Selected vertebrate endangered species of the seacoast of the United States-American peregrine falcon
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FWS/OBS↗
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Responses of Raptorial Birds to Low Level Military Jets and Sonic Booms: Results of the 1980-1981 Joint U.S. Air Force-U.S. Fish and Wildlife Service Study
Summary: For this study, we gathered several kinds of data to determine the likely effects of low level jets and sonic booms on nesting Peregrine Falcons and other raptors. We directly observed responses to worst case stimulus loads: responses to extremely frequent and extremely nearby jet aircraft were often minimal, seldom significant and never associated with reproductive failure. Likewise, responses to real and simulated sonic booms were often minimal and never productivity limiting. In addition to directly observing behavioral responses, in 1981 we invited jet passes at four Prairie Falcon eyries during courtship and incubation when the adults were most likely to abandon, on an ad libitum basis. All four eyries fledged young. Nesting success and site reoccupancy rates were high for all eyries. In tests of two relatively naive captive Peregrine Falcons, we failed to detect significantly negative responses. Typically the birds either quickly resumed feeding or other activities within a few seconds following a pass or boom. The female falcon repeatedly made hunting forays as jets swept overhead. From heart rate (HR) data taken via a telemetering egg during incubation at a wild Prairie Falcon eyrie, we determined that stimulus induced HR alterations were comparable to rate changes of the birds settling to incubate following flight. No significant long term responses were identified. The falcons successfully fledged two young even with the more disruptive activities associated with entering the eyrie three times to position and recover the telemetering eggs. Significantly, birds ofprey of several genera commonly nest in the supersonic military operations areas in southern Arizona. In addition, raptor eyries are frequently found at locations where low level jet traffic naturally concentrates. For example, Prairie Falcon Site 11 is directly on the approach path to strafing and bombing targets. Prairie Falcon Site 1 is in a narrow canyon through which A-10 aircraft naturally funnel while flying low altitude tactical navigation (LATN) missions. Both sites successfully fledged young both years of the study. In summary, while the birds observed for this study were often noticeably alarmed by the subject stimuli, the negative responses were brief and never productivity limiting. In general, the birds were incredibly tolerant of stimulus loads which would likely be unacceptable to humans. It is significant that the endangered species recovery plan for the Peregrine Falcon in the southwest (USFWS 1977) fails to mention military jet operations as a likely factor in the falcon's decrease or that military jet operations should be taken into account in the species recovery.
Book↗
Producing progeny from endangered birds of prey: Treatment of urine-contaminated semen and a novel intramagnal insemination approach
Wild raptors brought into an ex situ environment often have poor semen quality that is further compromised by urine contamination. Generally, it is believed that in birds, artificial insemination into the cloaca or caudal vagina of females requires large doses of high-quality spermatozoa to maximize fertility. In an effort to define and overcome some of the challenges associated with reproduction in wild raptors, the objectives of this study were to 1) evaluate the frequency, impact, and remediation of urine contamination in fresh ejaculates for the purpose of maintaining sperm motility and viability in vitro, and 2) develop a deep insemination method that allows low numbers of washed sperm to be placed directly into the magnum to increase the probability of producing fertilized eggs. The species evaluated include golden eagle (Aquila chrysoetos), imperial eagle (A. adalberti), Bonelli's eagle (Hiernaetus fasciatus), and peregrine, falcon (Falco peregrinus). Semen samples were collected and pooled by species, and a minimum of 25 pooled ejaculates per species were evaluated for urine contamination, pH, sperm viability, and sperm motility; the samples were either unwashed or washed in neutral (pH 7.0) or alkaline (pH 8.0) modified Lake's diluent. Female golden eagles and peregrine falcons were inseminated via transjunctional, intramagnal insemination with washed spermatozoa from urine-contaminated samples. Urine contamination occurred in 36.8 +/- 12.8% (mean +/- SEM) golden eagle, 43.1 +/- 9.1% imperial eagle, 28.7 +/- 16.1% Bonelli's eagle, and 48.2 +/- 17.3% peregrine falcon ejaculates. The pH in urine-contaminated semen samples ranged from 6.48 +/- 0.3 to 6.86 +/- 0.2, and in noncontaminated samples it ranged from from 7.17 +/- 0.1 to 7.56 +/- 0.1. Sperm viability and motility were reduced (P < 0.05) in all species for unwashed vs. washed sperm after 30 min incubation at room temperature. Two peregrine falcon chicks and one golden eagle chick hatched after intramagnal insemination. This study demonstrates that urine contamination, a common and lethal acidifier in manually collected raptor ejaculates, can be circumvented by immediate, gentle seminal washing. Furthermore, these processed sperm, when deposited by transjunctional intramagnal insemination, can produce live young.
Journal of Zoo and Wildlife Medicine↗
Raptor responses to low-level jet aircraft and sonic booms
We estimated effects of low-level military jet aircraft and mid- to high-altitude sonic booms (actual and simulated) on nesting peregrine falcons ( Falco peregrinus ) and seven other raptors by observing their responses to test stimuli, determining nesting success for the test year, and evaluating site reoccupancy rates for the year following the tests. Frequent and nearby jet aircraft passes: (1) sometimes noticeably alarmed birds, (2) occasionally caused birds to fly from perches or eyries, (3) most often evoked only minimal responses, and (4) were never associated with reproductive failure. Similarly, responses to real and simulated mid- to high-altitude sonic booms were often minimal and never appeared productivity limiting. Eighteen (95%) of 19 nest sites subjected to low-level jet flights and/or simulated sonic booms in 1980 fledged young during that year. Eighteen (95%) of 19 sites disturbed in 1980 were reoccupied by pairs or lone birds of the same species in 1981. We subjected four pairs of prairie falcons ( Falco mexicanus ) to low-level aircraft at ad libitum levels during the courtship and incubation phases when adults were most likely to abandon: all four eyries fledged young. From heart rate (HR) data taken via a telemetering egg at another prairie falcon eyrie, we determined that stimulus-induced HR alterations were comparable to rate changes for birds settling to incubate following flight. While encouraging, our findings cannot be taken as conclusive evidence that jet flights and/or sonic booms will have no long-term negative effects for other raptor species or for other areas. In addition, we did not experiment with totally naive wild adults, rotary-winged aircraft, or low-level sonic booms.
Environmental Pollution↗
What is Falco Altaicus Menzbier?
The systematics of the Altay falcon (Falco altaicus/lorenzi) remains enigmatic. First reported in 1811, it has been treated as a gyrfalcon (F. rusticolus), a saker (F. cherrug), and two separate species (F. lorenzi and F. altaicus). Of 53 'altaicus' specimens examined, at least two are misidentified gyrfalcons, many are typical sakers, but 34 (the core group) are considered to be the true Altay falcon type. Adults have red, brown, and gray color morphs. The red (backed) morph closely resembles some eastern sakers; the chocolate and gray morphs resemble respective gyrfalcon morphs. While the true affinities of the Altay falcon will be resolved by molecular genetics, the ecological, geographical, and morphological information suggest that the core group represents a gyrfalcon-saker cross that is being swamped through back crosses with the saker. The breeding range of the core group (i.e., the Altay and Sayan Mountains) is much smaller than previously reported.
Journal of Raptor Research↗
Conservation committee report. Falconry: Effects on raptor populations and management in North America
The art of falconry in North America, practiced by a few individuals for many years, attracted little attention until the 1960?s. Presently about 2800 falconers are licensed in the United States with less than one half considered to be active. While interest in this art is expected to increase, we believe growth will be slow, probably 5 to 10% per year, due to rigorous demands on time and equipment required and restrictive regulations.....Many different species of raptors have been used in falconry. Presently 6 species are commonly used, especially the Red-tailed Hawk and American Kestrel. Present evidence suggests that only 2 races of the Peregrine Falcon are threatened in North America, and declines may have occurred in local populations of other species. Declines in populations of Peregrines are attributed to pesticide contamination of food chains. Apparent declines in other populations of raptors are also attributed to pesticides and locally to changes in land use and possibly indiscriminate shooting. Removal of raptors from wild populations for falconry has not had documentable adverse effects except possibly at local nesting sites. Continuation of the art of falconry under the framework of the recent federal regulations is not expected to have measurable impacts on region-wide populations. Management of raptors is poorly developed and relatively unexplored. Captive breeding of raptors holds much promise for production of birds both for re-establishment and as a source of birds for falconry. Falconers have contributed much to the continued improvement of the Cornell University Peregrine program in terms of breeding stocks and technique development.
The Wilson Bulletin↗
Feather mercury concentrations in North American raptors sampled at migration monitoring stations
We assessed total mercury (THg) concentrations in breast feathers of diurnal North American raptors collected at migration monitoring stations. For 9 species in the Pacific Flyway, we found species and age influenced feather THg concentrations whereas sex did not. Feather THg concentrations µg/g dry weight (dw) averaged (least-squared mean±standard error) higher for raptors that generally consume >75% avian prey (sharp-shinned hawk Accipiter striatus: n=113; 4.35±0.45 µg/g dw, peregrine falcon Falco peregrinus: n=12; 3.93±1.11 µg/g dw, Cooper’s hawk Accipiter cooperii: n=20; 2.35±0.50 µg/g dw, and merlin Falco columbarius: n=59; 1.75±0.28 µg/g dw) than for raptors that generally consume <75% avian prey (northern harrier Circus hudsonius: n=112; 0.75±0.10 µg/g dw, red-tailed hawk Buteo jamaicensis: n=109; 0.56±0.06 µg/g dw, American kestrel Falco sparverius: n=16; 0.57±0.14 µg/g dw, prairie falcon Falco mexicanus: n=10; 0.41±0.13 µg/g dw) except for red-shouldered hawks Buteo lineatus: n=10; 1.94±0.61 µg/g dw. Feather THg concentrations spanning 13-years (2002-2014) in the Pacific Flyway differed among 3 species, where THg increased for juvenile northern harrier, decreased for adult red-tailed hawk, and showed no trend for adult sharp-shinned hawk. Mean feather THg concentrations in juvenile merlin were greater in the Mississippi Flyway (n=56; 2.14±0.18 µg/g dw) than those in the Pacific Flyway (n=49; 1.15±0.11 µg/g dw) and Intermountain Flyway (n=23; 1.14±0.16 µg/g dw), and Atlantic Flyway (n=38; 1.75±0.19 µg/g dw) averaged greater than the Pacific Flyway. Our results indicate that raptor migration monitoring stations provide a cost-effective sampling opportunity for biomonitoring environmental contaminants within and between distinct migration corridors and across time.
Ecotoxicology↗
Modelling interactions of toxicants and density dependence in wildlife populations
1. A major challenge in the conservation of threatened and endangered species is to predict population decline and design appropriate recovery measures. However, anthropogenic impacts on wildlife populations are notoriously difficult to predict due to potentially nonlinear responses and interactions with natural ecological processes like density dependence. 2. Here, we incorporated both density dependence and anthropogenic stressors in a stage-based matrix population model and parameterized it for a density-dependent population of peregrine falcons Falco peregrinus exposed to two anthropogenic toxicants [dichlorodiphenyldichloroethylene (DDE) and polybrominated diphenyl ethers (PBDEs)]. Log-logistic exposure–response relationships were used to translate toxicant concentrations in peregrine falcon eggs to effects on fecundity. Density dependence was modelled as the probability of a nonbreeding bird acquiring a breeding territory as a function of the current number of breeders. 3. The equilibrium size of the population, as represented by the number of breeders, responded nonlinearly to increasing toxicant concentrations, showing a gradual decrease followed by a relatively steep decline. Initially, toxicant-induced reductions in population size were mitigated by an alleviation of the density limitation, that is, an increasing probability of territory acquisition. Once population density was no longer limiting, the toxicant impacts were no longer buffered by an increasing proportion of nonbreeders shifting to the breeding stage, resulting in a strong decrease in the equilibrium number of breeders. 4. Median critical exposure concentrations, that is, median toxicant concentrations in eggs corresponding with an equilibrium population size of zero, were 33 and 46 μg g −1 fresh weight for DDE and PBDEs, respectively. 5. Synthesis and applications. Our modelling results showed that particular life stages of a density-limited population may be relatively insensitive to toxicant impacts until a critical threshold is crossed. In our study population, toxicant-induced changes were observed in the equilibrium number of nonbreeding rather than breeding birds, suggesting that monitoring efforts including both life stages are needed to timely detect population declines. Further, by combining quantitative exposure–response relationships with a wildlife demographic model, we provided a method to quantify critical toxicant thresholds for wildlife population persistence.
California↗
Recent trends in counts of migrant hawks from northeastern North America
Using simple regression, pooled-sites route-regression, and nonparametric rank-trend analyses, we evaluated trends in counts of hawks migrating past 6 eastern hawk lookouts from 1972 to 1987. The indexing variable was the total count for a season. Bald eagle ( Haliaeetus leucocephalus ), peregrine falcon ( Falco peregrinus ), merlin ( F. columbarius ), osprey ( Pandion haliaetus ), and Cooper's hawk ( Accipiter cooperii ) counts increased using route-regression and nonparametric methods (P < 0.05). Northern harrier ( Circus cyaneus ) counts increased based on the nonparametric method (P < 0.01) but not the route-regression method (P > 0.10). We found no consistent trends (P > 0.10) in counts of sharp-shinned hawks ( A. striatus ), northern goshawks ( A. gentilis ) red-shouldered hawks ( Buteo lineatus) , red-tailed hawks ( B. jamaicensis ), rough-legged hawsk ( B. lagopus ), and American kestrels ( F. sparverius ). Broad-winged hawk ( B. platypterus ) counts declined (P < 0.05) based on the route-regression method. Empirical comparisons of our results with those for well-studied species such as the peregrine falcon, bald eagle, and osprey indicated agreement with nesting surveys. We suggest that counts of migrant hawks are a useful and economical method for detecting long-term trends in species across regions, particularly for species that otherwise cannot be easily surveyed.
Michigan, Minnesota, New Jersey, New York, Pennsyl↗
Reconnaissance investigation of water-quality, bottom sediment, and biota associated with irrigation drainage in the Lower Rio Grande Valley and Laguna Atascosa National Wildlife Refuge, Texas, 1986-87
In 1986, the Department of the Interior conducted reconnaissance investigations in nine areas of the western conterminous United States to determine whether irrigation drainage has caused or has the potential to cause harmful effects to human health, fish, and wildlife, or may adversely affect the suitability of water for beneficial uses. Data collected in the lower Rio Grande valley and Laguna Atascosa National Wildlife Refuge reconnaissance investigation indicate that concentrations of dissolved minor elements in water are small. The maximum dissolved concentrations of arsenic, cadmium, mercury, chromium, selenium, and zinc exceed the 75th-percentile baseline values developed for the study; however, maximum dissolved concentrations of cadmium, mercury, and selenium exceeded the 75th-percentile baseline values by 1 microgram per liter or less. Concentrations of dissolved boron increased significantly from west to east. The smallest concentration of dissolved boron, 220 micrograms per liter, was detected in International Falcon Reservoir. The largest concentration of dissolved boron, 11,000 micrograms per liter, was detected on the refuge in Athel Pond. No chlorophenoxy herbicides were detected in water during the June 1986 sampling. Simazine, prometone, and atrazine were the only triazine herbicides detected, and concentrations of these herbicides did not exceed 0.8 microgram per liter. DDE, the only organochlorine Insecticide detected in water, was detected at two locations at concentrations of 0.01 micrograms per liter. Methyl parathion, malathion, and diazinon were the only organophosphorus compounds detected in the June 1986 sampling, and the maximum concentrations of these compounds were 0.75, 0.71, and 0.26 micrograms per liter, respectively. The analysis of three samples collected in August 1986 indicate that the types of pesticides collected during runoff were similiar to those detected during the June 1986 sampling. The exception was that the herbicide 2,4-D was detected during runoff. Concentrations of dissolved cadmium exceeded the chronic criteria for freshwater aquatic life in the Cayo Atascoso in the Laguna Atascosa National Wildlife Refuge. Chromium exceeded the acute and chronic freshwater criteria at four locations in the refuge and in the Laguna Madre. Chromium also exceeded the chronic saltwater criteria in Athel Pond. Concentrations of dissolved copper exceeded the acute and chronic criteria for saltwater aquatic life at 13 locations. Mercury exceeded the chronic criteria for freshwater and saltwater aquatic life at three locations, and dissolved nickel concentrations exceeded the chronic criteria for saltwater aquatic life in the Rio Grande at Anzalduas Dam and in the Resaca de los Frenos near Russeltown. No organophosphorus insecticides, polychlorinated napthalenes, or polychlorinated biphenyl compounds were detected in four bed-sediment samples. DDE, an organochlorine insecticide, was detected in all four samples at concentrations ranging from 0.2 to 34 micrograms per kilogram. Chlordane, ODD, DDE, DOT, and dieldrin were all detected in the Resaca de los Fresnos at U.S. Highway 77 at San Benito with concentrations of 4.0, 9.7, 9.3, 7.3, and 0.1 micrograms per kilogram, respectively. Data collected by U.S. Fish and Wildlife Service in 1985 indicate that DDE was detected in approximately 75 percent of the bed sediment samples analyzed. The maximum concentration detected in that study was 6.0 micrograms per gram; the median concentration was 0.01 micrograms per gram. Minor-element data from 22 fish samples indicate that the maximum concentrations of arsenic, copper, mercury, selenium, and zinc exceeded the 85thpercentile baseline concentrations established by the U.S. Fish and Wildlife Service for the National Contaminant Biomonitoring Program. None of the median concentrations of these minor elements exceeded the baseline concentrations. The maximum concentrations of aluminum, barium, iron, manganese, and tin were detected in fish collected from International Falcon Reservoir. This reservoir stratifies in the summer, and minor elements may be released from the bed sediments in the deep parts of the reservoir and incorporated into the food chain. Toxaphene was detected in 11 fish samples; detectable concentrations ranged from 0.98 to 5.1 micrograms per gram, wet weight. DOT also was detected in 11 fish samples with concentrations ranging from 0.021 to 0.066 micrograms per gram, wet weight. ODD was detected in 21 fish samples; concentrations ranged from 0.015 to 0.16 micrograms per gram, wet weight. DDE was detected in all 22 fish samples, and concentrations ranged from 0.36 to 9.9 micrograms per gram, wet weight. The maximum concentrations of DOT and ODD exceeded the 1980-81 baseline concentrations. The median and maximum concentrations of toxaphene and DDE exceeded the 1980-81 baseline concentrations. The largest concentrations of toxaphene, ODD, and DDE in fish were all measured in samples collected at the Main Floodway near Progreso.
Texas↗
Preening behavior of adult gyrfalcons tagged with backpack transmitters
Radio transmitters provide data that enhance understanding of raptor biology (Walls and Kenward 2007) and are now used to answer a multitude of research questions (Meyburg and Fuller 2007). However, transmitters affect the birds that carry them (Barron et al. 2010), and it is important to document and evaluate such effects (Casper 2009). For example, decreased survival has been documented in Prairie Falcons (Falco mexicanus; Steenhof et al. 2006), Northern Goshawks (Accipiter gentilis; Reynolds et al. 2004), and Spotted Owls (Strix occidentalis; Paton et al. 1991) tagged with radio transmitters. However, no such effects were reported for Peregrine Falcons (Falco peregrinus; Fuller et al. 1998, McGrady et al. 2002) and a number of other species (Kenward 2001). White and Garrott (1990) noted that in general, animals tagged with radio transmitters often altered their behaviors for 1–14 d after release during an adjustment period that included increased preening and grooming frequencies. Although more than 90 Gyrfalcons (Falco rusticolus) have been tagged with radio transmitters (e.g., Burnham 2007, McIntyre et al. 2009, T. Booms unpubl. data), the effects of transmitters on this species are not well documented. Anecdotal information suggests some Gyrfalcons might be negatively affected by radio-tagging (Booms et al. 2008). As part of a study investigating Gyrfalcon breeding biology, we conducted opportunistic, focused observations on two radio-tagged adult female Gyrfalcons and their unmarked mates. We here describe and quantify preening behavior of Gyrfalcons shortly after radio-tagging.
Journal of Raptor Research↗
Short-term effects of oil ingestion on American kestrels (Falco sparverius)
The Mexican Ixtoc oil well blowout resulted in extensive oil contamination along the Texas Gulf coast. This oil posed a potential hazard to migrating birds including the endangered peregrine falcon (Falco peregrinus). Laboratory tests with the American kestrel (Falco sparverius) indicated that the oil: water mixture gathered at the surface of the blowout site posed little acute hazard to falcons.
Journal of Wildlife Diseases↗
Predatory bird populations in the east Mojave Desert, California
We surveyed 7 species of predatory birds weekly during a 12-month period (December 1992 through November 1993) in the east Mojave Desert, California. The Common Raven (Corvus corax) was the most frequently observed species with an average of 6.9 sightings per 100 km. Turkey Vultures (Cathartes aura), Red-tailed Hawks (Buteo jamaicensis), Loggerhead Shrikes (Lanius ludovicianus), American Kestrels (Falco sparverius), Golden Eagles (Aquila chrysaetos), and Prairie Falcons (Falco mexicanus) were seen in decreasing order of frequency of observation through the study period. Ravens, Red-tailed Hawks, Loggerhead Shrikes, American Kestrels, and Prairie Falcons were seen throughout the year. Turkey Vultures were not present during winter months, while Golden Eagles were seen only during November and December. Turkey Vultures, Red-tailed Hawks, and ravens were most numerous on agricultural lands, while Loggerhead Shrikes were most Common at urban areas. Raven numbers increased with increasing number of linear rights-of-way parallel to the survey route. Perching was the most common behavior type, although Turkey Vultures and ravens were often observed soaring, flying, or standing on the ground near highways. Transmission powerline towers and telephone poles were used as perch sites disproportionately to availability.
Great Basin Naturalist↗
Winter habitat associations of diurnal raptors in Californias Central Valley
The wintering raptors of California's Central Valley are abundant and diverse. Despite this, little information exists on the habitats used by these birds in winter. We recorded diurnal raptors along 19 roadside survey routes throughout the Central Valley for three consecutive winters between 2007 and 2010. We obtained data sufficient to determine significant positive and negative habitat associations for the White-tailed Kite (Elanus leucurus), Bald Eagle {Haliaeetus leucocephalus), Northern Harrier (Circus cyaneus), Red-tailed Hawk (Buteo jamaicensis), Ferruginous Hawk (Buteo regalis), Rough-legged Hawk (Buteo lagopus), American Kestrel (Falco sparverius), and Prairie Falcon (Falco mexicanus). The Prairie Falcon and Ferruginous and Rough-legged hawks showed expected strong positive associations with grasslands. The Bald Eagle and Northern Harrier were positively associated not only with wetlands but also with rice. The strongest positive association for the White-tailed Kite was with wetlands. The Red-tailed Hawk was positively associated with a variety of habitat types but most strongly with wetlands and rice. The American Kestrel, Northern Harrier, and White-tailed Kite were positively associated with alfalfa. Nearly all species were negatively associated with urbanized landscapes, orchards, and other intensive forms of agriculture. The White-tailed Kite, Northern Harrier, Redtailed Hawk, Ferruginous Hawk, and American Kestrel showed significant negative associations with oak savanna. Given the rapid conversion of the Central Valley to urban and intensive agricultural uses over the past few decades, these results have important implications for conservation of these wintering raptors in this region.
Western Birds↗
Demographic and potential biological removal models identify raptor species sensitive to current and future wind energy
A central challenge in applied ecology is understanding the effect of anthropogenic fatalities on wildlife populations and predicting which populations may be particularly vulnerable and in greatest need of management attention. We used 3 approaches to investigate potential effects of fatalities from collisions with wind turbines on 14 raptor species for both current (106 GW) and anticipated future (241 GW) levels of installed wind energy capacity in the United States. Our goals were to identify species at relatively high vs low risk of experiencing population declines from turbine collisions and to also compare results generated from these approaches. Two of the approaches used a calculated turbine-caused mortality rate to decrement population growth, where population trends were derived either from the North American Breeding Bird Survey or a matrix model parameterized from literature-derived demographic values. The third approach was potential biological removal, which estimates the number of fatalities that allow a population to reach and maintain its optimal sustainable population set by management concerns. Different results among the methods reveal substantial gaps in knowledge and uncertainty in both demographic parameters and species-specific estimates of fatalities from wind turbines. Our results suggest that, of the 14 species studied, those with relatively higher potential of population-level impacts from wind turbine collisions included barn owl, ferruginous hawk, golden eagle, American kestrel, and red-tailed hawk. Burrowing owl, Cooper’s hawk, great horned owl, northern harrier, turkey vulture, and osprey had a relatively lower potential for population impacts, and results were not easily interpretable for merlin, prairie falcon, and Swainson’s hawk. Projections of current levels of fatalities to future wind energy scenarios at 241 GW of installed capacity suggest some species could experience population declines because of turbine collisions. Populations of those species may benefit from research to identify tools to prevent or reduce raptor collisions with wind turbines.
Ecosphere↗
Transboundary pollution: Persistent organochlorine pesticides in migrant birds of the Southwestern United States and Mexico
The hypothesis that migratory birds accumulate persistent organochlorine pesticides (POPs) during the winter in Latin America has been prevalent for many years, particularly since 1,1,1-trichloro-2,2–bis(p-chlorophenyl)ethane (DDT) was banned in the United States in 1972. It has been suggested that peregrine falcons ( Falco peregrinus ), black-crowned night herons ( Nycticorax nycticorax ), white-faced ibises ( Plegadis chihi ), various migratory waterfowl and shorebirds, and other avian species accumulate higher concentrations of POPs while on migration or on their wintering grounds in Latin America. Nonetheless, the data obtained thus far are limited, and there is no clear pattern to suggest that such accumulation occurs on a widespread basis. In this review wildlife contaminant studies conducted along the U.S.-Mexico border and throughout Mexico are discussed. The results for the most part seem to indicate that no major accumulation of 2,2-bis(p-chlorophenyl)-1,1-dichloroethylene) (DDE), the most persistent organochlorine compound, has occurred or been reported for most parts of Mexico. The majority of the DDE values in birds from Mexico were similar to those reported in birds from the southwestern United States during the same years. More work needs to be done, particularly in those cotton-producing areas of Mexico where DDT was applied heavily in the past (e.g., Chiapas and Michoacan). Because DDT is still used for malaria control and may still be used in agriculture in Chiapas, this state is probably the one where most migrant species would still be at a significant risk of increased accumulation of DDE and DDT.
Environmental Toxicology and Chemistry↗
Environmental contaminants in Texas, USA, wetland reptiles: Evaluation using blood samples
Four species of reptiles (diamondback water snake [ Nerodia rhombifer ], blotched water snake [ N. erythrogaster ], cottonmouth [ Agkistrodon piscivorus ], and red-eared slider [ Trachemys scripta ]) were collected at two contaminated and three reference sites in Texas, USA. Old River Slough has received intensive applications of agricultural chemicals since the 1950s. Municipal Lake received industrial arsenic wastes continuously from 1940 to 1993. Blood samples were analyzed for organochlorines, potentially toxic elements, genetic damage, and plasma cholinesterase (ChE). Dichlorodiphenyldichloroethylene (DDE) concentrations reached as high as 3.0 ppm (wet weight) in whole blood of a diamondback water snake at Old River Slough, a level probably roughly equivalent to the maximum concentration found in plasma of peregrine falcons ( Falco peregrinus ) in 1978 to 1979 when DDE peaked in this sensitive species. Possible impacts on diamondback water snakes are unknown, but at least one diamondback water snake was gravid when captured, indicating active reproduction. Arsenic was not found in red-eared sliders (only species sampled) from Municipal Lake. Red-eared sliders of both sexes at Old River Slough showed declining levels of ChE with increasing mass, suggesting a life-long decrease of ChE levels. Possible negative population consequences are unknown, but no evidence was found in body condition (mass relative to carapace length) that red-eared sliders at either contaminated site were harmed.
Texas↗
Estimating raptor nesting success: old and new approaches
Studies of nesting success can be valuable in assessing the status of raptor populations, but differing monitoring protocols can present unique challenges when comparing populations of different species across time or geographic areas. We used large datasets from long-term studies of 3 raptor species to compare estimates of apparent nest success (ANS, the ratio of successful to total number of nesting attempts), Mayfield nesting success, and the logistic-exposure model of nest survival. Golden eagles (Aquila chrysaetos), prairie falcons (Falco mexicanus), and American kestrels (F. sparverius) differ in their breeding biology and the methods often used to monitor their reproduction. Mayfield and logistic-exposure models generated similar estimates of nesting success with similar levels of precision. Apparent nest success overestimated nesting success and was particularly sensitive to inclusion of nesting attempts discovered late in the nesting season. Thus, the ANS estimator is inappropriate when exact point estimates are required, especially when most raptor pairs cannot be located before or soon after laying eggs. However, ANS may be sufficient to assess long-term trends of species in which nesting attempts are highly detectable.
Journal of Wildlife Management↗