Variable reptile responses to introduced predator control in southern Australia

2019 ◽  
Vol 46 (1) ◽  
pp. 64 ◽  
Author(s):  
Yang Hu ◽  
Graeme Gillespie ◽  
Tim S. Jessop
Keyword(s):  
Species Richness ◽  
Fire Regime ◽  
Structural Parameters ◽  
Ecological Niches ◽  
Mesopredator Release ◽  
Pitfall Trapping ◽  
Arboreal Marsupials ◽  
Introduced Predators ◽  
Mammalian Predators ◽  
Body Sizes

Context Australia harbours an immense diversity of reptiles, which are generally expected to have frequent and diverse trophic interactions with introduced mammalian carnivores. Nevertheless, the potential for predatory or competitive interactions is likely to be contingent on multiple processes, including the importance of reptiles in the diet of introduced predators, alongside overlaps in their body sizes and ecological niches that would influence the strength of their interactions. In Australia’s temperate and relatively productive mesic environments there is little understanding of how introduced mammalian predators affect reptile assemblages. Aims The aim was to investigate the effects that a European red fox (Vulpes vulpes; 5–7kg) suppression program had on the abundance and species richness of a reptile community, with species ranging in size from the largest local ectothermic predator, the lace monitor (Varanus varius; 4–7kg), to small terrestrial reptiles (mostly 10–150g). Methods We utilised two sampling designs (baited camera monitoring stations and pitfall trapping) to evaluate the effects of fox suppression and other site-level ecological covariates (fire regime and habitat vegetation characteristics) on the lace monitor and small terrestrial reptiles. Reptile abundance and richness at site level were estimated from count-related abundance models. Key results For lace monitors, significantly higher abundances occurred in poison-baited areas relative to control areas. This suggests that fox suppression can affect the populations of the lace monitor via mesopredator release arising from reduced competition and, possibly, predation. For small terrestrial reptiles, neither abundance nor species richness were influenced by fox suppression. Individual abundances of the three most common small reptile species matched the overall pattern, as only responses to structural parameters of the habitat were detected. Conclusions Fox suppression can have different impacts for different reptile taxa, pending their ecological niche, as only the largest species was affected. Implications Increase in lace monitor abundance may change food web dynamics in fox-suppressed sites, such as by increasing predation pressure on arboreal marsupials.

scholarly journals Rates of ecological divergence and body size evolution are correlated with species diversification in scaly tree ferns

2016 ◽  
Vol 283 (1834) ◽  
pp. 20161098 ◽  
Author(s):  
Santiago Ramírez-Barahona ◽  
Josué Barrera-Redondo ◽  
Luis E. Eguiarte
Keyword(s):  
Species Richness ◽  
Body Size ◽  
Ecological Niche ◽  
Morphological Evolution ◽  
Ecological Niches ◽  
Species Diversification ◽  
Tree Ferns ◽  
Size Evolution ◽  
Body Sizes ◽  
Body Size Evolution

Variation in species richness across regions and between different groups of organisms is a major feature of evolution. Several factors have been proposed to explain these differences, including heterogeneity in the rates of species diversification and the age of clades. It has been frequently assumed that rapid rates of diversification are coupled to high rates of ecological and morphological evolution, leading to a prediction that remains poorly explored for most species: the positive association between ecological niche divergence, morphological evolution and species diversification. We combined a time-calibrated phylogeny with distribution, ecological and body size data for scaly tree ferns (Cyatheaceae) to test whether rates of species diversification are predicted by the rates at which clades have evolved distinct ecological niches and body sizes. We found that rates of species diversification are positively correlated with rates of ecological and morphological evolution, with rapidly diversifying clades also showing rapidly evolving ecological niches and body sizes. Our results show that rapid diversification of scaly tree ferns is associated with the evolution of species with comparable morphologies that diversified into similar, yet distinct, environments. This suggests parallel evolutionary pathways opening in different tropical regions whenever ecological and geographical opportunities arise. Accordingly, rates of ecological niche and body size evolution are relevant to explain the current patterns of species richness in this ‘ancient’ fern lineage across the tropics.

scholarly journals Dinosaurian and mammalian predators compared

Paleobiology ◽  
2002 ◽  
Vol 28 (4) ◽  
pp. 527-543 ◽  
Author(s):  
Blaire Van Valkenburgh ◽  
Ralph E. Molnar
Keyword(s):  
Species Richness ◽  
Large Body ◽  
Sympatric Species ◽  
Size Difference ◽  
Sensory Awareness ◽  
Theropod Dinosaurs ◽  
Top Predators ◽  
Mammalian Predators ◽  
Body Sizes ◽  
Trophic Similarity

Theropod dinosaurs were, and mammalian carnivores are, the top predators within their respective communities. Beyond that, they seem distinct, differing markedly in body form and ancestry. Nevertheless, some of the same processes that shape mammalian predators and their communities likely were important to dinosaurian predators as well. To explore this, we compared the predatory adaptations of theropod dinosaurs and mammalian carnivores, focusing primarily on aspects of their feeding morphology (skulls, jaws, and teeth). We also examined suites of sympatric species (i.e., ecological guilds) of predatory theropods and mammals, emphasizing species richness and the distribution of body sizes within guilds. The morphological comparisons indicate reduced trophic diversity among theropods relative to carnivorans, as most or all theropods with teeth appear to have been hypercarnivorous. There are no clear analogs of felids, canids, and hyaenids among theropods. Interestingly, theropods parallel canids more so than felids in cranial proportions, and all theropods appear to have had weaker jaws than carnivorans. Given the apparent trophic similarity of theropods and their large body sizes, it was surprising to find that species richness of theropod guilds was as great as or exceeded that observed among mammalian carnivore guilds. Separation by body size appears to be slightly greater among sympatric theropods than carnivorans, but the magnitude of size difference between species is not constant in either group. We suggest that, as in modern carnivoran guilds, smaller theropod species might have adapted to the threats posed by much larger species (e.g., tyrannosaurs) by hunting in groups, feeding rapidly, and avoiding encounters whenever possible. This would have favored improved hunting skills and associated adaptations such as agility, speed, intelligence, and increased sensory awareness.

Changes in small native animal populations following control of European rabbits (Oryctolagus cuniculus) by warren ripping in the Australian arid zone

2019 ◽  
Vol 46 (4) ◽  
pp. 343 ◽  
Author(s):  
P. Elsworth ◽  
D. Berman ◽  
M. Brennan
Keyword(s):  
Arid Zone ◽  
Control Program ◽  
Fold Increase ◽  
Food Sources ◽  
Pitfall Trapping ◽  
Animal Populations ◽  
Introduced Predators ◽  
Paired Control ◽  
European Rabbits ◽  
And Control

Context European rabbits have a great impact on native vegetation and small vertebrates in Australia. Rabbits consume vegetation and promote invasive plants and invasive predators, and compete directly and indirectly with native animals suppressing those populations. Aims We explored the changes in small native vertebrates and invertebrates following the removal of rabbits. Methods Warren ripping was undertaken on a property in south-western Queensland at four sites and the results of pitfall trapping were compared with four nearby paired control sites. Invertebrates and small mammals were counted in pitfall traps, and bird surveys were conducted in all treatment and control sites. Key results Following a rabbit-control program, we observed a four-fold increase in the number of dunnarts trapped in treatment plots, whereas no change was observed in control plots. The spring following the rabbit-control program also saw an increase in some lizards in treatment plots. Conclusions The presence of rabbits in arid-zone Australia can suppress native animal populations. Implications Many species of small native mammals and lizards rely on food sources that fluctuate greatly with environmental conditions. The presence of rabbits altering the landscape, supporting introduced predators, reducing vegetation and, therefore, insects, adds increased pressure for insectivorous species. Rabbit control through warren ripping in arid-zone Australia is an effective method to reduce rabbit numbers, and allowed for an increase in small vertebrates in treated areas.

scholarly journals Studies on the arboreal marsupial fauna of eucalypt forests being harvested for woodpulp at Eden, N.S.W. II. Relationship between the fauna density, richness and diversity, and measured variables of the habitat

1983 ◽  
Vol 10 (2) ◽  
pp. 231 ◽  
Author(s):  
L. W. Braithwaite ◽  
M. L. Dudzinski ◽  
J. Turner
Keyword(s):  
Species Richness ◽  
Density Ratio ◽  
Basal Area ◽  
Individual Response ◽  
Explanatory Variables ◽  
Species Richness And Diversity ◽  
Arboreal Marsupials ◽  
Sugar Glider ◽  
Foliage Nutrients ◽  
Habitat Variables

The relationships were examined between measurements of forest habitat (10 explanatory variables: X) and densities of three species of arboreal marsupials (greater glider, feathertail glider and sugar glider); the sum of these three and an additional five species that occurred; species richness and diversity of all eight species present in the area (six response variables: Y). The habitat variables were: landform profile; elapsed time since a severe fire; degree of forest maturity (total basal area of wood); an index of den tree density; ratio of number of regeneration size trees to den trees; floristic diversity; basal area of peppermints; basal area of gums; basal area of eucalypts with a low level of nutrients in their foliage; and an index of potassium concentration in the foliage. The principal component transformation of the X set of variables (PCA) was used as an aid to interpret the individual response of Y to joint intercorrelated explanatory variables X. The regressions of Y on PCA-transformed X explained 76.2% of variation in density for the greater glider, 50.4% for the feathertail glider, 21.1% for the sugar glider, 68.3% for all arboreal marsupials, 49.7% for species richness and 30.1% for species diversity. The weak regressions obtained for densities for the sugar glider were attributed to probable non-measurement of important understorey habitat variables for this species, and those for species richness and diversity, to the presence of a curvilinear rather than linear relationship to foliage nutrients. The gradient in foliage nutrient concentration appears to be the major determinant of the density and species richness and diversity of arboreal marsupials in the Eden forests. Exceptions to the trend seem to occur where the forests include certain xeromorphic eucalypt species that are high in foliage nutrients yet poor in fauna, and, for the feathertail and sugar glider, in those sections of the Eden forests exhibiting fire successional stages and that are usually composed of eucalypts with low nutrient levels in their foliage.

Effects of habitat and introduced mammalian predators on the breeding success of Yellow-eyed Penguins Megadyptes antipodes, South Island, New Zealand

1999 ◽  
Vol 5 (1) ◽  
pp. 16 ◽  
Author(s):  
Hiltrun Ratz ◽  
Brian Murphy
Keyword(s):  
New Zealand ◽  
Breeding Success ◽  
East Coast ◽  
Marked Effect ◽  
Forest Edge ◽  
Introduced Predators ◽  
Mammalian Predators ◽  
Predator Abundance ◽  
Breeding Seasons ◽  
Predator Guild

The endemic Yellow-eyed Penguin Megadyptes antipodes is threatened by habitat loss and introduced predators on mainland New Zealand. Nine colonies in the Catlins (south-east coast of South Island) were studied to measure breeding success, penguin abundance, and predator abundance in three successive breeding seasons (1991/92 to 1993/94). Nest numbers increased in all nine colonies in the three years despite predation (probably by Stoats Mustefa erminea) being the most important cause of breeding failure. Larger colonies with higher breeding success were in small gullies with limited shrubs and bushes rather than in the most intact mature forest colonies hitherto assumed to be optimal habitat for the birds. Penguin nests were concentrated near the forest edge, but predators were not, so the predation risk was not elevated near the forest edge. Fragmentation of the original forest habitat had no observable adverse effect on breeding success. Stoats dominated the predator guild, while Ferrets M. furo and Feral Cats Felis catus were rare. Trapping to kill predators early in the season had no marked effect on subsequent predation losses, but trapping intervention when a predation outbreak occurred curtailed further chick deaths. A simple population model predicts that Yellow-eyed Penguins populations will grow provided the average total chicks loss is less than 43% per season, or at least 0.85 chick per nest fledges each year. This requires predation losses to be less than 34%.

The elevation gradient of lichen species richness in Nepal

2009 ◽  
Vol 42 (1) ◽  
pp. 83-96 ◽  
Author(s):  
Chitra Bahadur BANIYA ◽  
Torstein SOLHØY ◽  
Yngvar GAUSLAA ◽  
Michael W. PALMER
Keyword(s):  
Species Richness ◽  
Endemic Species ◽  
Elevation Gradient ◽  
Distribution Patterns ◽  
Lichen Species ◽  
Ecological Niches ◽  
Published Data ◽  
Elevation Gradients ◽  
Wide Range ◽  
Taxonomic Groups

AbstractThis study of elevation gradients of lichen species richness in Nepal aimed to compare distribution patterns of different life-forms, substratum affinities, photobiont types, and Nepalese endemism. Distribution patterns of lichens were compared with elevational patterns shown by a wide range of taxonomic groups of plants along the Nepalese Himalayan elevational gradient between 200–7400m. We used published data on the elevation records of 525 Nepalese lichen species to interpolate presence between the maximum and minimum recorded elevations, thereby giving estimates of lichen species richness at each 100-m elevational band. The observed patterns were compared with previously published patterns for other taxonomic groups. The total number of lichens as well as the number of endemic species (55 spp.) showed humped relationships with elevation. Their highest richness was observed between 3100–3400 and 4000–4100m, respectively. Almost 33% of the total lichens and 53% of the endemic species occurred above the treeline (>4300m). Non-endemic richness had the same response as the total richness. All growth forms showed a unimodal relationship of richness with elevation, with crustose lichens having a peak at higher elevations (4100–4200m) than fruticose and foliose lichens. Algal and cyanobacterial lichen richness, as well as corticolous lichen richness, all exhibited unimodal patterns, whereas saxicolous and terricolous lichen richness exhibited slightly bimodal relationships with elevation. The highest lichen richness at mid altitudes concurred with the highest diversity of ecological niches in terms of spatial heterogeneity in rainfall, temperature, cloud formation, as well as high phorophyte abundance and diversity implying large variation in bark roughness, moisture retention capacity, and pH. The slightly bimodal distributions of saxicolous and terricolous lichens were depressed at the elevational maximum of corticolous lichens.

Germination response to heat and smoke of 22 Poaceae species from grassy woodlands

2005 ◽  
Vol 53 (5) ◽  
pp. 445 ◽  
Author(s):  
S. Clarke ◽  
K. French
Keyword(s):  
Heat Treatment ◽  
Species Richness ◽  
Exotic Species ◽  
Fire Regime ◽  
Fire Regimes ◽  
Grass Species ◽  
Percentage Germination ◽  
Germination Response ◽  
Eastern Australia ◽  
Smoke Water

Grasses form an important component of grassy woodlands, although their response to fire has been understudied. In this study, fire germination responses of 22 Poaceae species from an endangered grassy-woodland community in eastern Australia were investigated. Seeds of 20 native and two exotic species were subjected to heat (no heat, 40, 80 and 120°C) and smoke treatment (10% dilution smoke water) and the percentage germination was compared. Germination response of species showed no consistent pattern to phylogeny and was highly variable. Germination in six species was unaffected by the application of heat or smoke. In five species, heat, irrespective of smoke application, influenced germination. Smoke, irrespective of heat treatment, influenced six species. For a further six species, the effect of smoke varied with temperature. These results suggest that fire regimes will influence the recruitment of grass species differentially and maintaining regional species richness is likely to require the maintenance of a heterogeneous fire regime across the landscape.

scholarly journals New Zealand Falcon nests suffer lower predation in agricultural habitat than in natural habitat

2013 ◽  
Vol 23 (4) ◽  
pp. 512-519 ◽  
Author(s):  
SARA M. KROSS ◽  
PAUL G. McDONALD ◽  
XIMENA J. NELSON
Keyword(s):  
New Zealand ◽  
Natural Habitat ◽  
Habitat Type ◽  
Oceanic Islands ◽  
Artificial Nests ◽  
Video Footage ◽  
Introduced Predators ◽  
Agricultural Habitat ◽  
Mammalian Predators ◽  
The Hill

SummaryIntroduced mammalian predators have been implicated in the majority of avian extinctions on oceanic islands around the globe. Nowhere is this more apparent than in the decimated New Zealand avifauna, where introduced predators remain the primary threat to virtually all surviving endemic species, including the threatened New Zealand Falcon Falco novaeseelandiae. We used remote videography at falcon nests and conducted an artificial nest experiment to compare the rates of predation and responsible predators of falcons nesting in hills against those nesting in nearby commercial vineyards. Overall, 63% of artificial nests in the hills were predated, compared with 38% in vineyards. Further, artificial eggs were predated faster in the hills than those placed in vineyards. Video footage revealed that the suite of predators visiting real falcon nests was similar to those identified attacking artificial nests. However, predators differed across habitats, with nests in vineyards being predated mainly by hedgehogs Erinaceus europaeus and Australasian Harriers Circus approximans, whereas nests in the hill environments were mainly attacked by stoats Mustela erminea. These results demonstrate the important implications of habitat type on predation pressure associated with introduced predators. These may well prove a fruitful avenue of management if breeding can be fostered in safer areas, as in the case of this threatened falcon.

scholarly journals Local Gazetteers Reveal Contrasting Patterns of Historical Changes between Apex Predators and Mesopredators in Eastern China

2020 ◽  
Author(s):  
Kaijin Hu ◽  
Chunhui Hao
Keyword(s):  
Human Population ◽  
Eastern China ◽  
Apex Predators ◽  
Mesopredator Release ◽  
Historical Changes ◽  
Mammalian Predators ◽  
Presence And Absence

AbstractThis research uses both presence and absence records from local gazetteers innovatively to reconstruct the distribution of 6 kinds of mammalian predators in eastern China from 1723 A.D. to 1949 A.D.. With the human population booming, the distribution of tiger, leopard and bear retreated in varying degrees, but the distribution of wolf, fox and dhole expanded in varying degrees, indicating that eastern China experienced a mesopredator release phenomenon.

Summer phytoplankton 24-hours dynamics in the lake Svetloyar (Nizhny Novgorod region)

2021 ◽  
pp. 25-31
Author(s):  
Ekaterina L. Vodeneeva ◽  
Ekaterina M. Sharagina ◽  
Pavel V. Kulizin ◽  
Natalia A. Startseva ◽  
Daria A. Zhurova ◽  
...  
Keyword(s):  
Species Richness ◽  
Daily Activity ◽  
Structural Parameters ◽  
Heated Layer ◽  
Diatom Algae ◽  
Filamentous Cyanobacteria ◽  
Quantitative Development ◽  
Karst Lake ◽  
Main Components ◽  
Nizhny Novgorod Region

In this research the information of structural parameters of algocenoses (species richness, proportions of leading groups, abundance, biomass) in the photosynthetic zone of a unique karst lake Svetloyar (Nizhny Novgorod region) is provided according to the data for the summer of 2012. During the studied 24-hours period the main components of plankton were coccoid green and diatom algae, colonial and filamentous cyanobacteria, whose daily vertical migration was poorly expressed. The maximum of abundance and biomass of these species were noted at the afternoon (the period from 13:30 to 16:30) and in the most heated layer (0–4 m). Motile algae (mainly from phylum Dinophyta) were characterized with more noticeable daily activity. They were present in the algocenoses only in the daytime and evening hours and moved at night and in the morning below the photosynthetic zone. The daily dynamics of the species richness of algae demonstrated was similar with the indicators of quantitative development, while the number of dominant species remained stable during the day (amounting to 1–4 taxa in the sample).

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