首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 62 毫秒
1.
Two species of reptile ticks, Amblyomma dissimile Koch and Amblyomma torrei Pérez Vigueras (Acari: Ixodidae), are reported from the Bahama Islands for the first time. The widespread neotropical (including the Caribbean and southern Florida) A. dissimile was recovered on Andros Island from three species of reptiles all for the first time: the Andros iguana Cyclura cychlura cychlura Cuvier, the Andros curly tail lizard Leiocephalus carinatus coryi Schmidt, and the Andros boa Epicrates striatus fowleri Sheplan and Schwartz. The iguana tick A. torrei, previously known only from Cuba, Puerto Rico and the Cayman Islands, was recovered in the Exuma Islands from the Exuma iguana Cyclura cychlura figginsi Barbour. Mean numbers of ticks per host were as high as 36.6 on Mangrove Cay, Andros Island, and 25.8 on Pasture Cay in the Exuma Islands.  相似文献   

2.
Bird populations, especially on islands, have declined or gone extinct due to overhunting, habitat loss and fragmentation, and adverse effects of the introduction of non-native species. Bahama Swallows (Tachycineta cyaneoviridis), endangered secondary cavity nesters that breed on only three islands in the northern Bahamas, are an island species with a declining population, but the causes of this decline are unknown. During four breeding seasons on Great Abaco Island (2014–2017), we identified cavity-nesting resources used by breeding swallows in native pine forest and other habitats, and estimated phenology and breeding parameters from a subset of nests. Bahama Swallows nest in cavities in a variety of structures, but rely most on woodpecker-excavated cavities in pine snags and utility poles. Swallows nesting in cavities in pine snags had higher fledging success (92%) than those nesting in cavities in utility poles (50–62%), which were concentrated in non-pine habitat that may expose swallows to predation and increased competition for nest cavities from other species. The high reproductive success of Bahama Swallows nesting in the pine forest indicates that the decline in population cannot be attributed to poor productivity on southern Great Abaco. However, our results suggest that the dependence of Bahama Swallows on cavities excavated by Hairy Woodpeckers (Dryobates villosus) for nesting sites may be a factor in their decline, and highlight the potential importance of the protection and management of pine forests in future efforts to ensure the survival of Bahama Swallows.  相似文献   

3.
Black-shouldered Kite (Elanus caeruleus) is a well-known raptor that inhabits open areas such as oil palm plantation or paddy field. To determine preferable habitat and nesting site of Black-shouldered Kite in oil palm landscape, we conducted a study on Black-shouldered Kite’s nesting biology in Carey Island, Selangor, Malaysia. We divided the island into six types of habitat and conducted road-side count of Black-shouldered Kite from April 2009 to February 2011. Whenever the Black-shouldered Kite was detected, we thoroughly searched the surrounding area for their nest. In total, we have recorded forty nests. The nests were built on 15 species of trees but most of the trees shared common physical characteristics. Some novice breeders also used oil palm tree as their nesting site. Structure and building materials of nests constructed on oil palm trees were different from nests built on other trees. Of all breeding attempts, only four nests which were located in residential area adjacent to young oil palm habitat were successful. Among important characteristics of successful nesting site include taller trees with strong branches and good leaf coverage. These trees not only protect nests from predator detection (except from other predatory birds) and physical environment but also facilitate Black-shouldered Kite’s foraging activities by providing good vantage point.  相似文献   

4.
ABSTRACT.   Although many studies have revealed intraspecific variation in the number of broods raised per breeding season, less is known about the causes of variation between species. We monitored the breeding behavior of congeners traditionally thought to raise one brood per breeding season, Orchard Orioles ( Icterus spurius ) and Baltimore Orioles ( I. galbula ). Both species have similar habitat and nesting requirements. We captured and banded orioles at three study sites in Maryland in 2004 and 2005. No pairs of Baltimore Orioles ( N = 26) were double brooded, whereas 8 of 24 pairs (33%) of Orchard Orioles had a second brood and 7 of 16 pairs (44%) of Orchard Orioles that successfully raised a first brood also successfully raised a second brood during the same breeding season. Our findings provide the first documentation of double brooding by Orchard Orioles. The timing of molt and the amount of time and energy devoted to postfledgling parental care may contribute to this difference between species in terms of the number of broods per breeding season.  相似文献   

5.
Ipomoea microdactyla Griseb. (Convolvulaceae) is restricted to the Bahamian archipelago, Cuba, and southeastern Florida. The species is listed as a state endangered species in Florida, where it is mostly restricted to the hyperfragmented pine rockland of Miami‐Dade County. Using seven DNA microsatellite loci, we assessed levels of genetic diversity for 12 populations of this species from Andros Island in the Bahamas (six sites), Cuba (one site), and Florida (five sites). We found significantly greater mean numbers of alleles, and higher mean values for both observed and expected heterozygosity in populations from the continuous forest on Andros than those from the habitat fragments in Florida. It is unknown if these patterns of genetic diversity in the Florida populations are the result of habitat fragmentation or founder effects. The population from Cuba exhibited relatively high levels of genetic variation, suggesting that this island is a major center of diversity and dispersal for this species. It appears that hybrid introgression for I. carolina alleles within I. microdactyla individuals occurred at a single site on Andros Island. Overall, the mean inbreeding coefficient value was 0.089, suggesting low levels of inbreeding. The highest inbreeding coefficient values were mostly recorded in Florida. Two groups were revealed, one containing the populations from Florida, and the second one encompassing those from the Bahamas and Cuba. Our results highlight the negative genetic consequences of habitat fragmentation and support initiatives recently established to establish corridors to connect the remnants of the pine forest of the Miami‐Dade County.  相似文献   

6.
This paper reports on the nesting ecology of blue-and-yellow macaws (Ara ararauna) and the structure, conservation, and management of the Mauritia flexuosa palm swamps where they nest: clutch size averaged 2.6 and the number of chicks fledged per nesting attempt was 0.5. Macaws nested in tall dead palms in healthy palm swamps and in palms of all heights in open dieing palm stands. All nesting palms rose well above the surrounding vegetation presumably to discourage terrestrial predators. PVC nest boxes failed to attract nesting blue-and-yellow macaws. A small section of palm swamp was managed to encourage macaw nesting by cutting the tops off of M. flexuosa palms and clearing the understory vegetation. The palms remained standing from 4 to 7 years and were occupied by nesting macaws at a rate of 24%. The data presented here suggest that cutting five palms a year in perpetuity would produce a stand of approximately 20 standing dead palms used by 6 or more pairs of macaws annually. However, macaw occupancy rates would depend on the density of macaws and density of naturally occurring nest sites. This management scheme could be conducted on a 100-year rotation in an area of 1–4 ha or more depending on the palm density. Such a colony could be used to increase reproductive success of blue-and-yellow macaw populations, create a valuable ecotourism resource, and concentrate macaw nesting in protected areas.  相似文献   

7.
Marbled Murrelets (Brachyramphus marmoratus) are listed as threatened in the portion of their range extending from British Columbia to California due to loss of nesting habitat. Recovery of Marbled Murrelet populations requires a better understanding of the characteristics of their nesting habitat in this part of their range. Our objective, therefore, was to describe their nesting habitat in Washington State and Vancouver Island, British Columbia. We captured Marbled Murrelets from 2004 to 2008, fitted them with radio transmitters, and followed them to nests (N = 20). We used Cohen's unbiased d effect size to assess differences between forest plots surrounding nest sites and nearby control sites (N = 18). Nest sites had less canopy cover of the dominant conifers and fewer, but larger, trees than control sites. Nest sites also had greater percentages of trees with platforms >10 cm diameter and >15 cm diameter, and more platforms of these sizes than control sites. The mean diameter at breast height of nest trees was 136.5 cm (range = 84–248 cm) and all but one nest was in dominant or co‐dominant tree species. At the landscape scale, we used vegetation maps derived from remotely sensed data and found greater canopy cover, higher density of mature trees, more platforms >10 cm/ha, and more old‐growth habitat at nest sites than at random sites. Our findings suggest that, at the site scale, nesting Marbled Murrelets selected the most suitable features of forest structure across expansive potentially suitable habitat. Our landscape‐scale analysis showed that habitat features in nesting stands differed from those features in available stands in the murrelet's range in Washington. We also found that stands with nests were less fragmented than available forest across murrelet range. All nest sites of radio‐tagged birds in Washington were in protected areas in mostly undisturbed forest habitat. Conservation of these areas of inland nesting habitat will be critical to the recovery of Marbled Murrelet populations.  相似文献   

8.
The Key Largo woodrat (Neotoma floridana smalli) and Key Largo cotton mouse (Peromyscus gossypinus allapaticola) are federally endangered subspecies endemic to the tropical hardwood hammocks of Key Largo, Florida. Woodrats are considered generalists in habitat and diet, yet a steady decline in natural stick nests and capture rates over the past several decades suggests that they are limited by the availability of nesting habitat due to habitat loss and fragmentation. The more specialized Key Largo cotton mouse appears to rely on old growth hammock, a habitat type that is rare following past land clearing. In 2004, the U.S. Fish and Wildlife Service started building supplemental nest structures to restore habitat quality and connectivity for these endangered rodents, but nest use requires evaluation. We used camera traps and occupancy models to evaluate the factors influencing woodrat and cotton mouse use of the supplemental nests. We detected woodrats at 65 and cotton mice at 175 of 284 sampled nest structures, with co‐occurrence at 38 nests. Woodrat nest use followed a gradient from low nest use in the north to high nest use in the south, which might relate to the proximity of free‐ranging domestic cat (Felis catus) colonies in residential developments. Cotton mouse nest use, however, was related positively to mature hammock and related negatively to disturbed areas (e.g. scarified lands). The two species occurred independently of each other. Stick‐stacking behavior was observed at supplemental nests and, although it was correlated with detection of woodrats, it was not a strong predictor of their occurrence. We suggest that nest supplementation can be an important tool for species recovery as habitat quality continues to improve with succession.  相似文献   

9.
Phytoplasmas associated with lethal decline diseases of the coconut palm (Cocos nucifera) in west and east Africa were detected by the specific amplification of their 16S rRNA genes. The primers used were based on conserved mollicute-specific and coconut-phytoplasma 16S rRNA gene sequences. Phytoplasma 16S rDNA was amplified from all African decline affected palms, some periwinkle maintained phytoplasmas, but not from healthy palms, infected palms from Florida or from the Cocos spiroplasma and Acholeplasma sp. mollicutes. African phytoplasmas were also detected by DNA hybridisation using two probes from the palm lethal yellowing phytoplasma from Florida. Probes hybridised at moderate stringency to dot blots of lethal decline affected palms from Africa, indicating possible genetic relationships between different coconut phytoplasmas. RFLP analysis of rDNA fragments (length c. 1.45 kbp) detected polymorphisms, indicating that the pathogens found in west and east Africa are not identical. This provides a useful tool for further epidemiological studies of African coconut phytoplasmal diseases.  相似文献   

10.
Feral European Honey Bee (Apis mellifera) has been identified as a potential nest competitor for Australian hollow nesting species, but few studies have investigated the impact of feral honey bee competition on Threatened species. Our study used data from Glossy Black‐cockatoo (Calyptorhynchus lathami halmaturinus) nests on Kangaroo Island, monitored and managed over an 11‐year period, and found 12% of nests became occupied by feral honey bees during that period. Our results indicate that feral honey bees were less likely to occupy nest boxes made of PVC (5%) compared with wooden nest boxes (24%) or natural hollows in Eucalyptus trees (14%). The removal of feral honey bee hives from nests is a priority for long‐term conservation of glossy black‐cockatoos on Kangaroo Island. We recommend that PVC nest boxes are chosen for future nesting habitat restoration, due to the more frequent use of wooden nest boxes by feral honey bees.  相似文献   

11.
Symptoms of vegetative malformation were observed on coconut palms (Cocos nucifera L.) in the Qeshm Island, Bandar Abbas and Minab, in Hormozgan province, southern Iran. The symptoms included misshapen and dwarfed leaves with shortened, thickened and tightened leaflets in wavy and zigzag form. The aim of this study was to identify the causal pathogen of coconut palm malformation and complete Koch's postulates for putative pathogen. Small pieces of surface‐disinfested malformed vegetative tissues of coconut palms were cultured on potato dextrose agar (PDA) medium. Fusarium isolates were permanently obtained from the symptomatic tissues. Sequence data from the internal transcribed spacer region (ITS1–5.8S‐ITS2) and translation elongation factor 1 alpha (TEF‐1α) gene were used for molecular identification of the isolates. BLAST search of the sequences showed 99%–100% identity to several Fusarium proliferatum strains in the GenBank, FUSARIUM‐ID and Fusarium MLST databases. A phylogeny inferred using individual sequence data from ITS region and TEF‐1α gene placed our isolates together with the other F. proliferatum sequences retrieved from the GenBank. Pathogenicity tests were carried out using one‐year‐old healthy coconut palm seedlings and conidial suspensions (106 conidia/ml) of the F. proliferatum isolates. The first visible symptoms appeared on newly produced leaves of the inoculated seedlings during the 16th week after inoculation, wherease no disease symptoms were observed on the control plants until the end of the experiment. Reisolation from symptomatic tissues of the inoculated seedlings yielded isolates of F. proliferatum with morphological and molecular characteristics identical to those of the isolates used for inoculations. This is the first report of coconut palm malformation caused by F. proliferatum worldwide.  相似文献   

12.
Patterns of distribution and abundance of coral reef fish depend in part on recruitment of a pelagic larval stage, on subsequent dispersal among habitats, and survival of new recruits. We studied recruitment of five species of Stegastes and two species of Chromis damselfish onto reef habitats of St. Thomas, USVI during one year. The two study sites, Flat Cay and Outer Brass Island, were on the southern and northern sides of St. Thomas, respectively. At both sites, recruitment occurred largely in the summer months, although one species (Stegastes planifrons) showed significant winter recruitment at Flat Cay. The onset of increased summer recruitment in 1992 of other species occurred several weeks later and was shorter in duration at Outer Brass Island than at Flat Cay, perhaps indicating differences in oceanographic conditions (currents etc.) or spawning cycles between sites. The two Chromis species showed lunar periodicity of settlement at Flat Cay. At Flat Cay, recruits of three species (S. leucostictus, S. diencaeus and S. planifrons) were associated with conspecifics possibly due to preferential settlement. Similarly, new recruits were more often found near live coral than coral rubble, and very few occurred on sand habitat. Substratum complexity was a poor predictor of recruitment within a habitat, although larger juveniles of some species were more common on more complex substrate. Contrary to other studies, there were no apparent depth preferences among recruits, although larger juveniles of two Stegastes species were found more often in deeper water. It appears that within habitats, newly arriving larvae may be attracted first to the presence of conspecifics and secondarily take up position adjacent to live coral. Apparent survivorship of some Stegastes species and one Chromis species was higher at Outer Brass Island than at Flat Cay, and may partly compensate for lower recruitment of some species at Outer Brass Island.  相似文献   

13.
Avian ecology and behaviour data provides crucial information for bird conservation and management, but are still missing for many species, particularly in developing countries. This study examines habitat utilisation, nesting behaviour, anthropogenic disturbances and impacts on agricultural crops of Village Weaver Ploceus cucullatus and Vieillot’s Black Weaver Ploceus nigerrimus in Mbalmayo District, Cameroon. Abundance was estimated by nest counts and point counts of birds at 40 previously located colonies, where also tree metrics and anthropogenic disturbances were measured. In total, more than 1 700 birds of the two species were estimated within a 9 km2 study area, divided into two blocks and five different habitat types. Village Weavers were generally more abundant, especially in the urban habitat, whereas Vieillot’s Black Weavers were most numerous in the rural habitat. Among the tree species used for nesting, mango Mangifera indica and African border tree Newbouldia laevis had the highest nest counts, which also was positively related to canopy cover diameter. Traffic noise disturbance was associated with lower bird and nest counts, whereas the opposite was observed on farming disturbance. The relative impacts on agricultural crops were estimated for African oil palm Elaeis guineensis (38%), maize Zea mays (36%), Musa spp. (18%) and Mangifera indica (8%). The implications for long-term coexistence between farmland birds and humans are discussed, and the challenge is to minimise both kinds of bird–human interactions, i.e. anthropogenic disturbances and agricultural crop damage.  相似文献   

14.
15.
We studied the effects of habitat composition and distance from edges on nesting success and brood parasitism of forest birds in the Kaskaskia River Bottoms, one of the largest remaining tracts of floodplain forest in the agricultural Midwestern United States. Our goal was to help the private landowners, who have maintained this region in forest cover, enhance the value of these forests for nesting birds. We measured nest predation rates and levels of brood parasitism of four species, the indigo bunting Passerina cyanea, Acadian flycatcher Empidonax virescens, northern cardinal Cardinalis cardinalis and prothonotary warbler Protonotaria citrea in relation to distances from natural and anthropogenic edges and proportion of natural and anthropogenic habitats within fixed radii around nests. We predicted that nesting success would increase with increasing distance from anthropogenic habitats and with increasing land cover in natural habitats. Our results showed no strong effect of any of these variables on avian nesting success, although parasitism levels increased slightly with increasing proportion of agricultural land around nests for two of the species. Nevertheless, nesting success for at least three of these species was much higher than in more fragmented forest tracts elsewhere in the agricultural Midwest where most forest tracts appear to be population sinks for most species. These results suggest that forest tracts in the Kaskaskia may be saturated with nest predators and brood parasites, but are not super‐saturated in a way that would cause these tracts to become ‘black hole’ population sinks. Our data further suggest that, as long as landowners maintain their private landholdings in forest cover, the details of how they manage their land may have little effect on songbird nesting success. These results also suggest that reforestation efforts in areas with many openings may still benefit forest birds.  相似文献   

16.
The microfungi of three palm species were investigated in their natural habitats and in habitats where the palms were cultivated outside their natural ranges. The palms that were selected differed in their habitats and ecology. Archontophoenix alexandrae is endemic to tropical rainforests in Australia, Cocos nucifera is pan‐tropical and Trachycarpus fortunei occurs in warm‐temperate China. Different assemblages of fungi were found in association with palms in temperate regions as compared to those in tropical regions. These differences were more related to climatic influences than to the hosts sampled, as few fungi were host‐species specific. The status of the hosts at the site, i.e. indigenous or introduced, and the degree of disturbance of the habitats within which the palms grew were also influential. When sampled in its natural habitat, Archontophoenix alexandrae had a distinct palmicolous mycota typical of other palms in tropical rainforests. Outside of the palm’s natural habitat, a widely different mycota were recorded that comprised tropical species of a more plurivorous nature. A similar plurivorous assemblage characterized the fungi associated with Cocos nucifera, probably due to the palm’s long history of cultivation. Similarly, plurivorous, but temperate or widespread fungi were associated with Trachycarpus fortunei, both within and outside of its natural habitat. This palm is also highly cultivated. A reduction in palm fungi associated with palms in disturbed habitats has implications for conservation of these fungi. However, it is acknowledged that the data for fungal diversity and distribution is incomplete and fragmentary.  相似文献   

17.
Finschhafen disorder (FD) affects coconut and oil palms in Papua New Guinea (PNG). It is characterised by yellow‐bronzing of fronds which begins at the tips and progresses towards the petiole. Although the planthopper Zophiuma lobulata (Hemiptera: Lophopidae) has been posited as a cause of FD, the basis of the relationship has not been established. Studies conducted previously on FD predate the availability of DNA‐based techniques to test for the involvement of plant pathogens such as phytoplasmas that cause yellows‐type diseases in many plant taxa and are transmitted by the order of insects to which Z. lobulata belongs. In this study, polymerase chain reaction (PCR) assays found no evidence of phytoplasmas or bacteria‐like organisms (BLOs) in tissues of coconut and oil palm symptomatic for FD and from Z. lobulata feeding on these plants. Further studies involved releasing Z. lobulata adults and nymphs onto caged, potted coconut and oil palms and onto palm fronds enclosed in mesh sleeves. In both experiments, chlorotic symptoms on the palms were observed in the presence of Z. lobulata. Insect‐free control palms did not exhibit chlorotic symptoms of FD. In the frond sleeve experiment, only the fronds where Z. lobulata fed developed chlorosis indicating that the disorder is not systemic. Unlike most yellows‐type diseases associated with Hemiptera, this study indicates that FD is because of a direct feeding effect on palms by Z. lobulata rather than transmission of a pathogen.  相似文献   

18.
Aquatic turtles worldwide are plagued with habitat loss due to development and shoreline alteration that destroys the terrestrial–aquatic linkage which they must cross to reproduce successfully. Furthermore, nesting habitat loss can concentrate nesting, increasing nest predator efficiency. We describe how the Paul S. Sarbanes Ecosystem Restoration Project at Poplar Island created nesting habitat for Malaclemys terrapin (Diamondback Terrapin), and document nesting success in response to construction progress and the absence of raccoons and foxes, the primary nest predators. We monitored terrapin nests throughout the nesting seasons from 2002 to 2011 to determine overall and within‐nest survivorship. Female terrapins began nesting on the restoration project within 1 year but planned construction during the study eliminated some nesting areas and opened previously inaccessible areas. Overall, nest survivorship was considerably higher than mainland nesting areas due to the absence of raccoons and foxes on the island and within‐nest survivorship was similar. Egg size, hatchling size, and the frequency of shell scute anomalies were similar to other terrapin populations, suggesting normal developmental conditions on the island. We documented annual variation in hatchling size that correlated negatively with mean air temperature during the incubation season. Our results indicate that restored or created isolated island habitat can be located rapidly by terrapins and can become an important source of recruitment in regions where nesting habitat is limited and predation is high. Poplar Island illustrates how habitat loss and restoration can affect turtle populations by revealing the changes in nesting patterns and success in newly created, predator‐free habitat.  相似文献   

19.
We studied nesting habitat selection of the endangered non‐migratory Osprey Pandion haliaetus population of the Canary Islands and evaluated the effect of human expansion in recent decades. Compared with randomly selected potential nest‐sites, Osprey nests were more frequently found on taller, southwest‐facing cliffs, characterized by lower human pressure and closer to Yellow‐legged Gull Larus michahellis colonies and Barbary Falcon Falco pelegrinoides breeding sites. Furthermore, changes in some breeding habitat features have been detected in recent decades. According to our predictive models, large areas of suitable habitat are available but unoccupied in the Canaries, and human activities are probably limiting the settlement and dispersion of new pairs.  相似文献   

20.
Cyclura ricordii is an endemic iguana from Hispaniola Island and is threatened on the IUCN Red List. The main threats are predation by introduced mammals, habitat destruction, and hunting pressure. The present study focused on two nesting sites from Pedernales Province in the Dominican Republic. The hypothesis that natal philopatry influences dispersal and nest‐site selection was tested. Monitoring and sampling took place in 2012 and 2013. Polymorphic markers were used to evaluate whether natal philopatry limits dispersal at multiple spatial scales. Ripley's K revealed that nests were significantly clustered at multiple scales, when both nesting sites were considered and within each nesting site. This suggests a patchy, nonrandom distribution of nests within nest sites. Hierarchical AMOVA revealed that nest‐site aggregations did not explain a significant portion of genetic variation within nesting sites. However, a small but positive correlation between geographic and genetic distance was detected using a Mantel's test. Hence, the relationship between geographic distance and genetic distance among hatchlings within nest sites, while detectable, was not strong enough to have a marked effect on fine‐scale genetic structure. Spatial and genetic data combined determined that the nesting sites included nesting females from multiple locations, and the hypothesis of “natal philopatry” was not supported because females nesting in the same cluster were no more closely related to each other than to other females from the same nesting site. These findings imply that nesting aggregations are more likely associated with cryptic habitat variables contributing to optimal nesting conditions.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号