scholarly journals Hypoxia Probably Does not Explain Short Incubation Periods of Woodpeckers

The Condor ◽  
2007 ◽  
Vol 109 (4) ◽  
pp. 976-979
Author(s):  
Karen L. Wiebe
Keyword(s):  
Sexual Selection ◽  
Partial Pressure ◽  
Ambient Air ◽  
Selective Force ◽  
Tree Cavities ◽  
Incubation Periods ◽  
Northern Flicker ◽  
Alternative Hypotheses ◽  
Colaptes Auratus ◽  
Ambient Levels

Abstract I tested the hypothesis that hypoxia in tree cavities causes the unusually short incubation periods characteristic of woodpeckers. I compared saturated O2 levels in ambient air to O2 levels in 13 unoccupied and 14 occupied nest cavities of the Northern Flicker (Colaptes auratus). Oxygen in unoccupied cavities did not differ from ambient levels, whereas O2 in cavities with an incubating adult was 2.2% lower than in saturated air. However, the magnitude of the decrease (20.5% oxygen in occupied cavities compared to 21.0% O2 in saturated air) is small compared to variation in the partial pressure of O2 caused by altitude. This suggests that O2 depletion is not a major selective force on embryonic development times for birds nesting in tree cavities. Alternative hypotheses for short incubation periods of woodpeckers include sexual selection on females and sibling competition.

Nest cavity availability and selection in aspen–conifer groves in a grassland landscape

2004 ◽  
Vol 34 (10) ◽  
pp. 2099-2109 ◽  
Author(s):  
Kathryn EH Aitken ◽  
Kathy Martin
Keyword(s):  
Resource Selection ◽  
Deciduous Forest ◽  
Tamiasciurus Hudsonicus ◽  
Habitat Features ◽  
Tree Cavities ◽  
Cavity Nesters ◽  
Dead Trees ◽  
Cavity Tree ◽  
Colaptes Auratus ◽  
Mountain Bluebirds

Cavity-nesting vertebrates, a significant component of forest wildlife communities, are connected ecologically in nest webs arranged in guilds of cavity producers (strong and weak excavators) and cavity consumers. The availability of tree cavities for nesting and roosting is considered critical to maintaining communities of cavity nesters. Using univariate tests and resource selection indices, we examined nesting use of both natural and excavated cavities in small aspen–conifer groves of interior British Columbia in relation to availability of cavity, tree, and habitat features. In a 2-year study, we monitored 197 cavities for use, 8% of which were lost between years. Of those that survived, 26% were occupied in both years, 29% were used in only one year, and 45% were not used in either year. Occupied cavities were larger internally than those not occupied in either year and were more likely to be in trees with only one cavity. In species-level resource selection analyses, tree swallows (Tachycineta bicolor Vieillot), European starlings (Sturnus vulgaris L.), and chickadees (Poecile spp.) used live, heart rot infected trees more than expected from their proportional abundance and used dead trees less than expected, while northern flickers (Colaptes auratus L.), mountain bluebirds (Sialia currucoides Bechstein), and red squirrels (Tamiasciurus hudsonicus Erxleben) used live and dead trees in proportion to their availability. Managed, open landscapes with small mixed or deciduous forest groves can sustain healthy communities of cavity nesters, if there is a range of suitable trees for excavators and open areas for foraging.

Maximal aerobic capacity at different levels of carboxyhemoglobin

1975 ◽  
Vol 38 (2) ◽  
pp. 300-303 ◽  
Author(s):  
S. M. Horvath ◽  
P. B. Raven ◽  
T. E. Dahms ◽  
D. J. Gray
Keyword(s):  
Critical Level ◽  
Aerobic Power ◽  
Ambient Air ◽  
Vo2 Max ◽  
Maximal Aerobic Capacity ◽  
Work Time ◽  
Maximum Aerobic Power ◽  
The Individual ◽  
Different Levels ◽  
Ambient Levels

Previous studies had indicated that maximum aerobic power (VO2 max) would be seriously impaired when HbCO levels were above 7% but was not altered if HbCO was around 2.7%. The present studies indicated that the critical level at which HbCO influenced VO2 max was approximately 4.3%. This was accompanied as in the above-noted studied with a reduction in total work time to the attainment of VO2 max. Two procedures to raise HbCO to appropriate levels were employed, i.e., a buildup wherin HbCO was incrementally increased by breathing ambient air containing 75 or 100 ppm CO and a bolus plus maintenance procedure. In the latter, HbCO was raised to the level attained in the buildup test by giving a “bolus” of CO followed by the continued inhalation of CO at a level to just maintain this level of HbCO regardless of the magnitude of the ventilation. Regardless of the mode of presentation, the decrement in VO2 max occurred at the same level of HbCO. These observations are of considerable significance, since it indicated that even low ambient levels of CO (23.7 ppm) would result in lowering maximum aerobic power if the individual had been previously exposed to CO such that the level was raised to this critical point.

scholarly journals Maximal exercise at extreme altitudes on Mount Everest

1983 ◽  
Vol 55 (3) ◽  
pp. 688-698 ◽  
Author(s):  
J. B. West ◽  
S. J. Boyer ◽  
D. J. Graber ◽  
P. H. Hackett ◽  
K. H. Maret ◽  
...  
Keyword(s):  
Partial Pressure ◽  
Maximal Exercise ◽  
Ambient Air ◽  
O2 Uptake ◽  
Mount Everest ◽  
Air Breathing ◽  
Co2 Partial Pressure ◽  
O2 Partial Pressure ◽  
Low Levels ◽  
Arterial Po2

Maximal exercise at extreme altitudes was studied during the course of the American Medical Research Expedition to Everest. Measurements were carried out at sea level [inspired O2 partial pressure (PO2) 147 Torr], 6,300 m during air breathing (inspired PO2 64 Torr), 6,300 m during 16% O2 breathing (inspired PO2 49 Torr), and 6,300 m during 14% O2 breathing (inspired PO2 43 Torr). The last PO2 is equivalent to that on the summit of Mt. Everest. All the 6,300 m studies were carried out in a warm well-equipped laboratory on well-acclimatized subjects. Maximal O2 uptake fell dramatically as the inspired PO2 was reduced to very low levels. However, two subjects were able to reach an O2 uptake of 1 l/min at the lowest inspired PO2. Arterial O2 saturations fell markedly and alveolar-arterial PO2 differences increased as the work rate was raised at high altitude, indicating diffusion limitation of O2 transfer. Maximal exercise ventilations exceeded 200 l/min at 6,300 m during air breathing but fell considerably at the lowest values of inspired PO2. Alveolar CO2 partial pressure was reduced to 7-8 Torr in one subject at the lowest inspired PO2, and the same value was obtained from alveolar gas samples taken by him at rest on the summit. The results help to explain how man can reach the highest point on earth while breathing ambient air.

Humidity-Dependent Cold Cells on the Antenna of the Stick Insect

2007 ◽  
Vol 97 (6) ◽  
pp. 3851-3858 ◽  
Author(s):  
Harald Tichy
Keyword(s):  
Water Vapor ◽  
Vapor Pressure ◽  
Partial Pressure ◽  
Systematic Study ◽  
Water Vapor Pressure ◽  
Ambient Air ◽  
Stick Insect ◽  
Proper Choice ◽  
Impulse Frequency ◽  
Order Of Magnitude

We present the first systematic study of the response of insect “cold cells” to a variation in the partial pressure of water vapor in ambient air. The cold cells on the antenna of the stick insect respond with an increase in activity when either the temperature or the partial pressure of water vapor is suddenly reduced. This double dependency does not in itself constitute bimodality because it could disappear with the proper choice of parameters involving temperature and humidity. In this study, we demonstrate that the evaporation of a small amount of water from the sensillum surface resulting from a drop in the water vapor pressure—leading to a transient drop in temperature and thus to a brief rise in impulse frequency—is the most plausible explanation for this bimodal response. We also show with an order-of-magnitude calculation that this mechanism is plausible and consistent with the amounts of water vapor potentially present on the sensillum. We hypothesize that a film of moisture collects on the hygroscopic sensillum surface at higher humidity and then tends to evaporate when humidity is lowered. The water might even be bound loosely within the cuticular wall, a situation conceivable in a sensillum that contains two hygroreceptive cells in addition to the cold cell.

New and little-known species of feather mites (Acari: Analgoidea: Pteronyssidae) from birds in North America

2006 ◽  
Vol 138 (2) ◽  
pp. 165-188 ◽  
Author(s):  
Sergei V. Mironov ◽  
Terry D. Galloway
Keyword(s):  
North America ◽  
Tree Swallow ◽  
Feather Mites ◽  
New Host ◽  
Cliff Swallow ◽  
Northern Flicker ◽  
Picoides Pubescens ◽  
Colaptes Auratus ◽  
First Time ◽  
New Host Records

AbstractIn this paper, we review the pteronyssid feather mites of the genera Pteronyssus Robin, Scutulanyssus Mironov, and Stenopteronyssus Faccini and Atyeo found in the course of an investigation into ectoparasites of birds in Canada. Five new species of feather mites are described: Pteronyssus sphyrapicinussp. nov. from the Yellow-bellied Sapsucker, Sphyrapicus varius (L.); Stenopteronyssus proctoraesp. nov. from the Northern Flicker, Colaptes auratus (L.); Scutulanyssus progneisp. nov. and Scutulanyssus subissp. nov. from the Purple Martin, Progne subis (L.); and Scutulanyssus petrochelidonissp. nov. from the Cliff Swallow, Petrochelidon pyrrhonota (Vieillot). New host records are provided for Pteronyssus picoides Černy and Schumilo from the Downy Woodpecker, Picoides pubescens (L.), and for Scutulanyssus obscurus (Berlese) from the Cliff Swallow; Pteronyssus brevipes Berlese and Scutulanyssus hirundicolus Mironov are formally recorded in North America for the first time; and Pteronyssus centurus McDaniel and Price is reported for the first time in Canada, from Lewis' Woodpecker, Melanerpes lewis (Gray). Scutulanyssus tyrrelli (Canestrini) is reported for the first time in Manitoba from the Tree Swallow, Tachycineta bicolor (Vieillot). Keys are provided for all species of Pteronyssus and Scutulanyssus found in North America.

Seasonal population dynamics of chewing lice (Phthiraptera: Amblycera and Ischnocera) infesting three species of woodpeckers (Aves: Piciformes: Picidae) in Manitoba, Canada

2016 ◽  
Vol 148 (6) ◽  
pp. 683-692 ◽  
Author(s):  
Robert J. Lamb ◽  
Terry D. Galloway
Keyword(s):  
Breeding Season ◽  
Seasonal Pattern ◽  
Seasonal Patterns ◽  
Chewing Lice ◽  
Northern Flicker ◽  
Picoides Pubescens ◽  
Colaptes Auratus ◽  
Male To Female ◽  
Seasonal Population ◽  
Seasonal Population Dynamics

AbstractThree species of woodpeckers (Piciformes: Picidae) in Manitoba, Canada, were examined for chewing lice (Phthiraptera): the resident downy woodpecker (Picoides pubescens(Linnaeus),n=55), and two migrants, yellow-bellied sapsucker (Sphyrapicus varius(Linnaeus),n=316) and northern flicker (Colaptes auratus(Linnaeus),n=225). Six species were collected:Menacanthus pici(Denny) (Amblycera: Menoponidae) from all hosts, and five species of Ischnocera (Philopteridae):Penenirmus auritus(Scopoli) from downy woodpeckers and sapsuckers,Picicola snodgrassi(Kellogg) andBrueelia straminea(Denny) from downy woodpeckers, andPenenirmus jungens(Kellogg) andPicicola porismaDalgleish from flickers. Adults and nymphs were present on downy woodpeckers all year, and on migrant sapsuckers and flickers from when they arrived until they left, suggesting lice reproduce continuously on their hosts. Prevalence and mean intensities of louse infestations generally decreased from their respective springtime levels to their lowest values during or at the end of the breeding season of their hosts, and then increased in various degrees during the fall. No seasonal pattern in louse sex ratios was observed except on northern flickers, where male to female ratios for two of three species were lowest during the breeding season. Resident and migrant hosts had similar seasonal patterns of infestation by lice.

scholarly journals Photosynthesis, Growth, and Yield Response of `Casselman' Plum to Various Ozone Partial Pressures during Orchard Establishment

1992 ◽  
Vol 117 (5) ◽  
pp. 703-710 ◽  
Author(s):  
W.A. Retzlaff ◽  
L.E. Williams ◽  
T.M. DeJong
Keyword(s):  
Partial Pressure ◽  
Ambient Air ◽  
Growth And Yield ◽  
Ozone Treatment ◽  
Atmospheric Ozone ◽  
Assimilation Rate ◽  
Cross Sectional ◽  
Ambient Ozone ◽  
Partial Pressures ◽  
Area Growth

Nursery stock of plum (Prunus salicina Lindel., `Casselman') was planted 1 Apr. 1988 in an experimental orchard at the Kearney Agricultural Center, Univ. of California, near Fresno. The trees were enclosed in open-top fumigation chambers on 1 May 1989 and exposed to three atmospheric ozone partial pressures (charcoal-filtered air, ambient air, and ambient air + ozone) from 8 May to 15 Nov. 1989 and from 9 Apr. to 9 Nov. 1990. Trees grown outside of chambers were used to assess chamber effects on tree performance. The mean 12-hour (0800-2000 hr Pacific Daylight Time) ozone partial pressures during the 2-year experimental period in the charcoal-filtered, ambient, ambient + ozone, and nonchamber treatments were 0.044, 0.059, 0.111, and 0.064 μPa·Pa-1 in 1989 and 0.038, 0.050, 0.090, and 0.050 pPa·Pa-1 in 1990, respectively. Leaf net CO2 assimilation rate of `Casselman' plum decreased with increasing atmospheric ozone partial pressure from the charcoal-filtered to ambient + ozone treatment. There was no difference in plum leaf net CO2 assimilation rate between the ambient chamber and nonchamber plots. Trees in the ambient + ozone treatment had greater leaf fall earlier in the growing season than those of the other treatments. Cross-sectional area growth of the trunk decreased with increasing atmospheric ozone partial pressures from the charcoal-filtered to ambient + ozone treatment. Yield of plum trees in 1990 was 8.8, 6.3, 5.5, and 5.5 kg/tree in the charcoal-filtered, ambient, ambient + ozone, and nonchamber treatments, respectively. Average fruit weight (grams/fruit) was not affected by atmospheric ozone partial pressure. Fruit count per tree decreased as atmospheric ozone partial pressure increased from the charcoal-filtered to ambient + ozone treatment. Decreases in leaf gas exchange and loss of leaf surface area were probable contributors to decreases in trunk cross-sectional area growth and yield of young `Casselman' plum trees during orchard establishment.

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