37 research outputs found
Effects of low level military training flights on wading bird colonies in Florida
During 1983 and 1984 the effect of low level military training
flights on the establishment. size and reproductive success of wading
bird colonies was studied in Florida. Based on the indirect evidence
of colony distributions and turnover rates in relation to military
areas (training routes designated to 500 feet or less above ground
level and military operations areas). there was no demonstrated effect
of military activity on wading bird colony establishment or size on a
statewide basis. Colony distributions were random with respect to
military areas and turnover rates were within 2% when military and
non-military areas were compared. Colony distributions and turnover
rates, however. were related to the amount and type.Les tuer-tne or
freshwater) of wetland. respectively.
During two breeding seasons the behavioral responses and
reproductive success of selected species were monitored in a
non-habituated treatment colony (military overflights) and a control
colony (no overflights). Breeding wading birds responded to F-16
overflights at 420 knots indicated airspeed. 82-84% maximum rpm. 500
feet above ground level and sound levels ranging from 55-100 dBA by
exhibiting no response. looking up or changing position (usually to an
alert posture): no productivity limiting responses were observed.
High-nesting Great Egrets responded more than other species, nestling
Great Egrets and Cattle Egrets responded significantly (r <.05) more
intensely than adults of their respective species, and adults
responded less during incubation and late chick-rearing than at other
times. In addition, no differences in adult attendance, aggressive
interactions or chick feeding rates were observed to result from F-16 overflights. No evidence of habituation to overflights was noted.
Humans entering the colony or airboats approaching the colony vicinity
elicited the most severe responses (flushing and panic flights)
observed at both sites.
Since relatively little coastal military activity occurs at low
levels ( ~500 ft) and only one Brown Pelican colony (5-6% of the
breeding population) was located in such an area, the reproductive
success of five, more lIexposedll study species (Great Egrets, Snowy
Egrets, Tricolored Herons, Little Blue Herons, Cattle Egrets) nesting
in interior freshwater colonies was studied. Reproductive activity
including such factors as nest success, nestling survival, nestling
mortality, and nesting chronology was independent of F-16 overflights
but related to ecological factors including colony location, colony
characteristics and climatology. The responses to and effects of F-16
overflights, as reported here, should not be considered representative
of military aircraft at lower altitudes or greater noise levels. (194 pages
Spatial and Temporal Variability in Nest Success of Snail Kites in Florida : A Meta-Analysis
Nesting success of Snail Kites (Rostrhamus sociabilis) in Florida is highly variable among years and locations, and hydrology is the most frequently reported explanatory factor. We conducted a meta-analysis to evaluate the extent of spatial and temporal variability in nesting success, and explicitly tested for the effects of annual minimum water levels. Data were obtained from six independent studies spanning 22 years and 11 wetlands. Our results indicated there was substantial spatial and temporal variability in nest success and that annual minimum water level, either as a categorical or continuous response, was not a significant source of this variation. Our results do not imply that low water levels do not influence nest success. Rather, they indicate that the number of nests affected by low water conditions was quite low
Snail Kite Nest Success and Water Levels : A Reply to Beissinger and Snyder
Beissinger and Snyder present a commentary on our recent paper on spatial and temporal variability in nest success of Snail Kites (Rostrhamus sociabilis) in Florida (Dreitz et al. 2001). Beissinger and Snyder reanalyze a subset of data presented in our original paper to show that water levels have a significant influence on nest success. To make their argument, the authors conduct separate analyses for 5 of the original 11 wetlands; including only those having the most data. We agree with Beissinger and Snyder that water levels can affect nest success in some areas or years, as we stated in Dreitz et al. (2001). However, the purpose of our original paper was to examine the influences of nest success over broad spatial and temporal scales. When viewed in this context, using a meta-analysis, water levels alone explain only a small amount of the observed variation in nest success. One of the advantages of using a meta-analysis is that it uses all of the available data to provide an indication of the overall magnitude of an effect, which can easily be misinterpreted when viewed in a narrower context of individual study sites. We discuss the management implication of these alternative perspectives on water levels in light of their effect on habitat quality and persistence
Climate Change Education for Nevada
42 PowerPoint slides Session 1: Education Convener: David Hassenzahl, UNLV Abstract: -Five Year Strategic Plan -Goal 6 - Create a scholarly environment to promote research skills and intellectual development for Nevada educators and students (K-12, undergraduate undergraduate, and graduate) -Primary Strategy - Develop educational infrastructure to train students at all levels and provide public outreach in climate change issue
Food consumption and growth energetics of nestling golden eagles
Ph.D.EcologyUniversity of Michiganhttp://deepblue.lib.umich.edu/bitstream/2027.42/158077/1/8106119.pd
A Comparison of Direct Observations and Collections of Prey Remains in Determining the Diet of Golden Eagles
Two techniques were used to determine the diets of 4 pairs of nesting golden eagles (Aquila chrysaetos) in southwestern Idaho during 1978 and 1979; direct observations of prey deliveries to nests were compared with estimates of food habits derived from analyses of systematic collections of pellet and prey remains. There was no difference (P \u3e 0.05) between the 2 methods in the estimated species composition, either by percent frequency or percent biomass. Comparisons of the daily capture rates derived using the 2 techniques demonstrated that collections of pellet and prey remains consistently underestimated observed prey delivery. Estimates of the time period collections reflected prey deliveries ranged from 1.6 to 5.5 days, but were consistent for each nest. Periodic observations of food delivery at nest sites can be used to correct for prey biomass unaccounted for in the collections; this procedure would enable researchers to use collections of pellet and prey remains to estimate prey biomass delivered to nests