. These calculations suggest that the current extinction rate of amphibians could be 211 times the background amphibian extinction rate. If current estimates of amphibian species in imminent danger of extinction are included in these calculations, then the current amphibian extinction rate may range from 25,039–45,474 times the background extinction rate for amphibians. It is difficult to explain this unprecedented and accelerating rate of extinction as a natural phenomenon.

Posthatching yolk in oviparous vertebrates is thought to supply the hatchling with energy for a period of time after hatching in habitats that might require fasting. To examine strategies of posthatching energy use in Apalone mutica, hatchlings were fed or not fed over periods of nine weeks in 2003 and six weeks in 2004. Mass, plastron length, carapace width, and body condition changed during the course of the experiment; all trajectories of change, except carapace width in 2004, differed between fed and unfed hatchlings. Trajectories of fed hatchlings were significantly higher than unfed hatchlings. Fed and unfed hatchlings used internalized yolk at similar rates: 50% of the yolk was depleted by day eight after hatching and 90% by day 27. Metabolic rate (approximately 0.236 ml CO₂ h⁻¹) did not differ between fed and unfed hatchlings. Yolk reserves are insufficient to sustain hatchlings to the first overwintering season, but with access to external forage, hatchlings appear to use yolk reserves to meet maintenance demands to support maximal growth.

Male Brown Anoles (Anolis sagrei) have been found in laboratory studies to court unfamiliar females more intensely than familiar females and in choice tests to preferentially court and mate with unfamiliar females. The objective of the present study was to determine how the intensity of male courtship behavior changes following physical exposure of males to previously unfamiliar females. The courtship behavior of males was recorded in 30-min courtship tests with familiar females (pretest), with unfamiliar females (first test), and with previously unfamiliar females after males had been physically exposed to them for two days (retest). When males were first visually exposed to unfamiliar females in the first test, they courted them significantly more intensely than they had courted familiar females in the pretest. Specifically, males gave more bobbing displays with dewlap extensions and spent more time adjacent to the stimulus female in courtship tests with unfamiliar females than in tests with familiar females. However, when males were housed with previously unfamiliar females for two days and then visually exposed to them in the retest, they did not court them significantly differently than they had courted familiar females. These results suggest that the heightened courtship response of males to unfamiliar females disappears relatively quickly after males have had physical exposure to females.

Geckos are generally nocturnal and show no sexual dichromatism, and males are usually smaller than females. Ptyodactylus guttatus is an unusual gecko. It is active by day and night and is sexually dichromatic, and males are larger than females. We studied P. guttatus at two sites in southern Israel. Eggs were laid between May and October at Haluqim, where we studied eggs in natural caves. At a second site, Hazeva, P. guttatus occur on buildings at a density of 390 ha⁻¹. This is 195 times the density that the species occurs in natural habitats. At Hazeva, adult males inhabited large home ranges, which generally overlapped with one or more smaller home ranges of females. The pattern of home-range overlap presumably reflects the opportunities for mating. A path analysis was consistent with the hypothesis that females spaced themselves to gain access to insects (which they eat) attracted to wall lights on the buildings, and that males space themselves to gain access to female mates. We did not find evidence of territoriality in this population but observed males guarding females. Large male body size may provide priority access to mates, and the distinct male dorsal pattern may have arisen because light does not constrain the use of visual signals in these unusual, largely diurnal geckos, to the same extent as it may in nocturnal geckos.

Introduced American Bullfrogs (Rana catesbeiana) have established breeding populations in several provinces in China since their introduction in 1959. Although Bullfrogs are viewed as a potentially important predator of Chinese native anurans, their impacts in the field are difficult to quantify. We used two experiments to examine factors likely to mediate Bullfrog predation on native anurans. First, we examined effects of Bullfrog size and sex on daily consumption of a common Chinese native (Rana limnocharis). Second, we examined whether Bullfrogs consumed similar proportions of four Chinese natives: Black-Spotted Pond Frog (Rana nigromaculata), Green Pond Frog (Rana plancyi plancyi), Rice Frog (R. limnocharis), and Zhoushan Toad (Bufo bufo gargarizans). We found that larger Rana catesbeiana consumed more R. limnocharis per day than did smaller R. catesbeiana, and that daily consumption of R. limnocharis was positively related to R. catesbeiana body size. When provided with adults of four anurans that differed significantly in body size, R. catesbeiana consumed more individuals of the smallest species (R. limnocharis). However, when provided with similarly sized juveniles of the same four species, R. catesbeiana did not consume any species more than expected by chance. Our results suggest that body size plays an important role in the predatory interactions between R. catesbeiana and Chinese native anurans and that, other things being equal, smaller species and individuals are at greater risk of predation by R. catesbeiana.

Although a highly visible component of the West Indian herpetofauna, few data address the biology of Curly-Tailed Lizards (Leiocephalus). We examined sexual dimorphism in size and head shape and reproductive life-history characteristics for five species of Leiocephalus from the Dominican Republic. Many hypotheses have been posited to explain head shape dimorphism in lizards. Previous studies on Leiocephalus lizards failed to support the niche divergence hypothesis. Consequently, we examined patterns of head shape dimorphism by measuring the scaling relationships of head dimensions of males and females for each species. Head dimensions of the sexes mostly scaled isometrically or with negative allometry, which may support the differential growth hypothesis, although patterns in one species (Leiocephalus semilineatus) suggest that sexual selection may be operative. Clutch sizes varied from 1–4 eggs across species, but mean clutch size generally does not differ significantly among species. Similarly, egg size varies little across species, with only the smallest of the species examined, L. semilineatus, differing significantly from the other species. Therefore, although maximum female snout-vent lengths differ by as much as 50 mm, reproductive characteristics are relatively static. These data are suggestive of an optimal reproductive strategy for Leiocephalus lizards, although detailed experimental data are necessary to examine this fully.

Marginal teeth of iguanine lizards have been studied to some extent, but some aspects of tooth growth remain poorly known. Growth of marginal teeth in Ctenosaura similis is described based on examination of 22 dry skulls. The number of premaxillary teeth remains constant; the number of maxillary and mandibular teeth increases allometrically; and there is no correlation between number of pterygoid teeth and size. Ontogenetic changes in tooth morphology probably are related to ontogenetic shifts in diet. Larger individuals have large fanglike anterior marginal teeth, which might represent an adaptation for consumption of fleshy plant material and occasional carnivory. Other genera of iguanine lizards are primarily herbivorous throughout life; thus, carnivory and the related ontogenetic changes in tooth morphology are derived features within the iguanine clade.

Although there is increasing recognition of the importance of terrestrial habitat to aquatic fauna, little is known about the specific habitat requirements of these species at a fine scale within the terrestrial landscape. Our knowledge of subadult life stages of many species, specifically aquatic turtles, is particularly depauperate. We used radio-telemetry to determine the timing and extent of terrestrial movements of 11 subadult Eastern Mud Turtles, Kinosternon subrubrum, during the winter. We also quantified microhabitat variables (ground cover composition, shrub cover, and canopy cover) of temporary refugia and overwintering sites (hibernacula) of radio-tagged turtles. On average, hibernacula sites were 72 m from the wetland (defined as the water's edge). Turtles remained at hibernacula a mean of 107 days before emerging in the spring. Radio-tagged turtles selected winter hibernacula with a large component of leaf and pine litter and less tree cover than temporary refugia. The leaf litter may provide stable temperature and soil moisture at hibernacula for overwintering turtles, whereas the open canopy may expose turtles to relatively higher temperatures in the spring prior to emergence.

The taxonomic placement of cantils from Veracruz and Hidalgo, Mexico, has remained uncertain based on the small number of samples available from these areas. We examined the scutellation and color pattern of three new specimens of Agkistrodon taylori from northeastern Hidalgo and adjacent Veracruz and compared these results with the morphology of other A. taylori and the single specimen of Agkistrodon bilineatis lemosespinali from the coastal area of central Veracruz. Our results indicate very little morphological deviation from the range of variation previously reported for A. taylori. In addition, the single specimen of A. b. lemosespinali does not appear to represent A. taylori, contrary to a previous report. However, whether or not it deserves formal recognition as a subspecies distinct from other Agkistrodon bilineatus remains questionable. The presence of A. bilineatus along the eastern coast of Mexico in Veracruz provides support for a previous hypothesis of transcontinental dispersal of A. bilineatus.

We report the discovery of a 2n = 30 karyotype race in the Australian diplodactyline gecko Diplodactylus tessellatus. The new chromosome race has four large metacentric pairs and 11 acrocentric pairs, a unique complement among diplodactyline geckos. Three karyotypic races are now known from D. tessellatus. One retains the ancestral Diplodactylus 2n = 38 all-acrocentric karyotype, whereas the 2n = 30 and the 2n = 28 races appear to have been derived from a 2n = 38 karyotype via fusion of four or five pairs of acrocentrics. Diplodactylus tessellatus and its relatives in the Diplodactylus vittatus species complex are now known to possess five different diploid number complements; 2n = 38, 36, 34, 30, and 28, more variation than any other diplodactyline gecko genus or species group for which data are available.