Inhibition of brain cholinesterase activity in forest birds and squirrels exposed to aerially applied acephate
No abstract available.
Bulletin of Environmental Contamination and Toxico↗
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Bird use and heavy metal accumulation in waterbirds at dredge disposal impoundments, Corpus Christi, Texas
No abstract available.
Texas↗
The occurrence of lead in tissues of wild birds
No abstract available.
Bulletin of Environmental Contamination and Toxico↗
Effects of No. 2 fuel oil on hatchability of marine and estuarine bird eggs
Eggs of Louisiana herons, sandwich terns, and laughing gulls were oiled with either 0, 5, or 20 μl of No. 2 fuel oil in the field and in the laboratory. After 5 days of natural incubation, field-oiled and control eggs were opened and embryonic mortality was determined. No. 2 fuel oil produce'd 61% mortality in Louisiana heron eggs, 56% in sandwich tern eggs, and 83% in laughing gull eggs. Hatching success of artificially incubated, oiled eggs appeared to be lower than in control eggs. However, stress during shipment to the laboratory and problems within the incubator probably contributed to reduced hatchability in both groups.
Bulletin of Environmental Contamination and Toxico↗
A comparison of the teratogenicity of methylmercury and selenomethionine injected into bird eggs
Methylmercury chloride and seleno-L-methionine were injected separately or in combinations into the fertile eggs of mallards (Anas platyrhynchos), chickens (Gallus gallus), and double-crested cormorants (Phalacrocorax auritus), and the incidence and types of teratogenic effects were recorded. For all three species,selenomethionine alone caused more deformities than did methylmercury alone. When mallard eggs were injected with the lowest dose of selenium (Se) alone (0.1 μg/g), 28 of 44 embryos and hatchlings were deformed, whereas when eggs were injected with the lowest dose of mercury (Hg) alone (0.2 μg/g), only 1 of 56 embryos or hatchlings was deformed. Mallard embryos seemed to be more sensitive to the teratogenic effects of Se than chicken embryos:0 of 15 chicken embryos or hatchlings from eggs injected with 0.1 μg/g Se exhibited deformities. Sample sizes were small with double-crested cormorant eggs, but they also seemed to be less sensitive to the teratogenic effects of Se than mallard eggs. There were no obvious differences among species regarding Hg-induced deformities. Overall, few interactions were apparent between methylmercury and selenomethionine with respect to the types of deformities observed. However, the deformities spina bifida and craniorachischisis were observed only when Hg and Se were injected in combination. One paradoxical finding was that some doses of methylmercury seemed to counteract the negative effect selenomethionine had on hatching of eggs while at the same time enhancing the negative effect selenomethionine had on creating deformities. When either methylmercury or selenomethionine is injected into avian eggs, deformities start to occur at much lower concentrations than when the Hg or Se is deposited naturally in the egg by the mother.
Archives of Environmental Contamination and Toxico↗
Phenological adjustment in arctic bird species: relative importance of snow melt and ecological factors
Previous studies have documented advancement in clutch initiation dates (CIDs) in response to climate change, most notably for temperate-breeding passerines. Despite accelerated climate change in the Arctic, few studies have examined nest phenology shifts in arctic breeding species. We investigated whether CIDs have advanced for the most abundant breeding shorebird and passerine species at a long-term monitoring site in arctic Alaska. We pooled data from three additional nearby sites to determine the explanatory power of snow melt and ecological variables (predator abundance, green-up) on changes in breeding phenology. As predicted, all species (semipalmated sandpiper, Calidris pusilla , pectoral sandpiper, Calidris melanotos , red-necked phalarope, Phalaropus lobatus , red phalarope, Phalaropus fulicarius , Lapland longspur, Calcarius lapponicus ) exhibited advanced CIDs ranging from 0.40 to 0.80 days/year over 9 years. Timing of snow melt was the most important variable in explaining clutch initiation advancement (“climate/snow hypothesis”) for four of the five species, while green-up was a much less important explanatory factor. We found no evidence that high predator abundances led to earlier laying dates (“predator/re-nest hypothesis”). Our results support previous arctic studies in that climate change in the cryosphere will have a strong impact on nesting phenology although factors explaining changes in nest phenology are not necessarily uniform across the entire Arctic. Our results suggest some arctic-breeding shorebird and passerine species are altering their breeding phenology to initiate nesting earlier enabling them to, at least temporarily, avoid the negative consequences of a trophic mismatch.
Alaska↗
Characterizing range-wide population divergence in an alpine-endemic bird: A comparison of genetic and genomic approaches
The delineation of intraspecific units that are evolutionarily and demographically distinct is an important step in the development of species-specific management plans. Neutral genetic variation has served as the primary data source for delineating “evolutionarily significant units,” but with recent advances in genomic technology, we now have an unprecedented ability to utilize information about neutral and adaptive variation across the entire genome. Here, we use traditional genetic markers (microsatellites) and a newer reduced-representation genomic approach (single nucleotide polymorphisms) to delineate distinct groups of white-tailed ptarmigan (Lagopus leucura), an alpine-obligate species that is distributed in naturally fragmented habitats from Alaska to New Mexico. Five subspecies of white-tailed ptarmigan are currently recognized but their distinctiveness has not been verified with molecular data. Based on analyses of 436 samples at 12 microsatellite loci and 95 samples at 14,866 single nucleotide polymorphism loci, we provide strong support for treating two subspecies as distinct intraspecific units—L. l. altipetens, found in Colorado and neighboring states; and L. l. saxatilis, found on British Columbia’s Vancouver Island—but our findings reveal more moderate patterns of divergence within the remainder of the species’ range. Results based on genetic and genomic datasets generally agreed with one another, indicating that in many cases microsatellite loci may be sufficient for describing major patterns of genetic structure across species’ ranges. This work will inform future conservation and management decisions for the white-tailed ptarmigan, a species that may be vulnerable to future changes in climate.
Conservation Genetics↗
Wintering grounds leave their mark: Where birds winter influences genomic structure in Arctic nesting common eiders
Information about the distribution of genomic variation within and between nesting locations of waterfowl can aid in defining populations and conservation plans and inform harvest management. Identification of locations where shifts in allelic diversity occur is particularly important for Arctic nesting species nesting, a region currently experiencing rapid change associated with climate and other factors. Here, we build upon previous investigations on spatial patterns of genetic variation in a largely migratory, circumpolar breeding sea duck, the common eider ( Somateria mollissima ) through inclusion of additional sample locations and genomic markers. We analyzed double-digest restriction site-associated DNA sequences from 309 common eiders to estimate genetic variation within, and differentiation among, 21 nesting locations across North America. Our results corroborate previous evidence of four genetic groups that coincide with colonies that share similar winter areas. We found deeper genomic differences between common eiders wintering in the west (Pacific Ocean) versus the east (Atlantic Ocean and Hudson Bay). We also identified subtle structure, not previously recognized, within Hudson Bay nesting common eiders. Our findings add to evidence linking wintering areas and genomic differentiation in waterfowl, offering further insights for management of this culturally important sea duck species.
Conservation Genetics↗
Transfer of crude oil from contaminated water to bird eggs
Paris of breeding mallard ducks were exposed to oiled water for 2 days during the first week of incubation. Hatching success of ducks exposed to 100 ml of Prudhoe Bay crude oil per square meter of water surface was significantly less than that of controls. Hatching success of ducks exposed to 5 ml of crude oil per square meter of water surface was less than that of controls but the difference was not significant. The presence of oil on the eggs of ducks exposed to oiled water was confirmed by chemical analysis. Thermocouple probes were used to monitor the egg and nest temperatures of some of the ducks in each of the three groups. Incubation temperatures of oiled females were not significantly different from those of the controls. The incubation behavior of females exposed to oiled water and the first-week survival of their ducklings was not affected by the oil.
Environmental Research↗
Hepatic microsomal N-oxidation and N-demethylation of N,N-dimethylaniline in red-winged blackbird compared with rat and other birds
Hepatic microsomes prepared from red-winged blackbirds and albino rats were incubated with N,N-dimethylaniline (DMA)_in complete incubation mixtures at pH 7.9 and 37?C for 10 min. Formaldehyde and N,N-dimethylaniline--oxide produced from DMA were measured. Redwings were found to have significantly lower N-demethylation activities than rats, and redwings had only marginal or no N-oxidation activities. Hepatic microsomes from redwings did not further metabolize the N-oxide. The N-oxidation and N-demethylation activities of brown-headed cowbirds, common grackles, and starlings were similar to those of redwings.
Life Sciences↗
Comparative acute oral toxicity of pesticides to six species of birds
Acute oral LD50 values were determined for 16 common pesticides on mallard ducks ( Anas platyrhynchos ), ring-necked pheasants ( Phasianus colchicus ), chukar partridges ( Alectoris graeca ), coturnix quail ( Coturnix coturnix japonica ), common pigeons ( Columba livia ), and house sparrows ( Passer domesticus ). Analyses of the data revealed that (1) the average sensitivity of any one species to the 16 pesticides did not differ statistically from that of any other species, and (2) at the same time, the species varied widely in their sensitivity to any given compound. The average range of the LD50 values for single chemicals in the 6 species was nearly 10-fold. With differences of this magnitude, it is recommended that extrapolation of toxicity data from one species to another be avoided.
Toxicology and Applied Pharmacology↗
Responsiveness of 6 to 14 generations of birds to dietary dieldrin toxicity
The lethal dietary toxicity of dieldrin was estimated repeatedly during 8 years of testing young bobwhites (Colinus virginianus), Japanese quail (Coturnix c. japonica), ring-necked pheasants (Phasianus colchicus), and mallards (Anas platyrhynchos). Toxicities, quantified as 8-day LC50 values (5 days on toxic diet, followed by 3 days of untreated feed), were estimated at least 18 times per species. Average dietary LC50 values (ppm) and their 95% confidence limits for 14-day-old quail and 10-day-old pheasants and mallards were: bobwhite, 38 (34?42); Japanese quail, 61 (58?64); ring-necked pheasant, 56 (53?59); and mallard, 179 (163?195). No time-related changes were detected in LC50 values for any of the species.
Toxicology and Applied Pharmacology↗
Divergent effects of postmortem ambient temperature on organophosphorus- and carbamate-inhibited brain cholinesterase activity in birds
Time- and temperature-dependent postmortem changes in inhibited brain cholinesterase (ChE) activity may confound diagnosis of field poisoning of wildlife by anticholinesterase pesticide. Carbamate-inhibited ChE activity may return to normal within 1 to 2 days of exposure of intact carcass to moderate ambient temperature (18-32C). Organophosphorus-inhibited ChE activity becomes more depressed over the same time. Uninhibited ChE activity was resilient to above freezing temperature to 32C for 1 day and 25C for 3 days. Carbamate- and organophosphorus-inhibited ChE can be separated by incubation of homogenate for 1 hour at physiological temperatures; carbamylated ChE can be readily reactivated while phosphorylated ChE cannot.
Pesticide Biochemistry and Physiology↗
Response of palila and other subalpine Hawaiian forest bird species to prolonged drought and habitat degradation by feral ungulates
Extinction has claimed half of all historically-known Hawaiian passerines, and today many extant species are increasingly threatened due to the combined effects of invasive species and climate change. Habitat disturbance has affected populations of feeding specialists most profoundly, and our results indicate that specialists continue to be most vulnerable, although even some abundant, introduced, generalist species also may be affected. Surveys of passerines during 1998–2011 in subalpine woodland habitat on Mauna Kea Volcano, Island of Hawai′i, revealed that the abundance of the critically endangered palila ( Loxioides bailleui ), a seed specialist, declined by 79% after 2003. The ′akiapōlā′au ( Hemignathus munroi ), an endangered specialist insectivore, was not detected in the survey area after 1998. The Hawai′i ′amakihi ( Hemignathus virens virens ), a generalist feeder and the most abundant species on Mauna Kea, was the only native species to maintain a stable population. The Japanese white-eye ( Zosterops japonicus ), a well-entrenched generalist and one of the three most common introduced species, declined. Drought prevailed in 74% of months during 2000–2011, and dry conditions contributed to the recent decline of the palila by reducing the annual māmane ( Sophora chrysophylla ) seed pod crop, which influences palila breeding and survival. Sustained browsing by introduced ungulates also lowered habitat carrying capacity, and their elimination should reduce the effects of drought and promote forest restoration. Our results illustrate how the feeding ecology of a species can influence its response to interacting environmental perturbations, and they underscore the value of long-term monitoring to detect population trends of sensitive species.
Hawai'i↗
Pathways to strategic communication for biodiversity conservation: Response to “Hearing ourselves (and acting in consequence): A commentary on Bekessy et al. from a bird-handling environmental education perspective”
Central to discussions about the merits of ecosystem services as a communication strategy is the degree to which it represents a strategic and effective approach to advance biodiversity conservation. There is increasing recognition that many conservation communication efforts can be more strategic (e.g. Kusmanoff et al. 2016).
Biological Conservation↗
Facilitated adaptation for conservation – Can gene editing save Hawaii's endangered birds from climate driven avian malaria?
Avian malaria has played a significant role in causing extinctions, population declines, and limiting the elevational distribution of Hawaiian honeycreepers. Most threatened and endangered honeycreepers only exist in high-elevation forests where the risk of malaria infection is limited. Because Culex mosquito vectors and avian malaria dynamics are strongly influenced by temperature and rainfall, future climate change is predicted to expand malaria infection to high-elevation forests and intensify malaria infection at lower elevations, likely resulting in future extinctions and loss of avian biodiversity in Hawaii. Novel, landscape-level mosquito control strategies are promising, but are logistically challenging and require costly long-term efforts. As an alternative or supplemental strategy, we evaluated the potential of releasing a gene-edited malaria-resistant honeycreeper (Iiwi, Drepanis coccinea) in Hawaiian rainforests; a strategy known as facilitated adaptation. While this approach also has significant technical challenges and costs, it may offer a more permanent solution to increasing malaria threats. If malaria-resistant honeycreepers can be developed, facilitated adaptation may provide a practical strategy for the reestablishment of abundant avian populations in Hawaiian forests. A successful strategy could be the release of malaria-resistant Iiwi in mid-elevation forests where development of a resistant population has the best chance of success. Establishment of a resistant Iiwi population could provide a source for dispersal and development of resistant populations in high-elevation forests and a permanent source of resistant individuals for translocation to other vulnerable areas.
Hawaii↗
Incubation stage and polychlorinated biphenyl (PCB) congener patterns in an altricial and precocial bird species
The composition of polychlorinated biphenyl (PCB) congeners was compared between non-incubated and embryonated eggs of tree swallows ( Tachycineta bicolor ) and little terns ( Sterna albifrons ) to determine if measurable changes in PCB congeners occurred during the embryonic period. There was no indication of changes in PCB congener patterns over the incubation period in tree swallows in 1999 and 2000 at a site with very high PCB exposure or a site with more modest PCB exposure. Additionally, congeners known to be either quickly metabolized or conserved based on experimental studies did not generally respond as predicted. Similarly, PCB congener patterns in eggs of little terns from Bottsand, Schleswig-Holstein, Germany, did not differ between non-incubated and embryonated eggs. The results from both species suggest that the stage of incubation is not an important consideration when evaluating PCB congener patterns; comparisons and assessments can be made with eggs collected at all stages of incubation.
Environmental Pollution↗
Disentangling the effects of habitat biogeochemistry, food web structure, and diet composition on mercury bioaccumulation in a wetland bird
Methylmercury (MeHg) is a globally pervasive contaminant with known toxicity to humans and wildlife. Several sources of variation can lead to spatial differences in MeHg bioaccumulation within a species including: biogeochemical processes that influence MeHg production and availability within an organism’s home range; trophic positions of consumers and MeHg biomagnification efficiency in food webs; and individual prey preferences that influence diet composition. To better understand spatial variation in MeHg bioaccumulation within a species, we evaluated the effects of habitat biogeochemistry, food web structure, and diet composition in the wetland-obligate California black rail ( Laterallus jamaicensis coturniculus ) at three wetlands along the Petaluma River in northern San Francisco Bay, California, USA. The concentration of MeHg in sediments differed significantly among wetlands. We identified three sediment and porewater measurements that contributed significantly to a discriminant function explaining differences in habitat biogeochemistry among wetlands: the porewater concentration of ferrous iron, the percent organic matter, and the sediment MeHg concentration. Food web structure and biomagnification efficiency were similar among wetlands, with trophic magnification factors for MeHg ranging from 1.84 to 2.59. In addition, regurgitation samples indicated that black rails were dietary generalists with similar diets among wetlands (percent similarity indices > 70%). Given the similarities in diet composition, food web structure, and MeHg biomagnification efficiency among wetlands, we concluded that variation in habitat biogeochemistry and associated sediment MeHg production was the primary driver of differences in MeHg concentrations among black rails from different wetlands.
California↗