Quality of Flooded Rice and Fallow Fields as Foraging Habitat for Little Blue Herons and Great Egrets in the Everglades Agricultural Area, USA (original) (raw)
Related papers
Biological Conservation, 2006
While it is widely understood that local abundance of benthic invertebrates can greatly influence the distribution and abundance of wetland birds, no studies have examined if wetland landscape context can mediate this relationship. We studied the influence of wetland food abundance and landscape context on use of agricultural wetlands by wintering dunlin (Calidris alpina) and killdeer (Charadrius vociferus) in the Willamette Valley of Oregon, USA, over two winters (1999-2000, 2000-2001) of differing rainfall and subsequent habitat distribution. We monitored bird use (frequency of occurrence and abundance) at a sample of wetlands differing in local food abundance (density and biomass) and landscape context [adjacent shorebird habitat (defined as ha of wet habitat with less than 50% vegetative cover and within a 2-km radius) and nearest neighbor distance]. We evaluated predictive models for bird use using linear regression and the Cp criterion to select the most parsimonious model. During the dry winter (2000-2001), dunlin exhibited greater use of sites with higher invertebrate density and biomass but also with more adjacent shorebird habitat and closest to a wetland neighbor. However, neither landscape context nor food abundance were important predictors of dunlin use during the wet winter (1999-2000). Use of sites by killdeer was unrelated to either local food abundance or landscape context measures during both winters. Our findings contribute to a growing recognition of the importance of landscape structure to wetland birds and highlight a number of implications for the spatial planning and enhancement of wetlands using a landscape approach.
1981
Summary. -In Northern Italy, the distribution of heronries seems related witn the abundance of rice fields. We studied the diet of Night Heron and Little Egret in a zone with abundant rice, in order to ascertain the extent to which the prey are taken in agricultural wet habitats (rice, irrigation canals) or elsewhere (rivers, marshes). We collected food regurgitated by the nestlings in the heronries, complementing the data in rice fields by direct observation of adult Night Herons feeding and by sampling the available prey.
Distribution of Waterbirds in Rice Fields and Their Use of Foraging Habitats
Waterbirds, 2015
Over the course of a year, rice fields display spatial and temporal differences according to farming management practices, providing a succession of habitats throughout the crop-growing cycle for various waterbird species. However, few studies have assessed the influence of the spatial and temporal differences produced by rice field farming management practices on waterbird species during a year. The present study investigated spatial and temporal patterns of species distribution and examined the factors that affect waterbird selection of foraging habitats in the rice fields located in the midwestern part of South Korea from April 2009 to March 2010 and from April 2011 to March 2012. Waterbird species represented strong seasonality and selectively used different field types at a fine spatial scale. The selection of field type depended more on field structures that were related to the vulnerability of prey items than on prey abundance in rice fields. Water level was an important factor that affected shorebird selection of foraging habitat, and they chose habitats with different water levels according to their body size. The density of rice plants was a critical factor affecting the selection of habitats by herons, because densely planted fields inhibited their access to food. The presence of rolled straw in rice fields affected the distribution of waterfowl. These results demonstrate that farming management practices, which determine prey accessibility, strongly affect the use of rice field habitats by waterbirds. Our knowledge of these relationships should be incorporated into conservation practices protecting the various waterbird species that use rice fields.
Wetland Waterbird Food Resources Increased by Harvesting Invasive Cattails
The Journal of Wildlife Management
The conservation of many freshwater marsh waterbirds (i.e., waterfowl, shorebirds, wading birds, and secretive marshbirds) in the Laurentian Great Lakes requires managing invasive emergent macrophytes, which degrade waterbird habitat by creating dense, litter-clogged stands, and excluding plants that produce nutritionally balanced and high-energy food (seeds, tubers, and submerged aquatic vegetation). The most commonly used management approach in the United States Great Lakes region involves the application of herbicides, which can stimulate waterbird forage plants but does not address the accumulation of plant litter, the underlying cause of plant community diversity loss and habitat degradation. We experimentally evaluated the effects of an alternative approach, harvesting invasive plants and their litter followed by flooding, on plant communities, focusing on the effects of these treatments to increase the abundance of high-energy wetland plants. At the Shiawassee National Wildlife Refuge in Michigan, USA, we experimentally treated an invasive cattail (Typha × glauca)-dominated wetland in August and September of 2016, 2017, and 2018, using a randomized block design with 4 blocks and 3 treatments (sediment surface harvest, above ground harvest, and control). We monitored the effects of these treatments on the abundance and dominance of waterbird forage-producing plants, plant diversity, and plant communities prior to (Jul 2016) and during the summer following each treatment (late Jul or early Aug 2017, 2018, and 2019). Additionally, we used pre-and post-treatment waterbird use-day data collected at the unit scale and compared values with satellite imagery-derived land cover changes. Compared to control plots, 3 years of harvesting and flooding significantly increased plant species diversity, increased the abundance of waterbird seed-and tuber-producing plant species by 5 times, and increased annual plant dominance by more than 10 times, while substantially reducing all measures of cattail and its litter. Use-days increased for total waterbirds, including waterfowl and dabbling ducks, following treatment. Cattail cover decreased and open water and non-cattail emergent vegetation cover increased. Harvesting invasive plant biomass coupled with flooding promoted a plant community composition and structure beneficial to waterbirds.
Foraging Habitat for Bird Species or Bird Diversity in Wetland Design
1999
This technical note provides guidelines for creating, restoring, or enhancing wetlands with foraging habitat intended to 1) support selected bird species, or 2) maximize bird diversity. Information in this technical note is applicable to wetlands ranging from damp or shallowly flooded terrestrial areas to deeper semi-permanent and permanent wetlands, including ponds and lakes. This technical note also lists a number of publications with information about designing wetlands intended to support birds. Information in this technical note is not relevant to forested wetlands. BACKGROUND: Although less than 5 percent of the land area of the contiguous United States is classified as wetlands, almost a third of the region's bird species inhabit wetlands. As wetland area has declined over the past 200 years, the abundance of wetland bird life has also declined, in many cases at rates exceeding 1-2 percent per year and in some recently documented cases by rates that exceed 5 percent per year. Of the 29 federally endangered and threatened bird species in the contiguous United States, 16 are wetland and coastal inhabitants.