Raptor Environmental

West Chester, OH, United States

Raptor Environmental

West Chester, OH, United States
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Dykstra C.R.,Raptor Environmental | Route W.T.,National Park Service
Journal of Great Lakes Research | Year: 2010

We measured concentrations of DDE, total PCBs, and mercury in bald eagle (Haliaeetus leucocephalus) nestlings at three locations in the upper Midwest: Lake Superior, the upper Mississippi River, and the St. Croix River, 2006-2008. We also analyzed trends in concentrations of these contaminants for eagles on the southern shore of Lake Superior, from 1989 to 2008, using the current and previously published data. Concentrations of DDE in nestling blood plasma samples were greatest on Lake Superior (geometric mean: 16.2 μg/kg, n=29), whereas concentrations of total PCBs were highest in Mississippi River samples (88.6 μg/kg, n=51). Mercury concentrations were highest along the upper St. Croix River (6.81 μg/g wet weight in feathers, n =19). For Lake Superior, DDE concentrations declined significantly in nestling blood plasma samples from 1989 to 2008, an average of 3.0% annually. Similarly, total PCBs in Lake Superior eaglets decreased 4.0% annually from 1989 to 2008, and mercury concentrations in nestling feathers from Lake Superior nests also decreased significantly from 1991 to 2008, 2.4% per year. With the possible exception of mercury on the upper St. Croix River, mean concentrations in 2006. -2008 of all three compounds were below levels associated with significant impairment of reproduction for all sites, and reproductive rates at all three sites averaged >1.2 young per occupied territory, which is greater than the rate indicative of a healthy population. © 2010 Elsevier B.V.

Route W.T.,National Park Service | Dykstra C.R.,Raptor Environmental | Key R.L.,National Park Service | Mathew J.,Wisconsin State Laboratory of Hygiene
Environmental Science and Technology | Year: 2014

We report on patterns and trends in polybrominated diphenyl ethers (PBDEs) in the plasma of 284 bald eagle nestlings sampled between 1995 and 2011 at six study areas in the upper Midwestern United States. Geometric mean concentrations of total PBDEs (ς of nine congeners) ranged from 1.78 ng/mL in the upper St. Croix River watershed to 12.0 ng/mL on the Mississippi River. Lake Superior nestlings fell between these two extremes. Between 2006 and 2011, trends differed among study areas with three declining, two remaining stable, and one increasing. Variation in ςPBDE trends among study areas was linked to trends in individual congeners. The lower brominated PBDEs (BDE-47, -99, and -100) declined 4-10% while the higher brominated congeners (BDE-153 and -154) increased by about 7.0% annually from 2006 to 2011. This increase was the greatest in nestlings from the St. Croix River and below its confluence with the Mississippi River. Region-wide, our data suggest ςPBDEs increased in bald eagle nestlings from 1995 through the mid-2000s and then declined by 5.5% annually from 2006 to 2011. These regional trends are consistent with the removal of penta- and octa-PBDEs from the global market. © 2014 American Chemical Society.

Dykstra C.R.,Raptor Environmental | Simon M.M.,9016 Winthrop Drive | Daniel F.B.,U.S. Environmental Protection Agency | Hays J.L.,Raptor Inc.
Journal of Raptor Research | Year: 2012

Little is known about the habitat and ecology of suburban Barred Owls (Strix varia), a species sometimes considered the nocturnal equivalent of Red-shouldered Hawks (Buteo lineatus). We compared nesting habitat of Barred Owls to that of Red-shouldered Hawks nesting in suburban and urban areas, in and near the city of Cincinnati, Ohio, to determine whether any features distinguished owl nest sites from hawk nest sites. We characterized habitat and land-cover metrics in circular plots of 100 ha and 15 ha, centered on the owl and hawk nests, using ATtiILa software operating within a GIS environment. For the 100-ha plots, the primary cover type in the plots surrounding nests of both species was forest, 41.4 ± 3.4 for Barred Owl plots and 45.9 ± 3.4 for Red-shouldered Hawk plots, followed by low-density residential land: 29.8 ± 4.8 of the Barred Owl plots and 29.3 ± 3.7 of the Red-shouldered Hawk plots. Pasture composed <15 of the plot area for both species and the remainder of the cover types contributed even less. Values of land-cover percentages and metrics did not differ between the species (P > 0.05), for either the large plots or the small (15-ha) plots. Using stepwise binary logit regression analysis, we found that no variables discriminated owl plots from hawk plots. We concluded, based on our methodology, that habitat of suburban Barred Owls differed little from habitat of suburban Red-shouldered Hawks in southwestern Ohio. © 2012 The Raptor Research Foundation, Inc.

Dykstra C.R.,Raptor Environmental | Hays J.L.,Raptor Inc. | Simon M.M.,9016 Winthrop | Wegman A.R.,Cincinnati Museum of Natural History
Wilson Journal of Ornithology | Year: 2012

We examined nestling Red-shouldered Hawks (Buteo lineatus) in 56 nests (147 nestlings) in suburban southwestern Ohio and in 25 nests (67 nestlings) in rural forested Hocking Hills in south-central Ohio, ∼180 km east of southwestern Ohio. Fifteen of 25 nests in Hocking Hills had Protocalliphora avium larvae on one or more nestlings and/or pupae in the nest material. Nineteen nestlings had larvae in one or both ears, an additional 14 had evidence of larvae outside the ears, 32 were not visibly parasitized, and two were not examined or their status was not reported; in contrast, no nests and no nestlings were parasitized in southwestern Ohio. Reproductive rate (young fledged/nest) did not differ between southwestern Ohio and Hocking Hills (2.4 ± 0.1 young/nest at southwestern Ohio vs. 2.7 ± 0.2 at Hocking Hills; P = 0.214). Parasitized nests at Hocking Hills were no more likely to have been used in the previous breeding season than non-parasitized nests (χ2 = 0.903, P = 0.342, n = 22). Similarly, number of young fledged/nest at parasitized nests did not differ from that at non-parasitized nests within Hocking Hills (U = 75.0, P = 1.00, n = 25; mean (± SE) number of young = 2.7 ± 0.3 vs. 2.7 ± 0.3 at parasitized and non-parasitized nests, respectively). The Protocalliphora loads we observed did not appear to have a negative effect on the fledging rate of nestling Red-shouldered Hawks; however, we did not assess any other potential effects of parasitism. © 2012 by the Wilson Ornithological Society.

Dykstra C.R.,Raptor Environmental | Mays Jr. H.L.,Cincinnati Museum Center | Hays J.L.,Raptor Inc. | Simon M.M.,9016 Winthrop Drive | Wegman A.R.,Cincinnati Museum Center
Journal of Raptor Research | Year: 2012

Sexing of raptors is important for understanding their ecology and demography. Males and females of monomorphic species such as Red-shouldered Hawks (Buteo lineatus) may be distinguished using molecular and morphometric techniques. We collected blood samples and morphometric measurements from adult and nestling Red-shouldered Hawks in southern Ohio. We determined sex via amplification of the sex-linked chromo-helicase-DNA-binding gene and polymerase chain reaction. We used a suite of morphometric measurements to generate a recursive partitioning classification tree and in a linear discriminant analysis to determine the sex of adults and nestlings. For adults, the recursive partitioning tree utilized only mass to distinguish sexes, with an overall successful classification rate of 94%. For nestling hawks aged approximately 3 wk and older, mass and toepad (footpad) length were used to distinguish the sexes, with an overall successful classification rate of 91%. The ability to sex adults and nestlings in the field is valuable for studies of dispersal, survival, and behavior. © 2012 The Raptor Research Foundation, Inc.

Penak B.L.,Penak and Associates | Dykstra C.R.,Raptor Environmental | Miller S.J.,Arkansas State University | Bird D.M.,McGill University
Wilson Journal of Ornithology | Year: 2013

Nestling growth may be used to estimate age of nestling raptors, which is valuable for investigating hatch order dynamics and nestling behavior, as well as assessing reproductive rate and back-calculating hatching date. To estimate nestling age, the most valuable parameter to measure growth is one that does not vary greatly with environmental factors, and ideally is applicable over a wide range of populations. We measured growth of nestling Red-shouldered Hawks (Buteo lineatus) in Quebec, Canada, from ages 3 days to near fledging (38 days old), and compared growth of several parameters in different size broods. As a validation study, we measured similar parameters one time in known-age nestling Red-shouldered Hawks in southwestern Ohio. Growth rates for tarsus length, bill length, and tail length differed between nestlings in broods of one and three young, respectively, in Quebec. However, mass gain and growth of secondary feathers (mean length of first and second secondaries) did not differ between brood sizes, although mass gain was more variable than secondary growth. These results suggested that secondary feather length was the most valuable parameter for estimating nestling age in Red-shouldered Hawks. Comparing Ohio nestlings to Quebec nestlings, we found that growth of secondary feathers differed significantly, with Ohio nestlings having smaller secondary length, relative to age estimate. Application of the equation generated with the Quebec data to estimate the age of the Ohio nestlings based on secondary length resulted in estimates that were 2.3 ± 0.3 days (range 0.25-4.5 days; n = 22) younger than the Ohio nestlings' actual ages. Based on this validation study, we suggest that the use of the Quebec age-secondary length equation to estimate age for nestling Red-shouldered Hawks in other parts of eastern North America is acceptable, though with the caveat that such estimates are associated with potential small errors. © 2013 by the Wilson Ornithological Society.

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