Distributional changes and population status of amphibians in the eastern Mojave Desert

Several amphibian species historically inhabited sparsely distributed wetlands in the Mojave Desert of western North America, habitats that have been dramatically altered or eliminated as a result of human activities. The population status and distributional changes of amphibians were investigated over a 20,000-km 2 area in the eastern Mojave Desert in 2 ways. For upland sites (i.e., sites outside of major valleys and river floodplains), where wetland habitat is almost exclusively springs, encounter surveys were conducted at 128 sites in 1997-1999, and results were compared to historical (pre-1970) locality records. For lowland sites (i.e., sites within major valleys and river floodplains), locality records and field surveys in 1995-2004 were reviewed to detect changes in distribution over time. Amphibians were found at 79% of upland sites. By far the most common species was the red-spotted toad ( Bufo punctatus , 73% of sites), followed by the Pacific chorus frog ( Pseudacris regilla ), Woodhouse's toad ( B. woodhousii ), relict leopard frog ( Rana onca ), and the introduced American bullfrog ( R. catesbeiana ). Taxa observed or collected in the lowlands since 1990 were Woodhouse's toad, Pacific chorus frog, American bullfrog, and the introduced tiger salamander ( Ambystoma tigrinum ). Four taxa (Vegas Valley leopard frog [ Rana sp.], Arizona toad [ B. microscaphus ], Great Plains toad [ B. cognatus ], and Great Basin spadefoot [ Spea intermontana ]) had historical records but no evidence of occurrence in the study area within the past 5 decades. The amphibian fauna of the study area has changed dramatically in the past century, primarily at lowland sites where habitat loss and modification have been extreme. Striking changes are the nearly complete replacement of native leopard frogs (i.e., Vegas Valley and relict leopard frogs) with the introduced bullfrog, and the complete replacement of the Arizona toad in Las Vegas Valley with Woodhouse's toad or hybrids with predominantly Woodhouse's traits. In contrast, the distributions of 2 species characteristic of upland springs, red-spotted toad and Pacific chorus frog, appear to have changed little from their historical distributions, despite habitat modification at many sites.     

Assortative mating in insects: sexual selection vs. sampling artifact

In this report we analyze patterns of size-assortative mating in an insect genus by (1) describing the consistency and strength of assortative mating among populations of a species and among species of a genus, and (2) determining the role of sampling artifacts in generating this nonrandom pattern of mating. Our data consist of 18 samples of soldier beetles (8 species of the genus Chauliognathus ) from 17 sites within the southwestern United States. Of the 18 samples, just 6 exhibited significant correlations between elytron lengths of mating pairs. We show how these and other significant correlations are generated by 3 kinds of sampling artifacts: mixed-species samples, mixed-population samples, and mixed-microsite samples.     

Non-monogamous mating system and evidence of lekking behaviour in the Helmeted Manakin (Aves: Pipridae)

ABSTRACT

Manakins (Pipridae) are a group of Neotropical birds well known for their spectacular lekking displays and non-monogamous mating system. Nevertheless, the two species of Antilophia have been traditionally considered monogamous and, therefore, an exception to this rule. In this paper, we studied the home range and the mating system of a colour-ringed population of the Helmeted Manakin Antilophia galeata in southeastern Brazil. We propose that it is a non-monogamous species that ranges widely during the breeding season, presenting a lekking behaviour in the form of unspectacular but aggressive chasing courtship displays.     

The scramble competition mating system of the sphecid wasp Palmodes praestans (Kohl)

Males of the wasp Palmodes praestans engage in non‐territorial patrolling behaviour within a scramble competition mating system, showing great fidelity to their wide‐ranging patrolling routes without attempting to monopolize the areas covered. Scramble competition appears adaptive given that mating opportunities are not spatially aggregated in this species, whose females build isolated, single‐celled nests. Because of the female distribution pattern, a male's reproductive success in P. praestans probably depends upon the ability to find highly scattered, unmated females. The females of some close relatives of this sphecid wasp form fairly dense nesting aggregations. As mating system theory predicts, the males of some (but not all) of these species focus their searching at these concentrated nesting/emergence sites where potential mates are clustered spatially.     

Reptiles and amphibians of Idaho, No 2

For about 20 years Richard P. Erwin collected amphibians and reptiles in southwestern Idaho. This report is an attempt to indicate some of his herpetological activities, and to list the numerous individuals, universities, and museums that were recipients of his collections.     

Acoustic ecology of an anuran assemblage in the arid Caatinga of northeastern Brazil

Differences in advertisement calls and calling sites are important mechanisms that regulate interactions in anuran assemblages. Individuals might have preferences for ranges of acoustic parameters and calling sites that reduce overlap and ensure coexistence. Herein, acoustic and ecological data were used to investigate the relationships among 12 anurans that co-occur in temporary ponds in the Caatinga, Cabaceiras municipality, Paraíba state, Brazil. Anurans exhibited calling activity correlated with rainfall, but were also spatially dispersed. High overlap levels in calling microhabitats and acoustic parameters were observed, especially among pairs of closely related species. Analysis of null models showed a lack of structure in the spatial and acoustic niche, indicating the lack of detected competition. Results suggest that the calling activity of the species is strongly influenced by rainfall, moreover, the temporal partition appears to ensure coexistence. Finally, strong historical effects were detected in Leiuperinae, Leptodactylidae and in the partition Hylidae–Leptodactyliformes.     

An austral anuran assemblage in the Neotropics: seasonal occurrence correlated with photoperiod

The study describes habitat use and temporal occurrence of calling males for an austral anuran assemblage in the Neotropics, southern Brazil. Three study sites (S1 – a permanent river and a stream, S2 – a dam and backwater, S3 – two permanent ponds periodically connected) were sampled between August 2005 and July 2006. The site S3 presented the richest and most diverse assemblage and habitat use within studied sites, and was partitioned by species groups. Richness and abundance of calling males for overall assemblage were seasonal, concentrated in spring and summer and correlated with photoperiod. Temperature, rainfall and air humidity were not correlated with the richness and abundance of calling males. Photoperiod also explained the calling seasons when species were analyzed individually. Habitat use and temporal occurrence were complementary in the partitioning of breeding resources, explaining species coexistence.     

Metazoan endoparasites of 18 anuran species from the mesophytic semideciduous Atlantic Forest in southern Brazil

Brazil has the richest anuran biodiversity in the world and many species have not yet been studied for parasites. One hundred and forty frogs belonging to 18 species (Rhinella schneideri, Dendropsophus aff. minutus, Dendropsophus nanus, Hypsiboas albopunctatus, Hypsiboas punctatus, Hypsiboas raniceps, Phyllomedusa tetraploidea, Pseudis platensis, Scinax fuscovarius, Trachycephalus typhonius, Leptodactylus chaquensis, Leptodactylus fuscus, Leptodactylus aff. latrans, Leptodactylus mystacinus, Leptodactylus podicipinus, Physalaemus cuvieri, Physalaemus nattereri and Elachistocleis bicolor) collected in aquatic habitats in forest remnants and surrounding agricultural landscapes in southern Brazil were examined for endoparasites. Twenty-four species of endoparasites were identified among 21 adult and three larval individuals: one species of Monogenea, Polystoma lopezromani; eight species of Digenea, Catadiscus marinholutzi, Catadiscus propinquus, Choledocystus simulans, Gordoderina sp., Neohaematoloechus neivai, Rauschiella lenti, Rauschiella linguatula, Rauschiella repandum; one species of Cestoda, Ophiotaenia sp.; one species of Acanthocephala, Centrorhyncus sp.; 12 species of Nematoda, Aplectana sp., Aplectana travassosi, Cosmocerca podicipinus, Raillietnema sp., Schrankiana formolusa, Falcaustra mascula, Oxyascaris oxyascaris, Ochoterenella digiticauda, Physaloptera sp., Brevimulticecum sp., Rhabdias sp., Parapharyngodon hylidae; and one species of Annelida, Dero (Allodero) lutzi. The endoparasite fauna found is constituted by generalist species. Two new records of occurrence in Brazil and 33 new host records are reported.     

Year-round activity patterns in a hyperdiverse community of rainforest amphibians in Madagascar

Madagascar hosts a high diversity of amphibians estimated at over 500 species, nearly all of them endemic. Surprisingly few data are available on the activity cycles of this fauna, despite its importance for ecological, evolutionary and conservation research. Here we report the results of a year-round survey of amphibians along a transect bordering the Analamazaotra forest near Andasibe in central eastern Madagascar. During 120 transect walks evenly spaced through the year, a total of 2530 individuals of 40 species of anurans was observed. Abundance was higher during the warm/rainy season (December to April) and peaked in February. Of the five climatic predictors measured, only mean temperature and relative humidity showed high importance values, and multi-model averages indicate that these two variables have a strong effect on amphibian abundance along the transect. Species richness showed no evident peak during the study period and was best explained by a model including average temperature and rainfall. Canonical correspondence analysis indicates that Boophis sibilans, B. tephraeomystax, B. boehmei and Plethodontohyla notosticta were more frequently encountered along the transect on cold and humid days while Plethodontohyla mihanika, Gephyromantis boulengeri and Spinomantis aglavei were distinctly more abundant on cold and dry days, and Paradoxophyla palmata on warm and dry days. The results of our study flag a number of species as suitable candidates for future monitoring initiatives and suggest that a simple combination of visual and acoustic surveys can estimate amphibian activity with high sample sizes in Madagascar’s rainforests.     

Occurrence and habitat use of passage neotropical migrants in the Sonoran Desert

Little is known about stopover habitat use by neotropical migratory birds in the deserts of North America. We determined distribution, abundance, and habitat associations of neotropical migrants during spring migration in the Sonoran Desert of southwestern Arizona along large washes that supported xeroriparian scrub vegetation. We detected 91 bird species during surveys, 50 (52%) of which were passage neotropical migrants. Although xeroriparian scrub covered less than 55% of the area surveyed, 97% of all detections of passage migrants were from this vegetation type. By calculating habitat breadth for each species, we classified 87% of passage migrants as xeroriparian specialists. Richness of passage migrants was strongly associated with the presence of overstory (> 2.5 m) mesquite and paloverde. The highest species richness of breeding neotropical migrants was associated with width of the xeroriparian corridor. Habitat characteristics we have shown to be important to neotropical migrants can be preserved and managed by protecting xeroriparian areas, particularly those supporting mature (> 2.5 m) paloverde, mesquite, desert willow, and catclaw acacia trees. Additionally, xeroriparian scrub within the creosote-bursage vegetation type may be particularly important to passage neotropical migrants.     

Breeding movements and reproductive activities of porcupine in the Great Basin Desert

I assessed movements of North American porcupines ( Erethizon dorsatum ) in the Great Basin of northwestern Nevada in relation to reproductive activities during the late summer and fall periods of 1991 and 1992. Porcupines exhibit a mate-defense polygynous mating system and I hypothesized that (1) competitively dominant males would have larger home ranges than both subordinate males and adult females, and (2) variation in home range size among adult male porcupines would be positively correlated with reproductive success. Results indicated that dominant male porcupines ranged over larger areas (average 95% minimum convex polygon home range = 20.7 ha) than subordinate males (average 95% MCP home range = 2.9 ha) and adult females (average 95% MCP home range = 8.2 ha). Analyses of movements in relation to body size and energetic requirements revealed that home ranges of dominant male porcupines were larger than predicted based on body size (approximately 10.2 ha). Breeding period home ranges of dominant male porcupines encompassed portions of the home ranges of 3 to 10 adult females, and indices of reproductive success based on observations of mate-guarding behaviors suggested a strong positive relationship between home range sizes of male porcupines and mating success. Together these data suggested that larger home ranges among dominant males were related to increased mating opportunities and not increased metabolic requirements associated with larger male body sizes. In the study area, however, female porcupines congregated around small, patchily distributed riparian areas, and dominant males with relatively small home ranges encompassing riparian areas may have gained mating access to multiple females. Finally, analyses of overlap among core home ranges (60% MCP) of adult male and adult female porcupines suggested that both sexes maintained relatively exclusive core home range areas, with males exhibiting significantly less range overlap with other males ( ￣x = 9.4%) than females with other females ( ￣x = 27.1%). It is possible that the small, patchily distributed riparian areas in this desertlike area were such a limited resource that females were unable to maintain exclusive use of their home range areas.     

Characteristics of natal and non-natal kit fox dens in the northern Chihuahuan Desert

We studied kit fox den characteristics of the northern McGregor Range of Fort Bliss Military Reservation, New Mexico, during 1994 to 1995. Twenty radio-collared kit foxes used 132 different dens, including 16 natal dens. Kit fox dens were located primarily in creosote-dominated habitat found in relatively flat, well-drained terrain. Natal dens were virtually indistinguishable from non-natal dens; however, natal den entrances were taller than non-natal den entrances. Entrances found at all dens were oriented more frequently toward the northwest and southwest. Kit foxes used more dens during the breeding (January-February) and pup-rearing season (May-July) than during gestation.     

Influence of water size and type on bat captures in the lower Sonoran Desert

We compared bat use by mist-netting at 4 different types of wildlife water developments in southwestern Arizona during summer 2000 and 2001. Scaling our results by netting effort, we caught bats more frequently and observed higher species diversity at tinajas (modified natural rock pools) with larger open-water area compared with ""guzzler"" type water developments that had less open water and more obstacles to bat flight. We caught the fewest bats at guzzlers with buried concrete vault drinkers, which impede bat access and have the smallest areas of open water. Water development designs that minimize evaporative water loss by reducing the amount of open water apparently reduce use by bats in this area.     

Predatory bird populations in the east Mojave Desert, California

We surveyed 7 species of predatory birds weekly during a 12-month period (December 1992 through November 1993) in the east Mojave Desert, California. The Common Raven ( Corvus corax ) was the most frequently observed species with an average of 6.9 sightings per 100 km. Turkey Vultures ( Cathartes aura ), Red-tailed Hawks ( Buteo jamaicensis ), Loggerhead Shrikes ( Lanius ludovicianus ), American Kestrels ( Falco sparverius ), Golden Eagles ( Aquila chrysaetos ), and Prairie Falcons ( Falco mexicanus ) were seen in decreasing order of frequency of observation through the study period. Ravens, Red-tailed Hawks, Loggerhead Shrikes, American Kestrels, and Prairie Falcons were seen throughout the year. Turkey Vultures were not present during winter months, while Golden Eagles were seen only during November and December. Turkey Vultures, Red-tailed Hawks, and ravens were most numerous on agricultural lands, while Loggerhead Shrikes were most common at urban areas. Raven numbers increased with increasing number of linear rights-of-way parallel to the survey route. Perching was the most common behavior type, although Turkey Vultures and ravens were often observed soaring, flying, or standing on the ground near highways. Transmission powerline towers and telephone poles were used as perch sites disproportionately to availability.     

Competition for food and space in a heteromyid community in the Great Basin Desert

A series of removal experiments were performed on Dipodomys merriami, D. microps, and Perognathus longimembris to test for the importance of competition for food and microhabitats in a heteromyid community in the Great Basin Desert. Each of these species was removed singly to determine the short-term effects on the microhabitat preferences of the remaining species. We correctly predicted, based on differences in diet, that the removal of D. microps (a foliovore) would have no effect on D. merriami or P. longimembris (granivores). Using the dominance hierarchy theory, we correctly predicted that removal of a larger heteromyid, D. merriami, would have an effect on the microhabitat use of the smaller P. longimembris, but not vice versa. While our results offer strong evidence of competition for food and microhabitats, the short-term reactions were weak compared to the long-term reactions found in other studies of heteromyids.     

The role of front legs of British corixid bugs in feeding and mating

Summary

The commoner species of British Corixids are found to be predominantly carnivorous, detritus feeders, algal feeders or omnivorous. The adaptations of the front legs to these various types of feeding habits are described. The functional adaptive significance of specific differences in the form of the male front tarsi is also explained.     

Competition Between Adult and Seedling Shrubs of Ambrosia dumosa in the Mojave Desert, Nevada

Seeds of the perennial shrub Ambrosia dumosa germinated in abundance following 11 days of rain during August 1983 at a study site in the northern Mojave Desert. Seedling establishment, growth, and reproduction were observed in natural vegetation and in an area that had been previously cleared of vegetation. For 5,527 A. dumosa seedlings, percent survival in April 1986 averaged 3% in the undisturbed vegetation and 58% in the denuded area. Seedlings occupying the cleared area had grown to sizes up to 0. 1 m 3 m by October 1984; some produced flowers and fruit in the spring of 1985. Surviving seedlings in the undisturbed vegetation were all smaller than 0.001 m 3 and did not reproduce. These pronounced differences in growth, survival, and reproduction associated with the presence or absence of adult shrubs demonstrated an intense competition that is incompatible with indications of mild competition from nearest-neighbor analyses. I therefore hypothesize that competition for water occurred, not by competition for water in two dimensions but by rapid use of a common resource, as if several people were drinking with straws from a common cup. This temporal mechanism would strongly favor adults over seedlings.