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1.
Globally, long‐term research is critical to monitor the responses of tropical species to climate and land cover change at the range scale. Citizen science surveys can reveal the long‐term persistence of poorly known nomadic tropical birds occupying fragmented forest patches. We applied dynamic occupancy models to 13 years (2002–2014) of citizen science‐driven presence/absence data on Cape parrot (Poicephalus robustus), a food nomadic bird endemic to South Africa. We modeled its underlying range dynamics as a function of resource distribution, and change in climate and land cover through the estimation of colonization and extinction patterns. The range occupancy of Cape parrot changed little over time (ψ = 0.75–0.83) because extinction was balanced by recolonization. Yet, there was considerable regional variability in occupancy and detection probability increased over the years. Colonizations increased with warmer temperature and area of orchards, thus explaining their range shifts southeastwards in recent years. Although colonizations were higher in the presence of nests and yellowwood trees (Afrocarpus and Podocarpus spp.), the extinctions in small forest patches (≤227 ha) and during low precipitation (≤41 mm) are attributed to resource constraints and unsuitable climatic conditions. Loss of indigenous forest cover and artificial lake/water bodies increased extinction probabilities of Cape parrot. The land use matrix (fruit farms, gardens, and cultivations) surrounding forest patches provides alternative food sources, thereby facilitating spatiotemporal colonization and extinction in the human‐modified matrix. Our models show that Cape parrots are vulnerable to extreme climatic conditions such as drought which is predicted to increase under climate change. Therefore, management of optimum sized high‐quality forest patches is essential for long‐term survival of Cape parrot populations. Our novel application of dynamic occupancy models to long‐term citizen science monitoring data unfolds the complex relationships between the environmental dynamics and range fluctuations of this food nomadic species.  相似文献   

2.
We identified species‐ and community‐level dietary characteristics for a species‐rich Amazonian parrot assemblage to determine relationships among dietary metrics and use of geophagy sites. Previous studies suggest that soil is consumed at geophagy sites in this region mainly to supplement dietary sodium. We accumulated 1400 feeding records for 16 parrot species over 2 yr and found that seeds, flowers, and fruit pulp featured prominently in diets, while bark, insects, and lichen were consumed in small quantities. Food availability across 1819 trees was measured, and we found that flower availability was highest in the dry season and fruit production peaked in the wet season, but that phenology patterns of the 20 most commonly foraged plant species suggest no serious food bottlenecks. Partitioning of available food resources among the 13 most commonly encountered parrots is suggested by an ordination analysis (DCA), which placed the large macaws (Ara) with the Amazona parrots at the ‘primary forest’ end of a dietary resource axis and four smaller species at the ‘successional forest’ end of the axis. Parrot species associated with successional forest also consumed less plant species overall. Furthermore, these parrot species consuming successional forest resources had higher claylick visitation rates than those consuming primary forest resources suggesting they derive the greatest benefits from soil consumption.  相似文献   

3.
Habitat corridors that facilitate functional connectivity are a fundamental component of wildlife conservation in fragmented landscapes. However, the landscape matrix separating suitable habitat is not uniformly impermeable to movement and management to increase matrix permeability could be an alternative means to maintain connectivity. Gliding mammals are particularly sensitive to fragmentation because their movements are constrained by glide distance thresholds. Populations of gliders in cities are at risk of being isolated by increasing habitat loss and urban development, yet little is known about how the urban matrix affects glider movement. Here we investigate how the level of urbanization and tree cover in the matrix influence matrix permeability to sugar gliders (Petaurus breviceps) within suburban forest reserves. Twenty‐two sugar gliders were radio‐tracked over winter and summer at four reserves. Boundary crossing behaviour was measured as the number of times each glider crossed into the matrix, and matrix permeability was determined as the maximum distance travelled by gliders into the matrix. The majority of gliders (81%) were located in the matrix at least once, and rates of boundary crossing were consistent across urbanization and tree cover levels. Matrix permeability was negatively affected by matrix urbanization, but not by matrix tree cover, and no interaction effects were found. Although distances travelled by gliders into the matrix did not exceed 180 m, they were comparable with typical movement distances by gliders in reserves. Our results demonstrate that the urban matrix can provide suitable habitat for gliding mammals to move and forage, but that increased urbanization may inhibit glider use of the matrix irrespective of tree cover. This finding has implications for conservation planning and suggests that structurally connected areas may not be used if movement behaviour is inhibited. Conversely, management of matrix permeability could be used to maintain connectivity without needing to construct physical corridors.  相似文献   

4.

Aim

Range expansions facilitated by humans or in response to local biotic or abiotic stressors provide the opportunity for species to occupy novel environments. Classifying the status of newly expanded populations can be difficult, particularly when the timing and nature of the range expansion are unclear. Should native species in new habitats be considered invasive pests or actively conserved? Here, we present an analytical framework applied to an Australian marsupial, the sugar glider (Petaurus breviceps), a species that preys upon on an endangered parrot in Tasmania, and whose provenance was uncertain.

Location

Tasmania, Australia.

Methods

We conducted an extensive search of historical records for sugar glider occurrences in Tasmania. Source material included museum collection data, early European expedition logs, community observation records, and peer‐reviewed and grey literature. To determine the provenance of the Tasmanian population, we sequenced two mitochondrial genes and one nuclear gene in Tasmanian animals (n = 27) and in individuals across the species' native range. We then estimated divergence times between Tasmania and southern Australian populations using phylogenetic and Bayesian analyses.

Results

We found no historical evidence of sugar gliders occurring in Tasmania prior to 1835. All Tasmanian individuals (n = 27) were genetically identical at the three genes surveyed here with those individuals being 0.125% divergent from individuals from a population in Victoria. Bayesian analysis of divergence between Tasmanian individuals and southern Australian individuals suggested a recent introduction of sugar gliders into Tasmania from southern Australia.

Main conclusions

Molecular and historical data demonstrate that Tasmanian sugar gliders are a recent, post‐European, anthropogenic introduction from mainland Victoria. This result has implications for the management of the species in relation to their impact on an endangered parrot. The analytical framework outlined here can assist environmental managers with the complex task of assessing the status of recently expanded or introduced native species.
  相似文献   

5.
We estimated densities of parrot and hornbill species in primary and selectively logged forest and forest gardens at two lowland sites on New Britain, PNG. We related differences in abundance to food and nest-site availability in the different habitats and determined whether nest-site availability might limit local breeding populations. Blue-eyed Cockatoo Cacatua ophthalmica and Blyth's Hornbill Rhyticeros plicatus were usually rarer in forest gardens than in primary forest, but both fared well in logged forest. Eclectus Parrot Eclectus roratus was more common in all human-altered forests than in primary forest, and Eastern Black-capped Lory Lorius hypoinochrous was reasonably common throughout but extremely abundant in forest gardens at one site. Parrots and hornbills were recorded eating fruits of 15 tree species and flowers of nine species. Densities of these fruiting and flowering trees were highest in logged forest and forest gardens, respectively, indicating the importance of these anthropogenic habitats as feeding grounds for the assemblage. Active nest cavities were found in large individuals of 12 tree species. Densities of potential nest cavities were highest in primary forest and lowest in forest gardens. At both sites, estimates of potential nest-site density were significantly lower than estimates of the density of pairs of all species of parrots and hornbills: there may be 10–20 parrot/hornbill individuals per nest-hole. Continuing forest alteration, whilst further reducing nest-site availability, may allow large populations of parrots and hornbills to persist due to increased availability of food in some anthropogenic habitats. However, current abundance of such bird species may be a poor correlate of future extinction risk as long-lived taxa may remain common for some period even when annual recruitment has declined to critically low levels.  相似文献   

6.
Apex predators are integral parts of every ecosystem, having top‐down roles in food web maintenance. Understanding the environmental and habitat characteristics associated with predator occurrence is paramount to conservation efforts. However, detecting top order predators can be difficult due to small population sizes and cryptic behaviour. The endangered Tasmanian masked owl (Tyto novaehollandiae castanops) is a nocturnal predator with a distribution understood to be associated with high mature forest cover at broad scales. With the aim to gather monitoring data to inform future conservation effort, we trialled an occupancy survey design to model masked owl occurrence across ~800 km2 in the Tasmanian Southern Forests. We conducted 662 visits to assess masked owl occupancy at 160 sites during July–September 2018. Masked owl site occupancy was 12%, and estimated detectability was 0.26 (±0.06 SE). Cumulative detection probability of masked owls over four visits was 0.7. Occupancy modelling suggested owls were more likely to be detected when mean prey count was higher. However, low detection rates hindered the development of confident occupancy predictions. To inform effective conservation of the endangered Tasmanian masked owl, there is a need to develop novel survey techniques that better account for the ecology of this rare, wide‐ranging and cryptic predator. We discuss the potential to combine novel census approaches that exploit different aspects of masked owl ecology to obtain more robust and detailed data.  相似文献   

7.
Populations of Psittacidae are endangered by habitat loss and the international pet market. The grey parrot (Psittacus erithacus) is among the most traded species, yet little is known about densities and their variability in time and space. The population of grey parrots on the island of Príncipe (Gulf of Guinea) was estimated with distance sampling, in both pre‐ and postbreeding seasons. Abundance was related to a range of habitat features using generalized additive models. Densities averaged 48 ± 3 (SE) individuals km?2 in the prebreeding and 59 ± 4 in the postbreeding season, both extremely high compared to elsewhere in Africa and to other parrot species. Despite a population of 6000–8000 individuals over only 139 km2, parrots were patchily distributed, being unrecorded in ~25% of surveyed areas. Abundance varied seasonally, with densities being significantly higher in secondary compared to primary forest in the post‐ but not in the prebreeding season. Abundance was most tied to the presence of nest‐tree species prior to breeding and to feeding‐tree species and lightly sloping ground after breeding. These results highlight the need to preserve a matrix of habitat types to provide resources for parrots across seasons and ensure that surveys recognize seasonality in habitat use as a potential bias.  相似文献   

8.
Urban landscapes often expose wildlife populations to enhanced edge effects where the biotic and abiotic attributes of native ecosystems have been significantly altered. While some species may respond favourably to edges, there are likely to be varying negative consequences for many forest‐dependent species. In particular, marsupial gliders are influenced by changes in forest composition and structure near edges due to highly specific feeding and nesting requirements, and a high reliance on tree cover to traverse a landscape. We addressed this problem using the squirrel glider (Petaurus norfolcensis) in the fragmented urban landscape of southeast Queensland, Australia. Analysis of variance was applied to determine differences in habitat resources and structure in relation to glider presence and trap success rates in forest fragment interiors compared with road (minor & major) and residential edge habitats. We postulate that an increased presence of squirrel gliders in sites adjacent to minor road and residential edges may be due to the availability of additional resources and/or varying dispersal opportunities. Conversely, forest fragment interiors contain a higher abundance of nest hollows and large trees, together with a greater floristic species richness providing more reliable seasonal foraging sources, which may explain the greater trap success rates of squirrel gliders in these sites. We conclude that while forest fragment interiors provide habitat suitable for year‐round use by greater numbers of squirrel gliders, the conservation value of some edge habitats that provide additional resources and dispersal opportunities should not be underestimated for forest‐dependent mammals; however, each edge type must be assessed individually.  相似文献   

9.
Melopsittacus undulatus is a companion parrot worldwide diffused. Many parrots are considered endangered or vulnerable. The preservation of semen is crucial in endangered species, thus, M. undulatus could be a good model to study sperm characteristics and semen cryopreservation in these other endangered parrots. In this study the effect of the breeding management (males bred in promiscuous aviary or in couple) on sperm characteristics (motility, membrane integrity and morphometry) of fresh and cryopreserved semen was evaluated. The computer-assisted sperm analysis (CASA) revealed a significant effect of the husbandry method on semen characteristics in budgerigars: male housed in couple with the female in individual cages allowed the higher results in term of both semen quantity and sperm quality. Total and progressive motility were significantly higher in males bred in couple (68.7 ± 8.9% and 54 ± 15.9%, respectively) than in promiscuous aviary (48.3 ± 15.1% and 24.4 ± 12.4%, respectively), such as sperm velocity (average path velocity, straight line velocity, and curvilinear velocity). The type of sperm movement (amplitude of lateral head displacement, beat cross frequency, straightness, and linearity), sperm membrane integrity and morphometry parameters seemed not affected by the husbandry method. The standardization of a CASA procedure for the semen analysis in M. undulatus allow further studies on parrot semen manipulation and cryopreservation, but the method used for the breeding of the male could have a significant effect on the semen quality.  相似文献   

10.
Stuart J. Marsden  Kay Royle 《Ibis》2015,157(2):219-229
Estimates of population density and abundance change (differences in density or encounter rates across land uses or time periods) form the cornerstone of much of our knowledge of species' responses to environmental conditions, extinction risks and potential conservation actions. Gathering baseline data on abundance of the world's c. 10 000 bird species and monitoring trends in the light of rapidly changing environmental and harvest pressures is a daunting prospect. With this in mind, we review literature on population densities and abundance changes across habitats in one of the world's largest and most threatened bird families, the parrots (Psittaciformes), to identify gaps in knowledge, model phylogenetic and other influences on abundance, and seek patterns that might guide thinking for data‐deficient taxa and situations. Density estimates were found for only 25% of 356 parrot species. Abundance change data were similarly limited and most came from logged forest, with very few comparisons across different anthropogenic habitats. Threatened species were no more likely to have a density estimate than non‐threatened species, and were less likely to have estimates of abundance change. Exploratory generalized linear mixed models indicated that densities are most influenced by genus, and are generally higher within protected areas than outside. It is unclear whether the latter effect stems from habitat protection, a reduction in poaching or both, but protected areas appear to be beneficial for parrots. Individual members of the ‘parakeet’ genera (e.g. Pyrrhura and Eos) were predictably abundant, whereas within larger‐bodied genera such as Ara (macaws), species were predictably uncommon (< 10 individuals per km2) and there was a long tail of extreme rarity. Responses of parrots to habitat change were highly variable, with natural variation in parrot abundance across different primary forests as great as that between primary forest and human‐altered forests. The speed at which environmental change is affecting the world's parrots far outstrips that of our current capacity to track their abundance and we assess the likely scale of data deficiency in this and other bird groups. Developments in survey and analysis methods such as variants of distance sampling and the integration of niche modelling with point density estimation may increase our effectiveness in monitoring parrots and other important and threatened bird groups.  相似文献   

11.
Herbivorous animals face shortages of different minerals in different geographic areas. In the Amazon Basin, sodium is often limiting, driving herbivores to seek supplemental sources. In the lowlands of the western Amazon Basin, parrots commonly consume sodium‐rich soils at clay licks but lick use varies widely among species, and to date, parrots in the region have not been reported consuming other supplemental sodium sources. We document 11 species of psittacines consuming sodium‐rich leaves and trunks of Attalea butyracea palms growing on sodium‐rich soils in lowland Peru. Consumed palms had more sodium and less potassium than uneaten A. butyracea palms and other palm species in the area. Among A. butyracea palm parts, sodium and Na:K ratios were highest in trunks (consumed by parrots in 94% of the 387 foraging bouts recorded) and lowest in leaves (consumed in only 14% of foraging bouts). The low potassium and high Na:K ratio suggest that birds may be seeking not just any sodium sources, but those low in potassium, as potassium is known to exacerbate dietary sodium shortages. Use of the palms and species’ abundance in the study area were not correlated. Instead, parrot species that consumed palms the most were those that use relatively few traditional soil clay licks. This finding suggests that parrot species in the region have fundamental differences in preferred strategies for obtaining supplemental sodium and may help explain documented interspecific differences in geophagy.  相似文献   

12.
Ongoing habitat loss and fragmentation is considered a threat to biodiversity as it can create small, isolated populations that are at increased risk of extinction. Tree‐dependent species are predicted to be highly sensitive to forest and woodland loss and fragmentation, but few studies have tested the influence of different types of landscape matrix on gene flow and population structure of arboreal species. Here, we examine the effects of landscape matrix on population structure of the sugar glider (Petaurus breviceps) in a fragmented landscape in southeastern South Australia. We collected 250 individuals across 12 native Eucalyptus forest remnants surrounded by cleared agricultural land or exotic Pinus radiata plantations and a large continuous eucalypt forest. Fifteen microsatellite loci were genotyped and analyzed to infer levels of population differentiation and dispersal. Genetic differentiation among most forest patches was evident. We found evidence for female philopatry and restricted dispersal distances for females relative to males, suggesting there is male‐biased dispersal. Among the environmental variables, spatial variables including geographic location, minimum distance to neighboring patch, and degree of isolation were the most important in explaining genetic variation. The permeability of a cleared agricultural matrix to dispersing gliders was significantly higher than that of a pine matrix, with the gliders dispersing shorter distances across the latter. Our results added to previous findings for other species of restricted dispersal and connectivity due to habitat fragmentation in the same region, providing valuable information for the development of strategies to improve the connectivity of populations in the future.  相似文献   

13.
Parrot populations are being increasingly pressured to occupy modified or fragmented landscapes, yet little is known of the habitat requirements of most species, particularly with regard to the effects on breeding habitat. We evaluated nesting habitat of the lilac-crowned parrot Amazona finschi in the modified landscape of coastal Michoacan in Mexico. We located 90 parrot nests in 12 tree species in Michoacan, with lilac-crowned parrots presenting a narrow niche-breadth of tree species used for nesting. Considering an additional 82 nest trees recorded for lilac-crowned parrots in Jalisco, we determined a 51 percent similarity in cavity resource use by parrots in the two dry forest regions. Overall, the predominant nest tree species with 76 percent of nests were Astronium graveolens , Piranhea mexicana , Brosimum alicastrum , and Tabebuia spp., all characteristic of semi-deciduous forest. Only 8 percent of nests occurred in trees characteristic of deciduous forest. Parrots utilized large trees with canopy level cavities as nest sites, and preferred conserved semi-deciduous forest for nesting, with fewer nests than expected in deciduous forest and transformed agricultural land. Nest areas in semi-deciduous forest occurred on significantly steeper terrain, as remnant semi-deciduous forest is restricted to steep ridges and canyons. Those parrot nests in modified habitats and forest patches were located near to continuous forest, with nest trees in open agricultural land being significantly closer to continuous forest than nests in disturbed forest patches. These results demonstrate the importance of conserved semi-deciduous forest as breeding habitat for the threatened, endemic lilac-crowned parrot, making wild populations of the species vulnerable to the high rate of transformation and fragmentation of tropical dry forest.  相似文献   

14.
Although examples are rare, conflicts between species of conservation concern can result from habitat restoration that modifies habitat to benefit a single taxon. A forest restoration program designed to enhance habitat for endangered red‐cockaded woodpeckers (Picoides borealis) may be reducing available habitat for the eastern spotted skunk (Spilogale putorius), a forest‐adapted sympatric species of conservation concern that occurs in the Ouachita National Forest, Arkansas, U.S.A. At small scales, eastern spotted skunks select early successional forest with structural diversity, whereas red‐cockaded woodpeckers prefer mature pine (Pinus spp.) habitat. We surveyed for eastern spotted skunks at 50 managed forest stands, modeled occupancy as a function of landscape‐level habitat factors to examine how features of restoration practices influenced occurrence, and compared known occupied forest stands to those where active red‐cockaded woodpecker nesting clusters were located. The most‐supported occupancy models contained forest stand age (negatively associated) and size (positively associated); suggesting eastern spotted skunks primarily occupy large patches of habitat with dense understory and overhead cover. Red‐cockaded woodpecker nesting clusters were located in smaller and older forest stands. These results suggest that increased overhead cover, which can reduce risk of avian predation, enhances occupancy by small forest carnivores such as eastern spotted skunks. Management activities that increase forest stand rotation length reduce the availability of young dense forest. The practice may enhance the value of habitat for red‐cockaded woodpeckers, but may reduce the occurrence of eastern spotted skunks. Implementing plans that consider critical habitat and extinction risks for multiple species may reduce such conservation conflict.  相似文献   

15.
Africanized honey bees (Apis mellifera scutellata) compete with endangered parrots for nest boxes and can hamper conservation efforts. We tested an integrated pest management push‐pull protocol in the Atlantic Forest in São Paulo, Brazil, in an effort to prevent bee swarms from colonizing nest boxes (N = 30 in the forest plus five in aviaries) meant for use by Vinaceous‐breasted Amazons (Amazona vinacea). Fifteen parrot nest boxes were treated with a permethrin insecticide to “push” scout bees away and each parrot box was paired with a bee trap box containing a pheromone lure to “pull” bees. Over a 1‐yr period (March 2013 to March 2014), 29 insect colonies moved into 18 of the 35 trap boxes. Nine Africanized honey bee, three native Jatai bee (Tetragonisca sp.), and 17 wasp colonies occupied trap boxes. Only one experimental push‐pull pair untreated parrot box was invaded by bees and no parrot boxes in aviaries were colonized. Four of the parrot nest boxes were occupied by birds during our study. Although none were used by Vinaceous‐breasted Amazons, Southern House Wrens (Troglodytes musculus), Green‐winged Saltators (Saltator similis), and Plain Parakeets (Brotogeris tirica) nested in the boxes and all nests were successful. Although long‐term studies are needed before drawing conclusions about the effectiveness of trap boxes, our results suggest that a push‐pull protocol may prove useful for reducing the use of nest boxes meant for parrots and other cavity‐nesting birds by Africanized honey bees and other insects.  相似文献   

16.
Tropical forest degradation is a global environmental issue. In degraded forests, seedling recruitment of canopy trees is vital for forest regeneration and recovery. We investigated how selective logging, a pervasive driver of tropical forest degradation, impacts canopy tree seedling recruitment, focusing on an endemic dipterocarp Dryobalanops lanceolata in Sabah, Borneo. During a mast‐fruiting event in intensively logged and nearby unlogged forest, we examined four stages of the seedling recruitment process: seed production, seed predation, and negative density‐dependent germination and seedling survival. Our results suggest that each stage of the seedling recruitment process is altered in logged forest. The seed crop of D. lanceolata trees in logged forest was one‐third smaller than that produced by trees in unlogged forest. The functional role of vertebrates in seed predation increased in logged forest while that of non‐vertebrates declined. Seeds in logged forest were less likely to germinate than those in unlogged forest. Germination increased with local‐scale conspecific seed density in unlogged forest, but seedling survival tended to decline. However, both germination and seedling survival increased with local‐scale conspecific seed density in logged forest. Notably, seed crop size, germination, and seedling survival tended to increase for larger trees in both unlogged and logged forests, suggesting that sustainable timber extraction and silvicultural practices designed to minimize damage to the residual stand are important to prevent seedling recruitment failure. Overall, these impacts sustained by several aspects of seedling recruitment in a mast‐fruiting year suggest that intensive selective logging may affect long‐term population dynamics of D. lanceolata. It is necessary to establish if other dipterocarp species, many of which are threatened by the timber trade, are similarly affected in tropical forests degraded by intensive selective logging.  相似文献   

17.
This study describes 12 microsatellite loci identified in the African grey parrot Psittacus erithacus. Eleven were polymorphic, with observed heterozygosities 42–94% (average 68) and exclusion powers of PE1 = 0.996 and PE2 = 0.999. Microsatellites have previously been developed for a number of other parrots but showed limited cross‐species polymorphism. Here high levels of cross‐species amplification were observed: 71% of 32 Psittacines (22 genera). At least seven loci, 58%, were polymorphic in other African parrots as well as Neotropical and Australasian parrots, which diverged from the African parrots c30.6 and over 41.4 million years ago, respectively.  相似文献   

18.
Co-operation between two or more individuals has been shown to yield benefits in some vertebrate species (Bygott, Bertram & Hanby, 1979; Packer & Pusey, 1982; Grinnell, Packer & Pusey, 1995), however, until now such behaviour has not been described for marsupials. In this two-and-a-half-year study co-operative behaviour among male sugar gliders ( Petaurus breviceps ) was revealed. A dominant relationship to females was not observed.
Male sugar gliders not only showed extensive co-operative behaviour in suppressing subordinate males, but in sharing food and nesting boxes as well as taking care of the offspring. DNA fingerprinting has been used to describe the genetic variability in relatedness of the coalition partners.
Co-operative behaviour in male sugar gliders was exclusively observed among closely related individuals, therefore supporting the kin-selection theory in this small marsupial.
We describe the genetic variability in relatedness, the behaviour and some physiological parameters of male sugar gliders in four captive groups to test the hypothesis that the sugar glider is an example of co-operative behaviour involving kin selection in marsupials  相似文献   

19.
The ground parrot (Pezoporus wallicus) has a coastal distribution in Victoria and has declined in range since European colonization. Its habitat consists of two major vegetation communities: coastal heathland and sedgeland. These are further divided into various sub-communities. These habitats contained high densities of cyperaceous and restionaceous plants, the seeds of which form the bulk of the bird's diet. Seeds and small fruits of some dicotyledonous plants and grasses are also eaten. Seed production by sedges remains fairly constant over time in sedgelands but varies in heathland, depending on time since burning. This variation is reflected by parallel changes in ground parrot population density. Both long unburnt and very frequently burnt heathlands are unsuitable for ground parrots. The birds also require dense vegetation cover. Ground parrots appear to live in territorial breeding pairs with enforced natal dispersal. This is an adaptation to an environment where habitat is patchily distributed in space and variable in quality over time.  相似文献   

20.
We aimed to estimate the density, occupancy and detectability of Salvator merianae (Tegu) in one of the largest Atlantic rainforest remnants in Espírito Santo, Brazil, the VNR. Species patch occupancy was modelled and used to predict the response direction of six covariates based on prior knowledge of the Tegu's ecology. A priori, we expected that the covariates measured should represent key habitat features for the species (i.e. temperature, forest edge, open habitats) or elements possibly avoided by the species, based on the hypothesis that poaching would have a negative effect on patch occupancy. We used line‐transect surveys to estimate density and abundance. Camera‐traps were used to estimate patch occupancy by the Tegu. Estimated density for S. merianae was 0.21 ± 0.02 Tegus/ha and estimated population size was 4990 ± 521 individuals. Patch occupancy was best described by two covariates: poaching intensity and distance to the forest edge. Detectability was affected by three covariates: poaching intensity, tree density and temperature. Our study presents robust information on abundance and density, habitat use, and activity of S. merianae in the VNR and is the first study providing data on the effects that poaching has on patch occupancy of this lizard. The data indicated that the occupancy and detectability of this species were influenced by a set of factors, providing information that can be useful in management plans in areas where this species can potentially decline and in areas where it may be introduced.  相似文献   

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