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Stephan J. Schoech Eli S. Bridge S. James Reynolds Jonathan W. Atwell 《Biological conservation》2008,141(1):162-173
The federally threatened Florida Scrub-Jay (Aphelocoma coerulescens) has suffered dramatic losses in recent years primarily because of overdevelopment of its unique scrub habitat. Ensuring the survival of this species will require not only measures to reduce habitat loss, but also efforts to increase the numbers of birds in small scattered populations to a point at which they are resilient to extinction from stochastic population fluctuations. Here we evaluate the utility of providing supplementary food during the pre-breeding season as a means of increasing the reproductive output of Florida Scrub-Jays. Data collected from 2000 to 2007 at Archbold Biological Station in south-central Florida indicate a marked effect of supplemental feeding on reproductive output. This increased output appeared to result primarily from larger clutch sizes produced by supplemented female breeders as a result of their advanced laying. Supplementation also increased offspring survival probabilities and the early laying permitted more renesting attempts. Furthermore, annual variation in several reproductive measures was dampened in supplemented birds, suggesting that supplemental feeding may reduce environmental or stochastic effects on reproductive output. Although a number of potential problems may be associated with supplemental feeding (e.g., predator entrainment and increased opportunity for disease transmission), it can serve as a valuable tool for management agencies that wish to rapidly increase local carrying capacity. In addition, food supplementation might benefit translocation efforts both by increasing the number of potential translocation candidates from a donor population and then by supplementing the newly established population to promote rapid growth. 相似文献
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IMAGING DIAGNOSIS—USE OF RADIOGRAPHY,COMPUTED TOMOGRAPHY,AND ENDOSCOPY IN THE DIAGNOSIS OF ESOPHAGEAL PERFORATION BY AN EXTRA‐LUMINAL TRACHEAL RING PROSTHESIS IN A GOLDEN RETRIEVER 下载免费PDF全文
A 6‐year‐old neutered male, Golden retriever presented with regurgitation and excitement‐induced coughing. Two years prior, extra‐thoracic tracheal collapse was diagnosed and extra‐luminal tracheal ring prostheses were placed. Radiographs at presentation showed mineralized and undulant cervical tracheal cartilages. A dorsally broad‐based soft tissue opacity bulged into the caudal cervical tracheal lumen. Esophageal dysmotility and barium accumulation were identified at this level on contrast esophography. Computed tomography showed migration of a prosthetic tracheal ring, resulting in perforation of the esophagus. Hair, foreign material, and dynamic tracheal narrowing were identified on esophagoscopy and tracheoscopy, respectively. Esophagostomy and foreign body removal were performed. 相似文献
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During the course of the 20th century many changes took place in the area encompassing Israel and the Palestinian Authority (hereafter Israel; ca. 28,000 km2): the human population grew from ca. 650,000 inhabitants during 1900–1903 (Rupin, 1920) to ca. 10 million in 2008, i.e. a 16-fold increase. This population increase was accompanied by an increase in land use for human needs – agriculture, aquaculture, forestry, construction of buildings and roads, etc., and a dramatic rise in the standard of living.Here we compare the status (distribution and abundance) of the 227 bird species that are breeding or have bred in Israel from the beginning of the 20th century to the present day. For each species we documented the environmental factors presumed to have affected it, and examined the effects of taxonomic order, body mass, diet, world and local distribution and nest location on the status of the avifauna. We found that 73.6% of the bird species breeding in Israel had undergone a change in their status during the studied period. While several of the examined factors were significantly related to the observed changes, some of them were also interrelated to some degree, making it difficult to single out the factor responsible for a particular change. The main reasons for the changes were nonetheless assessed as habitat change, introduction of invasive species and poisoning. Habitat change had many forms, most of which are related to agriculture, including irrigation, aquaculture and construction of water reservoirs; but also included afforestation, preservation of the natural forest, urbanization, gardening and the introduction of exotic plants. Habitat change was responsible for a population decline in 64 species and population increase in 62 species. Thirteen species, mostly Falconiformes, were impacted by poisoning. Sixteen invasive species, all of tropical origin, were introduced, of which seven were Psittaciformes. Although changes occurred throughout the country, the birds inhabiting the Mediterranean region were more affected than those inhabiting the desert region, reflecting the denser human population in the former region. 相似文献