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161.
The breeding success and chronology of Wood Storks Mycteria americana were studied at eight colonies in northern and central Florida during 1981–1985. Mean ± s.d. clutch size for all colony-years was 3.07 ± 0.56 (n = 2694 nests), with three-egg clutches (72%) most frequent. Mean clutch size among all colonies and years ranged from 2.73 ± 0.55 to 3.41 ± 0.61. Many colonies exhibited significant negative trends in clutch size with, hatching date because of a proportional decrease in four-egg clutches later in the season. Mean colony clutch size was not correlated with nest numbers, nesting density or mean hatching date within most years. Mean ± s.d. number of fledglings for all colonies and years was 1.29 ± 1.16 fledglings per nest (n = 2812 nests). Mean annual fledging rates in colonies ranged from 0 (colony failed) to 2.66 fledglings per nest. Most breeding failure occurred prior to egg hatching, and the second highest mortality occurred between hatching and 2 weeks of age. Four-egg clutches fledged more storks than three-egg clutches, which in turn were more successful than two-egg clutches. However, all clutch sizes showed similar fledgling per egg rates. The seasonal decline in productivity was associated proportionally with smaller clutch sizes later in the breeding season. An increase in mean hatching date was correlated with an increase in latitude. There was greater within-year breeding synchrony among colonies than interyear breeding synchrony within each colony. Breeding synchrony was not correlated with mean hatching date, latitude, longitude, nest numbers or nesting density. 相似文献
162.
163.
Lori A. Randall Robert H. Diehl Barry C. Wilson Wylie C. Barrow JR. Clinton W. Jeske 《The Journal of wildlife management》2011,75(6):1324-1329
To protect and restore wintering waterfowl habitat, managers require knowledge of routine wintering waterfowl movements and habitat use. During preliminary screening of Doppler weather radar data we observed biological movements consistent with routine foraging flights of wintering waterfowl known to occur near Lacassine National Wildlife Refuge (NWR), Louisiana. During the winters of 2004–2005 and 2005–2006, we conducted field surveys to identify the source of the radar echoes emanating from Lacassine NWR. We compared field data to weather radar reflectivity data. Spatial and temporal patterns consistent with foraging flight movements appeared in weather radar data on all dates of field surveys. Dabbling ducks were the dominant taxa flying within the radar beam during the foraging flight period. Using linear regression, we found a positive log-linear relationship between average radar reflectivity (Z) and number of birds detected over the study area (P < 0.001, r2 = 0.62, n = 40). Ground observations and the statistically significant relationship between radar data and field data confirm that Doppler weather radar recorded the foraging flights of dabbling ducks. Weather radars may be effective tools for wintering waterfowl management because they provide broad-scale views of both diurnal and nocturnal movements. In addition, an extensive data archive enables the study of wintering waterfowl response to habitat loss, agricultural practices, wetland restoration, and other research questions that require multiple years of data. © 2011 The Wildlife Society. 相似文献
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165.
Abstract: Here we report an eggshell in Dominican amber, representing the first vertebrate egg in any amber deposit. The eggshell is compared with present-day eggs of lizards, snails and birds. Based on the surface structure and type of shell breakage, it appears that the most likely candidate is a bird, and with that consideration, an avian group that produces eggs similar to the fossil in shape, size and colouration is the Trochilidae (hummingbirds). Several possible explanations of how the fossil could be preserved in amber are provided. If indeed a hummingbird was involved, this discovery would represent the first New World record of a fossil trochilid. 相似文献
166.
Abstract: Researchers have extensively used mark—recapture techniques to obtain information on demographic parameters of wildlife populations. However, researchers have recognized that a number of factors can influence capture probabilities of wildlife species, which in turn can bias mark—recapture estimates of demographic parameters. Tooth extraction, which is a commonly used technique in studies of mesopredator species to obtain precise age estimates and to monitor the use of vaccine baits, is an aspect of animal handling that clearly might affect the recapture probability of individuals. However, the effect that tooth removal has on the individual recapture probabilities of wildlife species is unknown. During 2005, we trapped and marked 91 raccoons (Procyon lotor) in northern Indiana, USA, as part of a mark—recapture study designed specifically to determine if tooth extractions have an effect on recapture probabilities of individuals. We performed tooth extractions on 50% of the raccoons at the time of capture, and we attempted to balance tooth extractions with respect to sex and age of raccoons. We used logistic regression to model the effects of sex, age, and tooth removal on recapture probabilities, and we used Mann—Whitney U-tests to examine the effect of tooth removal on the number of times we recaptured individuals. The probability of recapture differed between sexes but did not differ as a function of tooth removal or among age classes. In addition, we failed to detect any difference in the mean number of times that we recaptured raccoons between the tooth removed and non—tooth-removed groups. Our results suggest that managers can use tooth extractions as an effective management tool without biasing population estimates or compromising other management objectives. 相似文献
167.
18S rRNA data indicate that Aschelminthes are polyphyletic in origin and consist of at least three distinct clades 总被引:7,自引:1,他引:6
Winnepenninckx B; Backeljau T; Mackey LY; Brooks JM; De Wachter R; Kumar S; Garey JR 《Molecular biology and evolution》1995,12(6):1132-1137
The Aschelminthes is a collection of at least eight animal phyla,
historically grouped together because the absence of a true body cavity was
perceived as a pseudocoelom. Analyses of 18S rRNA sequences from six
Aschelminth phyla (including four previously unpublished sequences) support
polyphyly for the Aschelminthes. At least three distinct groups of
Aschelminthes were detected: the Priapulida among the protostomes, the
Rotifera-Acanthocephala as a sister group to the protostomes, and the
Nematoda as a basal group to the triploblastic Eumetazoa.
相似文献
168.
CAMPBELL WILLIAM J.; ALLEN L. H. JR; BOWES GEORGE 《Journal of experimental botany》1990,41(4):427-433
Photosynthetic rates of outdoor-grown soybean (Glycine max L.Merr. cv. Bragg) canopies increased with increasing CO2 concentrationduring growth, before and after canopy closure (complete lightinterception), when measured over a wide range of solar irradiancevalues. Total canopy leaf area was greater as the CO2 concentrationduring growth was increased from 160 to 990 mm3 dm3.Photosynthetic rates of canopies grown at 330 and 660 mm3 CO2dm3 were similar when measured at the same CO2 concentrationsand high irradiance. There was no difference in ribulose bisphosphatecarboxylase/oxygenase (rubisco) activity or ribulose 1,5-bisphosphate(RuBP) concentration between plants grown at the two CO2 concentrations.However, photosynthetic rates averaged 87% greater for the canopiesgrown and measured at 660 mm3 CO2 dm3. A 10°C differencein air temperature during growth resulted in only a 4°Cleaf temperature difference, which was insufficient to changethe photosynthetic rate or rubisco activity in canopies grownand measured at either 330 or 660 mm3 CO2 dm3. RuBP concentrationsdecreased as air temperature during growth was increased atboth CO2 concentrations. These data indicate that the increasedphotosynthetic rates of soybean canopies at elevated CO2 aredue to several factors, including: more rapid development ofthe leaf area index; a reduction in substrate CO2 limitation;and no downward acclimation in photosynthetic capacity, as occurin some other species. Key words: CO2 concentration, soybean, canopy photosynthesis 相似文献
169.
170.
A Fossil Myxomycete Plasmodium from Eocene-Oligocene Amber of the Dominican Republic 总被引:1,自引:0,他引:1
BENJAMIN M. WAGGONER GEORGE O. POINAR JR. 《The Journal of eukaryotic microbiology》1992,39(5):639-642
ABSTRACT The first known fossil slime mold with part of the plasmodium preserved, from Eocene-Oligocene amber of the northern Dominican Republic, is described here. We assign it to the myxomycetes on the basis of its cytoplasmic structure. The paleoecological and evolutionary importance of this fossil is briefly discussed. 相似文献