The Potential Of Uncut Patches To Increase The Nesting Success Of Grassland Songbirds In Intensively Managed Hayfields: A Preliminary Study From The Champlain Valley Of Vermont

Changes in land use and intensification of agricultural practices are associated with declines of grassland songbird populations in North America. Hay harvests in the northeastern United States are occurring earlier and more frequently today than 30 years ago, resulting in substantially decreased nesting success of grassland songbirds on early-hayed fields. Few studies have examined whether uncut patches within fields cut during the breeding season can increase the nesting success of grassland songbirds. Twenty-nine artificial nests were placed in 17 uncut patches (mean = 0.337 ha, median = 0.103 ha) on four early-hayed fields in Shelburne, VT. Only one of the 29 artificial nests was depredated. Despite the small sample size, these data suggest that minimal nest cover may allow some reproductive success during hay harvest. Investigating the effect of patch size variation, patch placement, and vegetation structure within uncut patches would prove useful for potential management strategies. While most farmers will be unable to find and cut around grassland songbird nests, larger uncut patches (i.e., ≥1 ha) encompassing areas with high avian nesting densities may be a useful management strategy for grassland birds in intensively managed hayfields of the Champlain Valley of Vermont and New York or similar dairy-dominated agricultural landscapes

Morphological Abnormalities in Vitamin B6 Deficient Tarsometatarsal Chick Cartilage

The aim of this study was to test the hypothesis that deficiency of vitamin B6 would produce morphological characteristics of osteochondral lathyrism. To accomplish this goal, morphological characteristics of chick cartilage in which lathyrism was produced by two separate dietary regimens was compared to morphological changes encountered in vitamin B6 deficiency. Vitamin B6 deficiency should reduce activity of lysyloxidase needed for producing intermolecular cross-links. The question to be addressed was: would this latter deficiency impair collagen morphological features and secondarily other structures indirectly by reducing collagen molecular assembly? Failure of cross-linking of collagen in the positive controls was related to a lack of functional aldehyde cross-link intermediates which are blocked by homocysteine and aminoacetonitrile. Day-old-male Lohmann chicks were fed adequate (6 mg/kg) or vitamin B6-deficient diets. Cross-link defects were induced by homocysteine-rich diets (0.6% w/w) or a diet containing aminoacetonitrile (0.1% w/w). Animals were sacrificed at 6 weeks of age and Ossa tarsalia articular cartilage specimens, as well as the proximal end of tarsometatarsus were dissected from the tibial metatarsal joint, a major weight-bearing site. Light microscopic observations revealed reduction of subarticular trabecular bone formation, concurrent with overexpansion of the hypertrophic cell zone. Ultrastructural electron microscopy observations of articular fibro-cartilage indicated significant thickening of collagen fibers in vitamin B6 deficient birds, as well as the positive controls in comparison to that of cage-matched control birds. It was concluded that vitamin B6 deficient cross-linking may be responsible for the observed delay in bone development and aforementioned cartilage histological alterations