An evaluation of the Christmas Bird Count for monitoring population trends of selected species
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No abstract available.
The first North American breeding bird atlases were initiated during the 1970s. With atlases completed or ongoing in more than 40 U.S. states and most Canadian provinces, these projects are now familiar to professional ornithologists and amateur birders. This book provides the results of the Oklahoma Breeding Bird Atlas, the data for which were collected during 1997–2001. Its appearance less than 3 years after completing fieldwork is remarkable and everyone associated with its timely publication should be congratulated for their efforts. Review info: Oklahoma Breeding Bird Atlas. By Dan L. Reinking, 2004. ISBN: 0806136146, 528 pp.
Unretrieved loss for mourning doves (Zenaida macroura) in north-central South Carolina was between 27 and 41 percent of the retrieved kill for the 1973 through 1975 hunting seasons based on 1,396 doves shot by 281 hunters. Dove hunters hunted in groups, fired 8.6 shots per retrieved dove, and engaged in a substantial number of illegal activities. Increased dove populations and hunter bag resulted in increased unretrieved loss, numbers of shots per bagged bird, and illegal activities. Retriever dogs increased the efficiency of dove hunters.
A total of 36 roost sites of the Snail Kite (Rostrhamus sociabilis) were studied in southern Florida, of which four (11%) were used regularly for 6 or more years. Major roosts were also used as nesting sites. All roosts were in flooded marshes and 33 (91.6%) were in stands of coastal-plain willow. Population increase and the number of roosts were strongly correlated. The number of kites arriving at roosts before sunset was smaller than arriving after sunset (37.8:62.2%), and gray birds (adult and subadult males) generally went to roost earlier than brown birds (all females and immature males). Rites tended to go to roost earlier on cloudy days. Morning departure from roosts was over a much shorter time than arrivals in the afternoon. Ninety-two percent of the kite roosts were also used by other species of birds for roosting, 8 1% of which were eight species of herons.
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We developed a model to estimate the number of bird carcasses that were likely deposited on the beaches of St. Paul Island, Alaska following the M/V Citrus oil spill in February 1996. Most of the islands beaches were searched on an irregular schedule, resulting in the recovery of 876 King Eider carcasses. A sub-sample of beaches were intensively studied to estimate daily persistence rate and detection probability [Fowler, A.C., Flint, P.L., 1997. Marine Pollution Bulletin]. Using these data, our model predicted that an additional 733±70 King Eider carcasses were not detected during our searches. Therefore, we estimate that at least 1609±70 King Eider carcasses occurred on beaches as a result of the spill. We lacked sufficient sample size to model losses for other species, thus we applied the estimated recovery rate for King Eiders (54%) to other species and estimate a total combined loss of 1765 birds. In addition, 165 birds were captured alive making the total estimated number of birds impacted by the M/V Citrus spill 1930. Given that oiled birds occurred in places on the island which could not be systematically searched combined with the fact that it was unlikely that oiled birds that died at sea would have been recovered during our searches [Flint, P.L., Fowler, A.C., 1998. Marine Pollution Bulletin], our estimate of total mortality associated with the spill should be considered a minimum.
Abstract has not been submitted
[No abstract available]
Concentrations of mercury in passerine birds fed diets containing 40 ppm methylmercury were similar in tissues of birds that died from mercury poisoning and in those that were sacrificed after half the group had died. Residues were higher in tissues of birds that died, but the differences were not statistically significant. Residue levels were highest in livers, followed by kidneys and brains. Levels of mercury were similar in breast muscle, carcass, and whole body. Mercury levels were highest in redwinged blackbirds, lowest in grackles, and intermediate in starlings and cowbirds. Mercury concentrations exceeded 20 ppm in all tissues of all species and were similar to levels reported in wild birds known to have died of mercury poisoning.
Increased urban lighting on Kauai Island, Hawaii, has resulted in new problems for threatened and endangered procellariiform birds. Between 1978 and 1985,11,767 Kewell's shearwaters, 38 dark-rumped petrels, and 8 band-rumped storm petrels were attracted to bright urban lights, struck unseen objects, and fell to the ground. A salvage effort involving public cooperation and government-run 'aid stations' has returned 90% of these birds to the wild. Nightly fallout of seabirds was significantly reduced during the full moon, but fallout increased as the new moon approached. The heaviest fallout occurred in urban coastal areas, particularly at river mouths. More than 97% of the fallout involved fledgling birds apparently leaving their mountain nesting grounds for the first time. Less than 1%of these birds were recovered again on subsequent nights.
The effects of p,p?-DDE on the intensity of male Ringed Turtle Doves? courtship behavior were determined for dietary levels of 10 ppm and 50 ppm (dry weight). Pairs of doves were placed in cages for 12.5 min on 5 consecutive days for behavioral observation before dietary treatment and for periods 31-35 and 5963 days after initiation of the treated diet. Total amount of time spent displaying courtship behavior and bow-coo frequency were analyzed through video tape recording..... The 50.ppm diet caused a reduction in total courtship activity time and in bow-coo frequency for both posttreatment observation periods. The 10-ppm diet did not affect bow-coo frequency and total activity time at 31-35 days but did cause a significant reduction in courtship behavior during the 59-63.day observation period. The DDE residues found in the male Ringed Turtle Doves showing reduced courtship behavior were lower than residues found in many species of birds that have shown reproductive failures in the wild.
We conducted 164 diurnal morning point counts in 1997 and 89 nocturnal point counts in 1998 along the Rio Grande and at other riparian habitats on remote ranchland in northwestern Webb County. We subsequently conducted 94 diurnal morning and 37 nocturnal point counts in 1999 on public lands along the Rio Grande and at other riparian habitats at Laredo, Webb County. From these systematic surveys (n 384) and other irregular visits to sites during the length of the study, we detected a total of 209 bird species. Many species (97) are distributed widely over much of North America, but substantial numbers of species were also of primarily eastern (30), western (30), southwestern (26), and tropical (26) distributions. Fifty-five of the 209 species (26%) occur on >1 species priority lists in six bird conservation plans that we reviewed, but only four of these were tropical species. This suggests that tropical species, the driving force behind ecotourism-sustained economies in southern Texas, may not benefit directly from recent bird conservation plans, since their lists of priority species do not include many tropical birds. Thus, conservation projects designed to benefit primarily tropical species will not be ranked highly for funding if evaluated on the basis of the bird conservation plans we reviewed.
Certain aspects of woodcock usage of summer fields were studied in Maine. Findings were as follows: ....1. On two study fields in 1968, numbers of woodcock first began spending nights in the fields during the second week of June. During 1968 and 1969, the number of birds flushed from the fields varied greatly between nights. Use of fields continued into the first week of November......2. Woodcock started flying into summer fields approximately 26 minutes after sunset. Unless disturbed, birds remained on fields throughout the night and started departing for diurnal covers about 48 minutes before sunrise. The duration of evening and morning flight periods averaged 13 to 15 minutes.....3. Woodcock did not necessarily use the same field throughout the summer. Five of the 36 birds taken as repeats were caught on fields other than where originally banded. However, it was believed that flights to and from fields were essentially local movements.....4. Vegetation appeared to have been a critical factor influencing the distribution of woodcock in fields. Areas of low ground cover interspersed with taller and denser cover were used most frequently.....5. Immatures, especially immature males, were the predominant age-sex class captured on Maine summer fields. The question of whether the age-sex composition of birds using summer fields is atypical of the total woodcock population requires additional study.
No abstract available.
Wild and captive giant Canada geese (Branta canadensis maxima) and captive mallards (Anas platyrhynchos) accumulated ice on neck collars and/or nasal saddles during winter storm periods in 1971 and 1972. Weather conditions associated with icing were documented, and characteristics of icing are discussed. Severe marker icing occurred during subfreezing weather when the windchill reached approximately -37 deg.C. Birds appeared able to de-ice nasal saddles in most instances.
Thirty-two immature common yellowthroats were used to evaluate three methods of attaching radio transmitters to the backs of small passerines: adhesive, velcro, and harness. There were no significant differences between the three methods; however, the adhesive method of transmitter attachment to small birds was found to be the preferred technique.
The postnuptial and postjuvenal molts of Red-breasted Nuthatches occur from middle June to late September. Some birds may be nearly finished with the complete molt before other individuals begin, so that specimens taken at any given time may differ by as much as two months in the age of their plumage. No characters useful in ageing birds after the completion of the autumn molt were found.....The proposed racial subdivision of Sitta canadensis was based on misleading evidence resulting from variation of plumage age in birds assumed to be seasonally comparable, sooting of birds in industrialized parts of the country, and variation in quality of prepared specimens.