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Permanent URI for this collectionhttps://hdl.handle.net/1969.6/86486

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An inter-sensor calibration and atmospheric correction system for long-term time series of AVHRR imagery for coastal waters.
(GIScience & Remote Sensing, 2013-06-14) Gibeaut, James C.; Su, Lihong
The Advanced Very High Resolution Radiometer (AVHRR) data series has more than 30 years of unique and valuable Earth observation imagery available. To use the longterm remote-sensor data, this article presents a system that produces consistent intersensor calibration and atmospheric correction for coastal waters. The system can process all five High Resolution Picture Transmission (HRPT) file formats from the twelve (12) AVHRR sensors that operated from the 1980s to the present. The system has been used to process AVHRR data of three Texas estuaries from 1985 to 2010 to document changes in suspended sediment patterns
The index array approach and the dual tiled similarity algorithm for UAS hyper-spatial image processing
(Geoinformatica, 2016-04-02) Su, Lihong; Huang, Yuxia; Gibeaut, James; Li, Longzhuang
Unmanned aerial systems (UAS) have been used as a robust tool for agricultural and environmental applications in recent years. Remote sensing systems based on UAS typically acquire massive hyper-spatial images in its short turnaround. This paper takes advantage of graphics processing unit (GPU) massive parallel computation in order to process the huge data timely and efficiently. More specifically, this paper presents an index array approach for lens distortion correction and geo-referencing. They are the two essential components in UAS hyper-spatial image processing. The index array approach is also capable of parallelizing image file I/O and the orthoimage generation. In addition, this paper presents the dual tiled similarity algorithm for the image co-registration. The index array approach and the dual tiled similarity algorithm were evaluated using two UAS remote sensing datasets of South Padre island shorelines. The results show that this index array approach was able to speed up at least 10 times the lens distortion correction and the geo-referencing relative to the central processing unit (CPU) computation. This dual tiled algorithm could provide 12 times speedup compared with the CPU similarity computation.
Enabling Data Sharing Through the Gulf of Mexico Research Initiative Information and Data Cooperative (GRIIDC)
(Oceanography, 2016-09) Gibeaut, James
Our ability to improve society’s understanding of the Gulf of Mexico ecosystem, including humans, and to ensure the Gulf ’s long-term environmental and public health requires access to a wide array of data. Understanding the impacts of petroleum pollution and related stressors on marine and coastal ecosystems and human populations calls for the ability to integrate and analyze data from diverse sources, across disciplines, and from varied spatial and temporal scales. One of the more frequent observations hindering determination of Deepwater Horizon spill ecosystem impacts revolved around the lack of baseline data from many disciplines. Data are required to make informed decisions about the management of complex systems, particularly relating to impacts, future response, mitigation, and restoration following spills and natural disasters. Changes in the ways scientists gather, manage, and analyze data are driven, in some cases, by the availability of innovative new data gathering tools and new low-cost computing capabilities. Other changes are driven by how and what data, particularly public health data, are collected and accessed. Society, however, is also demanding change (McNutt et al., 2016). The public wants increased transparency. Decision-makers from all sectors are calling for reproducibility and validation. As public and environmental health become increasingly interconnected, health professionals and policymakers require timely access to reliable and robust monitoring data that provide a baseline for informed decision making to promote the health and well-being of ecosystems and the people who live and work in these systems. The science community is beginning to recognize and address this need for large, accessible, integrated data sets. Recently, the National Oceanic and Atmospheric Administration (NOAA) announced it will be partnering with five Web organizations—Amazon Web Services, Microsoft Azure, IBM, Google, and the Open Cloud Consortium—through a Cooperative Research and Development Agreement (CRADA) to organize and make NOAA’s data more easily accessible and usable (https://www.commerce. gov/news/press-releases/2015/04/ussecretary- commerce-penny-pritzkerannounces- new-collaboration-unleash). Access to data generated by the Gulf of Mexico Research Initiative (GoMRI) can make a direct difference to understanding, responding to, and mitigating future oil spills. GoMRI recognized this early on in the program’s development, and the Gulf of Mexico Research Initiative Information and Data Cooperative (GRIIDC; https:// data.gulfresearchinitiative.org) serves as an excellent example of how data integration and consistency can provide exponential added value to the research community as a whole. Research investigations funded by GoMRI have resulted in a large pulse of scientific data produced by studies ranging across the program’s five research themes (Shepherd et al., 2016, in this issue). Data sets from laboratory, field, and modeling activities describe phenomena ranging from microscopic fluid dynamics to large-scale ocean currents, from bacteria to marine mammals, and from detailed field observations to synoptic mapping. One of GoMRI’s central tenets is to ensure that all data are preserved and made publicly available, and GRIIDC ensures a data and information legacy that promotes continual scientific discovery and public awareness of the Gulf of Mexico ecosystem. Open data requirements are increasing in number and enforcement. There are many reasons for the effective curation and sharing of data, including (1) providing environmental baselines for gauging the effects of episodic events such as storms or oil spills, (2) increasing the efficiency of the scientific process through reuse of data and providing direction for future data acquisitions, (3) increasing public trust by making data available that are used in applying and developing public policy, and (4) enabling new discoveries through data mining. GoMRI became a leader in the move toward open scientific data in 2011 when BP and the Gulf of Mexico Alliance established in their Master Research Agreement (MRA) a research database from which all data are to be made “fully accessible” with “minimum time delay.” The MRA also charges the GoMRI Research Board with developing data policies and the GoMRI Administrative Unit with administering the research database. The Research Board established that “fully accessible” meant publicly available with documentation (metadata) to make data sets understandable and reusable. Further, the phrase “minimum time delay” was defined as within one year of data acquisition or before publications appear that use the data. This “one-year or before publication” requirement is ambitious and on the forefront of data- sharing policies of research funding organizations. It has caused the program to focus on data management throughout the data life cycle and requires a commitment of time and resources by researchers. It has also created the need for GRIIDC to develop processes and resources for data planning, tracking, and archiving as well as training for researchers. This article describes the structure of GRIIDC and the approach to meeting a stringent open data requirement.
Meeting Regional, Coastal and Ocean User Needs With Tailored Data Products: A Stakeholder-Driven Process
(Frontiers in Marine Science, 2019-06-07) Iwamoto, Melissa M.; Dorton, Jennifer; Newton, Jan; Yerta, Moirah; Gibeaut, James; Shyka, Tom; Kirkpatrick, Barbara; Currier, Robert
New coastal and ocean observing stations and instruments deployed across the globe are providing increasing amounts of meteorological, biological, and oceanographic data. While these developments are essential for the development of various data products to inform decision-making among coastal communities, more data does not automatically translate into more benefits to society. Rather, decision-makers and other potential end-users must be included in an ongoing stakeholder-driven process to determine what information to collect and how to best streamline access to information. We present a three-step approach to develop effective tailored data products: (1) tailor stakeholder engagement to identify specific user needs; (2) design and refine data products to meet specific requirements and styles of interaction; and (3) iterate engagement with users to ensure data products remain relevant. Any of the three steps could be implemented alone or with more emphasis than others, but in order to successfully address stakeholders’ needs, they should be viewed as a continuum—as steps in a process to arrive at effective translation of coastal and ocean data to those who need it. Examples from the Regional Associations of the U.S. Integrated Ocean Observing System (IOOSR ), the Texas General Land Office, and the Vanuatu Meteorology and Geo-hazards Department (VMGD) are woven throughout the discussion. These vignettes illustrate the value of this stakeholder-driven approach and provide a sample of the breadth of flexibility and customizability it affords. We hope this community white paper inspires others to evaluate how they connect their stakeholders to coastal and ocean observing data and provides managers of observing systems with a guide on how to evolve in a manner that addresses societal needs.
Mouse Trap Recovered in Harrier Nest
(Raptor Research, 1983) Gawlik, Dale E.
An annual vole (Microtus sp.) index is an important part of Hamerstrom's study of the Northern Harrier (Circus cyaneus) in central Wisconsin (Hamerstrom, F., Auk 96:370-374, 1979). Vole trapping on her study area began in 1964 and 28,911 trap nights have been accumulated by Hamerstrom and her coworkers through 1981. On 4July 1981 I found evidence that a harrier had stolen a trap.
Naphthalene moth balls do not deter mammalian predators at red-winged blackbird nests.
(Journal of Field Ornithology, 1988) Gawlik, Dale E.; Hostetler, Mark E.; Bildstein, Keith L.
Researchers often use predator repellents to deter mammalian predators from following their scent trails to nests. The effectiveness of repellents is largely unstudied. We tested naphthalene moth balls, a supposed repellent, and found them to be ineffective in deterring mammalian predators at unoccupied Red-winged Blackbird (Agelaius phoeniceus) nests that we supplemented with Northern Bobwhite (Colinus virginianus) eggs.
Reproductive success and nesting habitat of the loggerhead shrike in north-central South Carolina.
(Wilson Bulletin, 1990) Gawlik, Dale E.; Bildstein, Keith L.
Breeding Loggerhead Shrikes (Lank ludovicianus) were studied in the Piedmont physiographic region of north-central South Carolina during the breeding seasons of 1986 and 1987. Sixty-three percent of shrike nests were in red cedar (Juniperus virginiana). Shrikes nesting in red cedar fledged one more young per nest than did shrikes nesting in other trees. First nests were significantly lower and somewhat closer to the trunk of the nest tree than were second nests, suggesting that climatic effects during the nesting season affected nest placement. Within 100 m of shrike nests, short-grass habitats (e.g., pasture, hay fields, and residential lawns) predominated, comprising, on average, more than 80% of the area. Short vegetation around nests may result in increased prey availability. The relatively high reproductive success of Loggerhead Shrikes in this study is similar to that reported by researchers elsewhere, and it does not explain the recent decline in shrike populations in the region.
Conservation Biology and the Evolution of a Land Ethic
(Journal of Raptor Research, 1992) Gawlik, Dale E.
"Conservation biology" is reportedly distinct from other natural sciences because of its focus on a wide array of biota, the long-term scale at which it operates, its holistic nature, its assumption that organisms have an intrinsic value and its direct application of research to a management goal. However, most of what contemporary conservation biologists endorse was previously proposed by Aldo Leopold, and practiced by two of his former students, Frederick and Frances Hamerstrom. That their work with Northern Harriers (Circus cyaneus hudsonius) and Greater Prairie Chickens (Tympanuchus cupidopinnatus) has received widespread recognition is a testimony to the effectiveness of this approach. Conservation biology is only now gaining widespread acceptance probably because of the increasing importance that society has recently placed on the environment. Leopold predicted that society's perception of the environment would move towards what he termed a "land ethic" before the approach endorsed by contemporary conservation biologists could be successful. We may be witnessing the stirring of just such a movement.
Seasonal Habitat Use and Abundance of Loggerhead Shrikes in South Carolina
(Journal of Wildlife Management, 1993) Gawlik, Dale E.; Bildstein, Keith L.
Loss of winter habitat has been implicated in the widespread declines of loggerhead shrik ludovicianus) populations; however, our understanding of what represents winter habitat for this s poor. Thus, we investigated whether shrikes in South Carolina used similar habitats throughout the found that during the breeding season shrikes inhabited areas dominated by short, grassy vegetation outside of the breeding season, they decreased (P = 0.047) their use of grassy habitats and increased (0.005) their use of cropland. Declines in shrike populations in the southeastern United States as w entire nation, respectively, were correlated (r = 0.83, n = 15, P < 0.001; r = 0.34, n = 113, P < 0 a loss of pastureland suggesting that this habitat may be limiting. Our data suggest that manage resident shrikes in the southeastern United States should include a patchwork of short grassy h sparsely vegetated bare areas at the scale of individual shrike territories.
Effects of habitat structure on patch use by loggerhead shrikes wintering in a natural grassland.
(Condor, 1994) Chavez-Ramirez, Felipe; Gawlik, Dale E.; Prieto, Felipe G.; Slack, R. Douglas
Recent attempts to explain the decline of many Loggerhead Shrike (Lanius ludovicianus) populations (Bystrak and Robbins 1977, Geissler and Noon 198 I, Morrison I98 I) have focused on habitat loss due to modem agricultural practices (Brooks and Temple 1990; Smith and Kruse 1992; Yosefand Grubb 1992,1993; Gawlik and Bildstein 1993). Degree of habitat loss is consistent with the differential declines of shrike populations observed in various regions of the United States. Populations in the intensive agricultural areas of the midwest, south, and southeast are declining more severely than those in the western United States dominated by grasslands (Arbib 1977, Morrison 1981). Although a considerable amount of information exists on shrikes in agricultural systems, none is available regarding habitat changes and the mechanisms affecting shrikes in natural grasslands. Understanding shrike use of natural grasslands can lead to a better understanding of shrike response to land-use changes.
Comparative foraging behavior of sympatric Snow Geese, Greater White-fronted Geese, and Canada Geese during the non-breeding season
(Wilson Bulletin, 1996-03-01) Gawlik, Dale E.; Slack, R. D.
Interspecific comparisons of behavior provide a way to organize information for several species that can lead to hypotheses regarding the functional significance of observed interspecific differences (Clutton-Brock and Harvey 1984). Previous studies of goose time-activity budgets (e.g., Frederick and Klaas 1982, Giroux and Bedard 1990, Black et al. 1991, Ely 1992) have focused on single species and collectively were conducted under widely differing environmental conditions. Certain environmental factors are known to affect goose behavioral patterns and may confound direct interpretation of interspecific comparisons (Table 1). These environmental factors include geographic region, weather, presence of heterospecifics, group size, habitat and vegetation type, year, season, age, social status, and gender. We are aware of no studies that have controlled for environmental variation and examined differences in timebudgets solely as a function of species membership. The objective of this study was to identify interspecies differences (and similarities) in foraging behavior of geese during the non-breeding season, while accounting for sources of environmental variation.
Avian Communities in Bayheads, Willowheads, and Sawgrass Marshes of the Central Everglades
(Wilson Bulletin, 1997-10-03) Rocque, Deborah A.; Gawlik, Dale E.
We compared avian community composition, species richness, and total bird abundance among three vegetation types (bayheads, willowheads and marshes), and between a reduced-hydroperiod and relatively unimpacted landscape in the central Everglades during July-August, 1996. Our results showed that the collective Everglades bird community contained a substantial number of forest birds as well as marsh species. Red-winged Blackbirds (Agelaius phoeniceus), Common Yellowthroats (Geothlypis trichas), and White-eyed Vireos (Vireo griseus) accounted for 65% of total individual birds during the period of study. Wading birds accounted for a relatively small proportion of the total avian community. White-eyed Vireo was the most abundant bird species in bayheads and was closely associated with that habitat. Red-winged Blackbird and Common Yellowthroat were the most abundant species in both willowheads and marsh vegetation. We found no significant difference in bird abundance among vegetation types (P > 0.05) nor between landscapes (P > 0.05). We also found no difference in species richness between landscapes (P > 0.05). A significant (P = 0.02) interaction between vegetation and landscape indicated that species richness differed among vegetation types in the unimpacted landscape, but not in the reduced-hydroperiod landscape. In the unimpacted landscape we detected significantly more species in bayheads than the other two vegetation types (both tests, P ' 0.004). An ordination revealed that in the unimpacted landscape, bird communities were more specific to vegetation types than in the reduced- hydroperiod landscape. Our study demonstrates that two characteristics of a relatively unimpacted landscape in the central Everglades are higher avian species richness and a more distinct avian community in bayheads than in willowheads or marshes. The Everglades restoration process will promote the conservation of avian diversity by restoring the landscape matrix of both marsh and bayhead vegetation.
Long-term Trends in Population and Community Measures of Colonial-nesting Waterbirds in Galveston Bay Estuary
(Colonial Waterbirds, 1998-02-24) Gawlik, Dale E.; Slack, R. Douglas; Thomas, James A.; Harpole, Douglas N.
We examined diversity measures of the colonial-nesting waterbird community in Galveston Bay Estuary from 1973-1990 to determine if trends were apparent at three levels of ecological organization (i.e., community assemblage, and population), each representing a different level of data aggregation. The community was dominated numerically by the Laughing Gull (Larus atricilla), a species with the lowest annual variability. In general, species that exhibited high annual variability also had low mean abundances [e.g., Anhinga (Anhinga anhinga) and Yellow crowned Night-Heron (Nycticorax violaceus)]. White Ibis (Eudocimus albus) and Sandwich Tern (Sterna sandvicensis) were unusual in that they were both highly variable and abundant. Trend analyses of the abundances of individual species showed that Roseate Spoonbill (Ajaia ajaja), Snowy Egret (Egretta thula), and Black Skimmer (Rynchops niger) declined significantly. Neotropical Cormorant (Phalacrocorax brasilianus) and Sandwich Tern increased significantly, and the remaining 13 species showed no statistical change. A classification analysis identified five species assemblages. Two assemblages increased significantly in abundance, one assemblage decreased significantly, and two assemblages showed no change. At the community level, none of the indices we examined showed a significant change over the 18-year period. We hypothesized that loss of coastal marsh vegetation and the development of favorable feeding conditions outside of Galveston Bay may have caused some of the population changes we identified Our ability to identify trends was affected by the level of data aggregation. Community measures were less sensitive to change than were assemblage and population-level data.
Long-term Movement Patterns for Seven Species of Wading Birds
(Waterbirds, 1999-09-08) Melvin, Stefani L.; Gawlik, Dale E.; Scharff, T.
We obtained banding and recovery records from 1914 through 1994 for seven species of wading birds from the Bird Banding Laboratory, United States Geological Survey, Patuxent Wildlife Research Center. We analyzed these data to evaluate differences in dispersal distance and frequency of dispersal movement among species. All records were from birds banded as juveniles and recovered at least five months later between March and July, which is the breeding season in most regions of North America. Focusing on recoveries during the breeding season reduced the chance that movements were related to migration rather than dispersal. When an individual was banded and recovered in the same ten-minute block of latitude and longitude, a movement distance of zero km was recorded. The frequency of zero-distance records provides an indication of breeding site fidelity for each species at a spatial resolution of ten minutes. Our results showed that mean dispersal distance was greatest for the Little Blue Heron (Egretta caerulea; 1148 km) followed by Glossy Ibis (Plegadis falcinellus; 1142 km), Tricolored Heron (Egretta tricolor 1019 km), Great Egret (Casmerodius albus; 909 km), Snowy Egret (Egretta thula; 837 km), Great Blue Heron (Ardea herodias; 758 km), and White Ibis (Eudocimus albus; 545 km). Species which dispersed large distances also exhibited fewer zero-distance records, indicating greater movement frequency. The White Ibis has been classified as a nomad, at one end of a continuum defined by low breeding site-fidelity and several life history traits associated with unpredictable foraging habitat. We found that White Ibises were indeed recovered at new locations the majority (76%) of the time but that the other six species of wading birds we examined were even more likely to move to different sites during subsequent breeding seasons. Movement distance and site fidelity will both likely affect whether a response to habitat restoration is due to immigration or local reproduction. Although an increase in total birds using a restored habitat may be an indication of increased habitat quality, caution should be used in inferring population changes without understanding reproduction, mortality, and movement of individuals using restored habitats.
Avian response to nutrient loading in an oligotrophic wetland
(The Condor, 2002-08-01) Gawlik, Dale E.; Crozier, Gaea E.
We studied the effects of nutrient enrichment on the bird community in an oligotrophic wetland, the Florida Everglades. Among the non-wading birds surveyed in 1996 and 1997, Boat-tailed Grackles (Quiscalus major) and Common Moorhens (Gallinula chloropus) were consistently more abundant in enriched sites, whereas Common Yellowthroats (Geothlypis trichas) were consistently more abundant in unenriched sites. The abundance of Red-winged Blackbird (Agelaius phoeniceus) was not significantly different between enriched and unenriched sites. Among wading birds, Wood Storks (Mycteria americana) and Great Egrets (Ardea alba) were significantly more abundant in enriched than unenriched areas in a dry year, 1991. Great Egrets and all wading species combined were significantly more abundant in enriched than unenriched areas in the wet year, 1995. Great Blue Herons (Ardea herodias) and White Ibises (Eudocimus albus) did not differ in abundance between enriched and unenriched areas in the dry or wet year. A significant interaction between water depth and nutrient status in the wet year indicated that wading bird abundance increased with water depth only in nutrient-enriched areas presumably because the enriched areas had greater food availability than unenriched areas at the same water depth. Bird abundance appeared to increase in nutrient-enriched areas; however, this increase was accompanied by a shift in species composition typically found in the unenriched Everglades and was a fundamental change in the Everglades' distinctive structure.
Distribution of Wading Birds Relative to Vegetation and Water Depths in the Northern Everglades of Florida, USA
(Waterbird Society, 2002-09) Bancroft, Thomas G.; Gawlik, Dale E.; Rutchey, Ken
The Effects of Prey Availability on the Numerical Response of Wading Birds
(The Ecological Society of America, 2002-08) Gawlik, Dale E.
Reduced prey availability has emerged as a primary hypothesis to explain population constraints on wading birds in numerous wetlands around the world. However, there is almost no understanding of which component of prey availability (i.e., prey density or vulnerability of prey to capture) is affecting populations and whether the relative effects of each component differ among species. In this study, I manipulated prey density and water depth (i.e., prey availability) in 12 0.2-ha ponds to determine their relative effects on the numeric response of eight species of free-ranging wading birds (White Ibis, Eu- docimus albus; Wood Stork, Mycteria americana; Snowy Egret, Egretta thula; Glossy Ibis, Plegadis falcinellus; Great Egret, Ardea alba; Tricolored Heron, Egretta tricolor; Great Blue Heron, Ardea herodias; and Little Blue Heron, Egretta caerulea). The experiment was conducted in a constructed wetland adjacent to, and west of, the northern tip of the remnant Everglades, in Palm Beach County, Florida, USA. Each pond was set to a water depth of 10 cm, 19 cm, or 28 cm, and was stocked with golden shiners (Notemigonus crysoleucas) at a density of either 3 fish/m2 or 10 fish/m2. Total bird use (all treatments pooled) increased from day 1 (day after stocking) to day 6, stabilized for several days at -280 birds, and then decreased until day 16, when bird use nearly ceased. Fish were depleted most rapidly in the shallow treatment and least rapidly in the deep treatment. The giving-up-density (GUD) of prey increased with increasing water depth. There was no significant difference among species in the slope of that relationship; however, a visual inspection of the data showed that differences in GUDs were becoming more apparent in the deepest treatment. At that depth, the White Ibis, Wood Stork, and Snowy Egret had higher GUDs than did the Glossy Ibis, Great Egret, Tricolored Heron, Great Blue Heron, and Little Blue Heron. Also, the first three species were affected significantly by both prey density and water depth, whereas the latter five species showed a decidedly weaker response to one or the other component of prey availability. The first three species were more abundant in the shallow treatments and the high prey density treatments, and they abandoned the study site before other species reached their maximum density. The feeding strategy of the first group appeared to be one of searching for new high-quality food patches rather than staying and exploiting food patches that were declining in quality. Species that employed a searching strategy also have shown the most severe population declines, suggesting that factors affecting bird density at feeding sites may also have affected population size.
The use of decoys as a research tool for attracting wading birds
(Association of Field Ornithologists, 2002-03-26) Crozier, Gaea E.
The ability to attract wading birds to a specific location is an important tool for wading bird research. We examined the effectiveness of three commercially available decoy types in attracting free-ranging wading birds to a precise location. There was a statistically significant effect of decoy type on the abundance of wading birds. Wading birds were more attracted to sites with plastic flamingo and Tyvekt bag decoys than with Texas rag decoys or no decoys (control sites). The flamingo and Tyvekt bag decoys have a rigid three-dimensional shape, which may be a more important characteristic than the detailed features of a decoy in attracting wading birds. White wading birds showed a significant effect of decoy type on abundance, whereas birds with dark plumage did not.
An Updated Account of Wading Bird Foraging Behavior
(The Wilson Ornithological Society, 2003-03-01) Kelly, Jay F.; Gawlik, Dale E.; Kieckbusch, David K.
This paper presents an updated account of 34 wading bird foraging behaviors presented by Kushlan (1978a) with findings from later studies for nine wading bird species, including: Great Egret (Ardea alba), Snowy Egret (Egretta thula), Little Blue Heron (Egretta caerulea), Tricolored Heron (Egretta tricolor), Great Blue Heron (Ardea herodias), Green Heron (Butorides virescens), Glossy Ibis (Plegadis falcinellus), White Ibis (Eudocimus albus), and Wood Stork (Mycteria americana). We also include occurrences of the behavior Prey Dropping, which was not described as a foraging behavior in Kushlan (1978a).
Assessing drought-related ecological risk in the Florida Everglades
(Elsevier, 2003-04-28) Pierce, Rachael L.; Gawlik, Dale E.
To determine how habitat structural complexity, which affects prey vulnerability, influences foraging habitat selection by wading birds, a habitat use versus availability study was conducted throughout the Florida Eve glades in 2005 and 2006. Also, an experiment was conducted where structural complexity was manipulated and effect on wading bird foraging efficiency quantified. Among-year differences in habitat selection were found, which corresponded to disparate hydrological conditions. In 2005, a poor hydrological year in terms of the seasonal r cession, wading birds chose foraging sites that had less emergent vegetation, a thicker flocculent layer and higher prey density relative to random sites. In 2006, an optimal hydrological year, wading bird foraging locations we similar to random sites in all aspects. Submerged vegetation did not affect wading bird site selection in either yea The study indicated that hydrological conditions that affect prey density were more important to wading bird foraging success than fine scale variation in habitat characteristics. However, in years of poor hydrology factors that affect prey vulnerability may become increasingly important because the penalty for choosing low quality foraging habitat is greater than in years of more optimal conditions. Elucidating habitat characteristics which create high quality foraging sites will be beneficial in planning wetland restoration projects and gauging future restoration progress. Received 2 October 2009, accepted 18 May 2010.

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