Progress 10/01/07 to 12/31/10
Outputs
OUTPUTS: This project is terminating early because the PI has retired. The original termination date was 09/30/2012. The most significant outputs and dissemination activities of the shortened project period (10/01/2007 to 13/31/2010) are: 1) graduate training leading to one Ph.D. (Jennifer Wang), and 2) four major publications reported in peer-reviewed scientific journals. PARTICIPANTS: Brenda J. Zaun U.S. Fish and Wildlife Service, Kauai National Wildlife Refuge Complex. TARGET AUDIENCES: Target audiences are various individuals, NGOs, and State and Federal agencies concerned with or charged with managing the endangered Hawaiian Goose, including the U.S. Fish and Wildlife Service and the Hawaiian Department of Land and Natural Resources. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Research conducted under this project resulted in new fundamental and applied knowledge significant enough to be included in the peer-reviewed publication listed below.
Publications
- Weathers, W.W. and B.J. Zaun. 2010. Egg-turning behavior and nest attentiveness of the endangered Hawaiian Goose on Kauai. Western Birds 41:2-9.
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Progress 01/01/09 to 12/31/09
Outputs
OUTPUTS: We conducted several censuses of waterbirds on Tomalas Bay using a light aircraft (Cessna 152) to count and photograph birds from an altitude of ca. 500 feet. Data from the censuses were made available to collaborators at Cypress Grove Research Center. We also collected incubation temperature data on cavity nesting birds. PARTICIPANTS: Brenda J. Zaun U.S. Fish and Wildlife Service, Kauai National Wildlife Refuge Complex. John P. Kelly. Cypress Grove Research Center P.O. Box 808 Marshall, CA 94940 Jennifer M. Wang. Department of Environmental Science, Policy and Management, University of California, Berkeley, CA 94720 Jennifer Wang was a graduate student and this research contributed to her Ph.D. dissertation. TARGET AUDIENCES: Target audiences are the U.S. Fish and Wildlife Service, California Department of Fish & Game, and Audubon Canyon Ranch, a conservation NGO. Information obtain through our research will aid staff of these organization with managing endangered species (the endangered Hawaiian Goose), the California Herring fishery, and Tomalas Bay's wild bird populations. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Research conducted during 2009 under this project resulted in new fundamental and applied knowledge significant enough to be included in peer-reviewed publications listed below.
Publications
- Zaun, B.J. and W.W. Weathers. 2009. Egg retrieval by the Hawaiian Goose after attempted predation by a cat. Western Birds 40:39-42.
- Wang, J.M. and W.W. Weathers. 2009. Egg laying, egg temperature, attentiveness, and incubation in the western bluebird. Wilson Journal of Ornithology 121(3):512-520.
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Progress 01/01/08 to 12/31/08
Outputs
OUTPUTS: In cooperation with Brenda J. Zaun (U.S. Fish and Wildlife Service, Kauai National Wildlife Refuge Complex), we monitored behavior of endangered Hawaiian Geese nesting at Kilauea Point National Wildlife Refuge, Kauai, Hawaii. We positioned infrared CCD video cameras near active goose nests and recorded nesting behavior from 26 December 2007 through 03 January 2008. We documented a first feral cat attack on an incubating goose and observed the first instance of egg retrieval by the Hawaiian goose. Video of the cat attack was posted on YouTube http://www.youtube.com/watchv=HraVzbpZ3o0 PARTICIPANTS: Brenda J. Zaun U.S. Fish and Wildlife Service, Kauai National Wildlife Refuge Complex. TARGET AUDIENCES: Target audience is U.S. Fish and Wildlife Service staff in charge of managinf the endangered Hawaiian Goose. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Research conducted during 2008 under this project resulted in new fundamental and applied knowledge significant enough to be included in a publication. In addition to the in press publication in the scientific peer-reviewed journal Western Birds on the endangered Hawaiian Nene, another manuscript on Nene is under review by Western Birds. Five previously unreported publications supported by this project are listed below for the first time.
Publications
- Stephens, C.M., R.B. Siegel, and W.W. Weathers. 2000. Thermal conductance and basal metabolism of the Orange-cheeked Waxbill (Estrilda melpoda). Ostrich 72:121-124.
- Kelly, J.P., N. Warnock, G.W. Page and W.W. Weathers. 2002. Effects of weather on daily body mass regulation in wintering dunlin. Journal Experimental Biology 205:109-120.
- Weathers, W.W., Davidson, C.L., Olson, C.R., Morton, M.L., Nur, N. and T.R. Famula. 2002. Altitudinal variation in parental energy expenditure by white-crowned sparrows. Journal of Experimental Biology 205:2915-2924.
- Kelly, J.P. and W.W. Weathers. 2002. Effects of feeding time constraints on body mass regulation and energy expenditure in wintering dunlin (Calidris alpina). Behavioral Ecology 13:766-775.
- Zaun, B.J. and W.W. Weathers. 2009. First record of egg retrieval by the Hawaiian goose. Western Birds 40: in press.
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Progress 01/01/07 to 12/31/07
Outputs
OUTPUTS: We used results from seven years of baywide winter waterbird surveys to calculate the total biomass of birds that feed on Pacific herring roe in Tomales Bay, California. We then used the biomass data to calculate each species' total energy requirement using equations that predict the energy expenditure of free-living wintering waterfowl and marine birds from body mass. Using Surf Scoters as an example, the calculations were as follows. The average winter abundance of Surf Scoters on Tomales Bay is 6810 individuals. Surf Scoters weigh 950 grams on average yielding a total Surf Scoter biomass on Tomales Bay of 6469.8 kg. The field metabolic rate predicted for a Surf Scoter of average mass is 1287 kJ/day. Multiplying this value by 6810 Surf Scoters gives a total daily energy expenditure of 8764 MJ/day. According to the USDA National Nutrient Data Laboratory (http://riley.nal.usda.gov/NDL/index.html) the energy content of herring roe is 3.08 MJ/kg wet weight. How much roe would
the Tomales Bay Surf Scoter population have to consume to supply this amount of energy? We calculated this value by multiplying the energy content of herring roe (3.08 MJ/kg) times the assimilation efficiency of roe (0.82), which we derived as follows. Of the metabolizable energy contained in Pacific herring eggs, 60% is derived from protein and 40% is derived from fat and carbohydrate. Only 70% of the energy contained in protein is available to birds, versus 100% of the energy contained in fat and carbohydrate. Based on these values, the overall assimilation efficiency of herring roe is 82%. Thus, birds eating herring roe obtain 2.53 MJ of usable energy per kilogram of eggs ingested. To obtain the 8764 MJ of energy required each day, Tomales Bay Surf Scoters would need to ingest 3,464 kg of roe (8,764 MJ/day divided by 2.53 MJ/kg). Repeating these calculations for all of the Tomales Bay waterbirds known to consume herring roe yielded a total consumption of 8,132 kg of roe per day.
Alternatively, instead of merely consuming roe to meet their routine energy requirement, birds might eat as much roe as possible, exploiting an abundant yet ephemeral food supply, to deposit body fat as a hedge against periods of reduced foraging efficiency. If so, maximal consumption rates could be 1.65 times those we calculated, or 13,417 kg/day. Our calculations show that Tomales Bay waterbirds could theoretically have consumed up to 88% of all the roe produced in 2005-06. If they did, the roe would provide 33.9 days of energy or 28% of their total seasonal energy needs. Repeating the calculations using the mean pre-1988 spawning biomass (6997 short tons) reveals that waterbirds could have obtained enough produces an amount of energy from roe sufficient to meet the waterbirds their needs for 118 days, nearly the entire 120 day season. This first order approximation suggests that herring roe is potentially of major importance to Tomales Bay waterbirds.
PARTICIPANTS: Dr. John P. Kelly. Partner organization Audubon Canyon Ranch. Professional development for Dr. Kelly.
TARGET AUDIENCES: California Depart of Fish & Game, various conservation oriented NGO such as Golden Gate Audubon Society, Audubon Canyon Ranch, and ecosystem-level wildlife ecologists.
PROJECT MODIFICATIONS: No changes were made.
Impacts
During winter, Tomales Bay, California plays host to over 57 species of waterbirds and provides spawning habitat for Pacific herring (Clupea harengus pallasi) that move into the bay between late November and early March to lay their eggs on the eelgrass. Spawning herring provide food for a variety of animals including invertebrates, fish, birds and mammals and since 1973 have made herring one of California's most valuable fisheries. We assessed how important herring eggs might be to Tomales Bay waterbirds by calculating the birds' energy requirements and estimating how much of those requirements could be met by consuming herring roe. Our calculations show that Tomales Bay waterbirds could theoretically have consumed up to 88% all of the roe produced in 2005-06. If they did, the roe would provide 33.9 days of energy or 28% of their total seasonal energy needs. Repeating the calculations using the mean pre-1988 spawning biomass (6997 short tons) reveals that waterbirds
could have obtained enough energy from roe to meet their needs for 118 days, nearly the entire 120 day winter season. This first order approximation suggests the potentially major importance of herring roe to Tomales Bay waterbirds. California's Department of Fish and Game monitors the state's herring population and typically sets the maximal annual fishery quota at between 15-20% of previous season's biomass, a level of harvest thought to be sustainable. Yet Tomales Bay spawning biomass has ranged widely from a high of 22,163 short tons in 1977-78 to a low of 345 short tons in 1990-91, making quota-setting inexact at best. Superimposed upon the year-to-year variability, there has been a long term population decline, with spawning biomass falling from 6697 tons per season before 1988 (14-year average) to 3,174 tons per season since then (18-year average), a significant decline of one-half (t30 = 2.57, P < 0.02). Our calculations suggest that dwindling Pacific herring stocks may be
adversely affecting marine birds that feed on herring or their roe.
Publications
- Weathers, W. W., and J. P. Kelly. 2007. Energy footprints on Tomales Bay: the importance of ephemeral food abundance to wintering waterbirds. The Ardeid 2007. Audubon Canyon Ranch, Stinson Beach CA. [available online: http://egret.org/pdfs/Ardeid2007.pdf].
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Progress 01/01/05 to 12/31/05
Outputs
The project's goals are to determine how egg temperature and female attentiveness of passerine birds varies with incubation stage (embryo age)and ambient temperature. The research tests a mathematical model that describes relative investment in parental self-maintenance versus embryo developmental rate, and the extent to which performance for either is compromised by integration of both functions. The project also examines whether exposure of newly-laid eggs to ambient temperatures above physiological zero induces embryonic development in the absence of incubation. If so, eggs that experience preincubation development should require less incubation time to hatch than non-exposed eggs subject to similar incubation patterns. Thus far we have monitored incubation temperature in 19 nests of four species (Oak Titmouse, Western Bluebird, Violet-green Swallow and Tree Swallow) and obtained over 100 total days of temperature observations. We also developed methods to
simultaneously record incubation behavior using miniature video cameras installed in the nest boxes in conjunction with field portable digital video cameras. We have amassed a huge amount of video and temperature data which is currently undergoing analysis.
Impacts
This study will interest avian biologists who are concerned with the thermal consequences of incubation behavior in birds. Mean egg temperature data determined in natural wild populations will also be of interest to aviculturalists who artificially incubate passerine bird's eggs.
Publications
- No publications reported this period
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Progress 01/01/04 to 12/31/04
Outputs
Antarctic fulmarine petrels breed in some of the coldest conditions encountered by any bird and their young grow twice as fast as predicted allometrically. To examine the energetic consequences of fast growth in a cold environment, we used the doubly labeled water technique to measure field metabolic rates of adults (three species) and different-aged nestlings (four species) of Antarctic fulmarine petrels in the Rauer Islands, East Antarctica: Antarctic fulmar Fulmarus glacialoides, Antarctic petrel Thalassoica antarctica, Cape petrel Daption capense, and snow petrel Pagodroma nivea. We used our data to assess parental effort and, together with literature values on nestling growth and resting metabolic rate, to construct and partition nestling energy budgets. Nestling total energy expenditure and peak daily metabolic rate were significantly higher than predicted allometrically (33-73% and 17-66% higher, respectively), and the relative cost of growth in nestling
petrels was among the highest reported for birds (54-72 kJ g-1). Parental effort during the nestling-feeding period was identical in adult Cape and Antarctic petrels (3.5 times BMR), and was somewhat (but not significantly) higher in snow petrels (4.6 times BMR). These values are comparable to those of other high-latitude procellariiform birds. Thus, despite the constraints of a compressed breeding season, cold temperatures, and fast-growing nestlings, adult Antarctic fulmarine petrels do not work harder than procellariid adults whose chicks grow much more slowly. Our findings suggest that obtaining sufficient food is generally not a constraint for adult fulmarine petrels and that factors operating at the tissue level limit nestling growth rate.
Impacts
This study will interest avian biologists who are concerned with the energetic consequences of different developmental modes exhibited by birds. The field energetics component of the study will potentially interest wildlife biologists and resource managers concerned with species management.
Publications
- Hodum, P.J. and W.W. Weathers. 2003. Energetics of nestling growth and parental effort in Antarctic fulmarine petrels. Journal Experimental Biology 206:2125-2133.
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Progress 01/01/03 to 12/31/03
Outputs
We determined the energy budget of nestling Mountain White-crowned Sparrows (Zonotrichia leucophrys oriantha) at a 2900-m high subalpine site by combining growth data with measurements of field metabolic rate (doubly labeled water technique) and resting metabolic rate made on different-aged nestlings. Nestling sparrows grow rapidly (their logistic growth rate constant is 129% of the allometric prediction) and they fledge at 9 days of age weighing 20.6 g (75% of adult mass). Relatively rapid growth in a cool montane environment (mean daytime air temperature = 16.5 +/- 1.4 degrees Celsius) is associated with high daily and total nestling energy requirements. During the 9 days between hatching and fledging, each nestling metabolized a total of 443 kJ of energy; a value 25% higher than expected for an open-nesting passerine bird. The relative cost of producing a fledgling White-crowned Sparrow (21.5 kJ per gram body mass) exceeds that of the three other open-nesting
passerine species that have been measured with doubly labeled water (range 16.5-19.3 kJ g-1). The energy that nestling sparrows accumulated as new tissue (115 kJ) constituted 26% of the total energy metabolized; substantially less than the 37% allocated to activity and thermoregulation combined. Nestling White-crowned Sparrows allocated more energy to activity and thermoregulation than nestlings of most other parent-fed species, but much less than the 50-53% of total metabolizable energy allocated by precocial shorebird chicks
Impacts
This study will interest avian biologists who are concerned with the energetic consequences of different developmental modes exhibited by birds. The field energetics component of the study will potentially interest wildlife biologists and resource managers concerned with species management.
Publications
- Weathers, W.W., Davidson, C.L., and M. L. Morton. 2003. Energetics of altricial nestlings in cold climates: insights from the mountain white-crowned sparrow. Condor 105:707-718.
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Progress 01/01/02 to 12/31/02
Outputs
We examined the physiological responses of captive bred Gouldian Finches (Erythrura gouldiae) to temperature by measuring their metabolic heat production (Hm, calculated from oxygen consumption), body temperature (Tb), and evaporative heat loss (He, calculated from evaporative water loss) at ambient temperatures (Ta) between 0 and 44 degrees C. Overall, we found the Gouldian Finch to resemble other small tropical seed-eaters that forage in open, sunlit situations. Its active phase basal metabolic rate (13.4 mW g-1; n = 11) was relatively low (61% of predicted allometrically) and it had only a modest capacity for evaporative cooling at high temperatures, dissipating evaporatively a maximum of 118% of its metabolic heat production above 40 degrees C. Like other small tropical birds, the Gouldian Finch develops substantial hyperthermia at high temperature, maintaining its Tb an average of 1.4 degrees C above Ta at Tas between 41.8-43.6 degrees C. At Tas above the upper
critical temperature (38 degrees C), metabolic heat production increases linearly with Ta according to the relation: Hm (mW g-1) = -12.4 + 0.68 Ta. The slope of this relation, termed the coefficient of heat strain (hs), provides an integrated measure of the metabolic response to heat. For 38 bird species, hs (mW g-1 oC-1) varies with body size according to the relation: log hs = log 7.83 - 0.54 log m, where m equals mass in grams. The Gouldian Finch's hs is only 40% of that predicted for a 17.1-g bird by this equation, proportionately the lowest value yet measured. Although aviculturalists widely regard the Gouldian Finch as cold intolerant, Ta in its northern Australian range sometimes falls to below freezing. Not surprisingly, we found the Gouldian Finch is actually better insulated than the average songbird its size; its thermal conductance (0.184 mL O2 g-1 h-1 oC-1) being 81% of predicted allometrically.
Impacts
These studies will help breeders establish optimal conditions for keeping Gouldian Finches (an important cage bird species) in captivity and aid wildlife biologists, policy makers and resource managers conserve this endangered species.
Publications
- Burton, C.T. and W.W. Weathers. 2002. Energetics and thermoregulation of the Gouldian Finch (Erythurua gouldiae). Emu 102:1-10.
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Progress 01/01/01 to 12/31/01
Outputs
We used open-circuit respirometry and the doubly labeled water technique (DLW) to examine the thermal ecology and ecological energetics of California Spotted Owls (Strix occidentalis occidentalis). Our physiological and behavioral observations indicated that Spotted Owls are less heat tolerant than typical birds. At temperatures above the thermoneutral zone (18-35 C), resting metabolic rate increased 1.48 times faster than predicted allometrically, and behavioral responses to heat stress (increased breathing rate, ptiloerection, gaping, and wing drooping) occurred at relatively modest temperatures, 30-34 C. Our data support the hypothesis that Spotted Owls prefer old-growth and late seral stage forests because they provide favorable microclimates. Our metabolic measurements reveal that Spotted Owls have exceptionally low energy requirements. Their basal metabolic rate, 10.13 ,b 0.46 J/(g hr), is only 82% of that predicted allometrically for owls. Field metabolic rate
(FMR) of five adults provisioning dependent young averaged 249 ,b 60 kJ/day, only 34% of that predicted for comparably sized non-passerine birds. We calculated Spotted Owl prey requirements from our FMR data, laboratory determinations of assimilation efficiency (77%), and the body composition of representative prey types. On average, Spotted Owls feeding young can meet their own energy needs by consuming one northern flying squirrel (Glaucomys sabrinus) every 1.8 days or one woodrat (Neotoma fuscipes) every 3.7 days.
Impacts
These studies have no immediate economic impact. They are of interest principally to wildlife biologists, policy makers and forest managers concerned with old-growth forests.
Publications
- Weathers, W.W., Hodum, P.J. and Blakesley, J.A. 2001. Thermal ecology and ecological energetics of California spotted owls. Condor 103:678-690.
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Progress 01/01/00 to 12/31/00
Outputs
We used the doubly labeled water (DLW) method to measure field metabolic rate (FMR) and water turnover during winter and summer in a very small (6.5 g) insectivorous desert passerine bird, the verdin (Auriparus flaviceps). Concurrently, we monitored weather conditions and used time-activity budget data of free-living birds and laboratory data on resting metabolism to construct time-activity laboratory (TAL) estimates of daily energy expenditure (DEE ) and to partition the verdins' energy budget into thermoregulatory, activity and basal components. The mean FMR of adult verdins was 33.6 kJ/day in winter (S.E.M.=0.9 kJ/day,N=14) and 22.8 kJ/day in summer (S.E.M.=0.45 kJ/day, N=7). FMR correlated negatively with the mean standard operative environmental temperature (Tes) prevailing during the measurement period. TAL analysis produced DEE estimates that corresponded on average to within -0.9% of our DLW-measured FMR values (range of individual values -18.3% to +14.3 %).
Metabolic expeditures for cold defense were 19.5% of DEE in winter (computed assuming substitution of exercise thermogenesis for hermoregulatory costs in active birds). In the summer, thermoregulatory costs amounted to 9.0% of DEE for keeping warm and 1.0% of DEE for keeping cool in the heat. Activity costs were 21.0% of DEE in winter and 17.5% of DEE in summer. Water efflux of nonbreeding adult verdins was 3.9 ml day-1 (624 ml per kg/day) in summer (N=5) and 3.4 ml/day (498 ml per kg/day) in winter (N=14). The water economy index (WEI; water efflux per unit FMR) of verdins was higher in summer (0.17 ml/kJ) than in winter (0.10 ml/kJ) and correlated negatively with mean Tes.
Impacts
These studies have no immediate economic impact. They are of interest principally to wildlife biologists and scientists pursuing curiosity-driven basic research.
Publications
- Webster, M.D. and W.W. Weathers. 2000. Seasonal changes in energy and water use by verdins, Auriparus flaviceps. Journal Experimental Biology 203: 3333-3344.
- Lynn, S.E., A.M. Houtmann, W.W. Weathers, E.D. Ketterson, and V. Nolan, Jr. 2000. Testerone increases activity but not daily energy expenditure in captive male dark-eyed juncos (Junco hyemalis). Animal Behaviour 60:581-587.
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Progress 01/01/99 to 12/31/99
Outputs
This project focuses on understanding the links between behavior, thermal environment and energy metabolism in non-domestic birds. It seeks to improve our understanding of the role of energy metabolism in shaping avian life histories and consequently its effect on the spacial distribution and abundance of birds. By studying the economics of energy acquisition and utilization we attain insights into the evolution of life history strategies, and ultimately, into the factors that determine species distribution and abundance. Studies published this year examined methods for assessing parental effort, the relation between male paternity and chick-feeding rules, the link between individual fitness and energy expenditure, and seasonal variation in energy demand of a non-migratory sparrow. One study tested the peak load reduction hypothesis, which suggests that hatching asynchrony in altricial birds is adaptive because it reduces parental workload during the most
energetically costly time in brood rearing. By staggering the ages of their offspring, parents may ensure that all nestlings do not reach maximum energy demand simultaneously. To test the hypothesis, we used the doubly labeled water technique to measure the energy expenditure of green-rumped parrotlets (Forpus passerinus) that reared experimentally manipulated synchronous and asynchronous broods. Peak metabolic rates of the two experimental groups did not differ, but parents of asynchronous broods metabolized significantly less energy than did parents of synchronous broods throughout the first half of the brood-rearing period. Our results indicate that hatching asynchrony in parrotlets substantially shortens the temporal duration of high brood energy demand, but does not reduce the magnitude of peak energy demand.
Impacts
Four of the five papers published this year provide tests of fundamental hypotheses concerning energy allocation. The fifth paper compares the reliability of commonly used behavioral measures of parental effort. These studies have no immediate economic impact. They are of interest principally to wildlife biologists and scientists pursuing curiosity-driven basic research.
Publications
- Weathers, W.W., C.R. Olson, R.B. Siegel, and T.R. Famula. 1999. Winter and breeding-season energetics of non-migratory White-crowned Sparrows. Auk 116:842-847.
- Sullivan, K.A., J.J. Roper, and W.W. Weathers. 1999. Individual variation in renesting intervals, daily energy expenditure, and reproductive success in passerines, pp. 401-411. In: Adams, N.J. and Slotow, R. H. (eds) Proc. 22 Int. Ornithol. Cong., Durban. Johannesburg: BirdLife South Africa.
- Siegel R.B., W.W. Weathers, and S.R. Beissinger. 1999. Assessing parental effort in a Neotropical parrot: a comparison of methods. Animal Behaviour 57:73-79.
- Siegel R.B., W.W. Weathers, and S.R. Beissinger. 1999. Hatching asynchrony reduces the duration, not the magnitude, of peak load in breeding green-rumped parrotlets. Behavioral Ecology and Sociobiology 45:444-450.
- Dickinson, J.L., and W.W. Weathers. 1999. Replacement males in the western bluebird: opportunity for paternity, chick-feeding rules, and fitness consequences of male paternal care. Behavioural Ecol. Sociobiol. 45:201-209
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Progress 01/01/98 to 12/31/98
Outputs
We used time-lapse photography to record mound-tending behaviour by mallee-fowl breeding in lower Murray River mallee. We also derived time budgets based on 149 h of behavioural observations of two focal individuals. We found striking behavioural differences between these mallee-fowl and those studied by Frith near Griffith, New South Wales: Murray River mallee-fowl: 1) did not differ in the proportion of days that mounds were tended in January and March; 2) were highly social, not solitary; and 3) shared mound-tending duties between sexes. On days when eggs were laid in January, both members of four pairs worked their mounds simultaneously 55+/-26 (SD) % of the time. In March after egg-laying had ceased, both members of two observed pairs worked simultaneously 68+/-30% and 86+/-9% of the time. In January and March, pairs spent an average of 6.8 +/- 2.5 and 7.2 +/- 0.6h opening and closing mounds, respectively, on days that mounds were attended. This equals 46 and
55%, respectively, of a single days activity. Male and female mallee-fowl moved similar amounts of sand per scratch when tending their mounds. We estimate that mallee-fowl move a total of about 3.3 tonnnes of sand to open and close the mound for egg-laying or to check its temperature. Our calculations suggest that it makes relatively little energetic difference to females whether or not they tend mounds, which may explain why females tended mounds at our study site.
Impacts
(N/A)
Publications
- Seymour, R.S., P.C. Withers and W.W. Weathers. 1998. Energetics of burrowing, running, and free-living in the Namib Desert golden mole (Eremitalpa namibensis). J. Zool., Lond. 244:107-117.
- Hainsworth, F.R., T. Moonan, M.A. Voos, K.A. Sullivan, and W.W. Weathers. 1998. Time and heat allocations to balance conflicting demands during intermittent incubation by yellow-eyed juncos. J.
- Hodum, P.J., W.J. Sydeman, G.H. Visser, and W.W. Weathers. 1998. Energy expenditure and food requirements of Cassin's Auklets provisioning nestlings. Condor 100:546-550.
- Weathers, W.W., and R.S. Seymour. 1998. Behaviour and time-activity budgets of mallee-fowl Leipoa ocellata in South Australia. Emu
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Progress 01/01/97 to 12/01/97
Outputs
Bridled Titmice (Baeolophus wollweberi) and Juniper Titmice (Baeolophus ridgwayi) occur sympatrically in southeastern Arizona, with Bridled Titmice preferring habitats that are more heavily vegetated, moister, and cooler than those occupied by Juniper Titmice. To assess whether these differences in habitat preference have physiological correlates, we measured the oxygen consumption, evaporative water loss, and body temperature of postbreeding titmice at ambient temperatures between 24-44 degrees C. Bridled Titmice were less tolerant of heat than Juniper Titmice and had significantly higher rates of metabolic heat production and evaporative water loss, but not body temperature, at ambient temperatures above 40 degrees C. These differences were entirely attributable to the Bridled Titmouse's smaller body size (10 vs. 15 g), and the differences vanished when rates were expressed per unit metabolic mass (mass raised to either the 2/3 or 2/4 power). Within the
thermoneutral zone, the rate of evaporative water loss (EWL) was significantly lower in Juniper Titmice than Bridled Titmice, even after accounting for the difference in body size. Reduced EWL is characteristic of species from hotter, drier habitats and suggests that physiology plays a role in these species' habitat preference.
Impacts
(N/A)
Publications
- WEATHERS, W.W. and GREENE, E. 1998. Thermoregulatory responses of Bridled and Juniper Titmice to high temperature. Condor 100: (in
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Progress 01/01/96 to 12/30/96
Outputs
Field metabolic rate (FMR) and water influx of New Holland Honeyeaters (Phylidonyris novaehollandiae, Eastern Spinebills (Acanthorhynchus tenuirostris) and a Crescent Honeyeater (P. pyrrhoptera) were measured using the doubly labeled water (DLW) technique. New Holland Honeyeaters had just finished breeding and were beginning their summer molt. Eastern Spinebills were still feeding young and had yet to begin molting and the Crescent Honeyeater was in late primary molt. FMRs of the three species averaged between 2.5-2.8 times their measured basal metabolic rate. Water influx rates (mainly nectar) ranged between 8.7 to 12.5 mL/day. The FMR of NHHEs varied inversely with mean environmental temperature. Honeyeater FMRs were much lower than would be predicted allometrically for hummingbirds of the same mass, reflecting the honeyeaters' low-cost foraging tactic of consuming nectar while perched.
Impacts
(N/A)
Publications
- WEATHERS, W. W., PATON, D. C. AND SEYMOUR, R. S. 1996. Field metabolic rate and water flux of nectarivorous honeyeaters. Aust. J. Zool. 44:445-460.
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Progress 01/01/95 to 12/30/95
Outputs
The avian postnatal metabolic-rate literature was reviewed using allometric equations, log Y = log a + b M, to describe the relation between postnatal resting metabolic rate (RMR) and chick body mass (M) for 25 species. In altricial species the relation between RMR and M from hatching to fledging can be described by a single equation whereas in most non-altricial species two such equations are needed; one for chicks weighing less than about 25% of mature mass (Ma) and a second for larger chicks. For altricial chicks and larger non-altricial chicks, the body-mass exponent, b, of 25 intraspecific allometric equations ranged from 0.25 to 1.67 and varied inversely with Ma. The scaling of postnatal RMR is thus unlike that of either adult or hatchling metabolismin that it is size-dependent. In altricial chicks and larger non-altricial chicks, the scaling coefficient, a, of the inter-specific power equations varied with adult mass according to the phylogenetically determined
relation log a(kJ/h) = log 0.0052 + 0.65 Ma, and was higher in fed than in fasted chicks. Equations derived in this analysis permit one to estimate the RMR of a growing chick from its mass and adult body mass, and provide a basis for evolutionary and ecological comparisons.
Impacts
(N/A)
Publications
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Progress 01/01/94 to 12/30/94
Outputs
Malleefowl artificially incubate their eggs in mounds containing decaying vegetation. The effort involved in behaviourally regulating mound temperature seems prodigious. We estimated its energy cost indirectly, using time to onset of an evaporative heat loss behaviour (gular flutter) to establish equivalent work rates for malleefowl running on a treadmill in the laboratory and for malleefowl tending mounds in the field. Equivalency between laboratory and field thermal environments was established based on operative temperature and water vapour pressure. Mound work was equivalent to running at 0.57 m/s. The power input of birds running this speed was 12.9 W/kg, which is 3.1 times the resting metabolic rate, or 3.8 times the basal metabolic rate. In March, malleefowl tend their mounds for an average of 4.8 to 5.3 h/day and incur a daily energy cost of incubation about twice that of other birds. At other times of the year malleefowl devote little effort to incubation.
Overall, the total work to construct a mound and tend it during the 5- to 6-month incubation period exceeds the total energy cost of incubation in typical birds by perhaps twofold. The benefits that compensate the malleefowl's higher total incubation cost include higher fecundity and emancipation from post-hatching parental care.
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Progress 01/01/93 to 12/30/93
Outputs
We evaluated two competing hypotheses concerning how field metabolic rate (FMR) of birds should vary seasonally. In both yellow-eyed juncos (Junco phaeonotus) and dark-eyed juncos (J. hymenalis), winter FMR, as measured by doubly labeled water, averaged 70.5 kJ/d which is not significantly different from each species' average breeding season value. We used behavioral, meteorological and laboratory metabolism data to calculate the energy devoted to thermoregulation under field conditions during the winter. Our analysis revealed that all of the heat produced as a by-product of physical activity contributed to thermoregulation. Thus, behavior has no net energy cost at low temperatures in juncos. Our data also suggest that winter is a period of greater energy stringency for juncos than the breeding season.
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Progress 01/01/92 to 12/30/92
Outputs
Two projects were initiated this year. One seeks to determine the thermal ecology, energy expenditure and food requirements of free-living spotted owls, Strix occidentalis; the other examines reproductive effort and seasonal energetics of sedentary vs. migratory populations of the native white-crowned sparrow, Zonotrichia leucophrys. This year we began field work with spotted owls in Lassen National forest and succeeded in measuring the field metabolic rate of one owl using the doubly labeled water technique. Laboratory measurements of owl resting metabolic rate at various stable ambient temperatures are in progress. Studies of sparrow field metabolic rates have begun, but data are not yet available.
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Progress 10/01/87 to 09/30/92
Outputs
An empirically based mathematical model was derived that accounts for 99 percentof the variation in total energy metabolized by birds from hatching to fledging, or to attaining adult size, given only two parameters; body mass at fledging and time to fledging. These two variates also account for 96 percent of the variation in peak energy demand by growing birds. We also tested the hypothesis that sex-biased provisioning by parent birds is accounted for by differences in the energy requirements of male and female chicks. It is not.
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Progress 01/01/90 to 12/30/90
Outputs
Adult yellow-eyed juncos feeding young adjust both the amount of time they spendforaging and their foraging efficiency to meet changing energy demands and time constraints. The foraging efficiency of independent young juncos increases linearly with age, but does not reach even the lowest adult level until four months of age. The young juncos' inefficient foraging is a major cause of their high mortality rate. Field measurements of 6-g verdins reveals proportional substitution of heat produced by foraging activity for the thermoregulatory requirement at low temperatures. Time-budget estimates of field metabolic rates should take this into account. Nestling acorn woodpeckers have the lowest growth efficiency of any bird yet measured. This is due to their remarkably slow growth (perhaps due to tannins in their partially acorn diet) and their high thermoregulatory requirement, which is a consequence of their slow feather development and cool nest environment. The
evolution of cooperative breeding in this species may have been in response to the nestlings's unusual energy requirements. The discovery of polygyny in the mallee fowl means that population estimates of this endangered species are probably too low.
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Progress 01/01/89 to 12/30/89
Outputs
We measured the allocation of time and energy in a population of adult yellow-eyed juncos (Junco phaeonotus) and their young (nestlings, fledglings, independent juveniles) throughout the breeding season using concurrent time-activity budgets and doubly labeled water (DLW). We constructed energy budgets by extrapolating laboratory measurements of metabolic heat production to field conditions using a linear heat transfer model and the operative temperature and wind speed experienced by the freeliving bird. From our data we calculated total daily energy expenditure (DEE), the proportion of DEE allocated to physical activity versus maintenance metabolism (basal + thermostatic costs), and foraging efficiency. We examined diet selectivity among parents and their young, and we calculated prey capture rates based on the measured energy content of insect prey. We also used the DLW method to measure the energy metabolism of free-living tropical hummingbirds and investigated
nest attentiveness in juncos.
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Progress 01/01/88 to 12/30/88
Outputs
We have experimentally validated a single-sample variant of the doubly labeled water method for measuring metabolic rate and water turnover in birds. CO(subscript 2) production based on doubly labeled water differed from Haldane values by <0.5% on average (range - 8.3 to 11.2%, n = 9). Water flux measured by the single-sample methods was comparable to the standard, two-sample technique. The influence of wind and air temperature on oxygen consumption, body temperature and thermal resistance of 6-g verdins (Auriparus flaviceps) was determined with a wind-tunnel respirometer. Operative temperature calculated using meteorological data was compared with direct measurements from taxidermic mounts of Brewer's blackbird (Euphagus cvanoceDhalus) and blue-black grassquits (Volatinia jacarina).
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Progress 01/01/87 to 12/30/87
Outputs
Operative temperatures (Te) calculated using meteorological data and measured directly with taxidermic mounts were compared for Brewer's blackbirds (Euphagus cyanocephalus) and blue-black grassqiuts (Volantinia jacarina). Calculated Te averaged somewhat higher than the mount temperatures. High correlation values indicated that taxidermic mount temperatures are comparable to calculated values, with a 95% confidence interval of +/- 0.2 to 0.3 C for the best fit regression line. This study establishes the utility of taxidermic mounts as instruments for assessing Te.
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Progress 01/01/86 to 12/30/86
Outputs
The utility of using painted sphere thermometers rather than taxidermic mounts to measure operative temperature was examined (Walsberg & Weathers 1986). Comparison of data for 4 bird species indicates that metal sphere thermometers are acceptable for analyses involving multiple measurements over moderately long time scales (e.g. several hours), but can produce discrepancies of up to 6.3 C during short-term measurements. Heat transfer theory, together with cinematographic analysis, revealed that the peculiar courtship display of the blue-black grassquit facilitates convective heat transfer, thereby allowing this tropical species to extend its display bout duration (Weathers 1986). Simultaneous measurements of daily energy expenditure (DEE) by doubly labeled water and time-budget analysis (Buttemer et al. 1986) revealed that existing time budget models produce erroneous DEE estimates. Measurement of activity costs at the time of study and their subsequent evaluation
through existing heat-transfer theory were shown to be equally important to determining reliable energy budgets.
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Progress 01/01/85 to 12/30/85
Outputs
The energy requirements of canaries incubating different numbers of eggs were determined with an open-circuit respirometer. At temperatures below the thermal neutral zone, canaries consumed more oxygen when incubating than when perched outside of the nest. Oxygen consumption of incubating birds increased with decreasing air temperature by a constant fraction over that of perched birds, averaging about 6% for 2-egg clutches and 19% for 4- to 5- egg clutches. The lower critical temperature was 1.5 to 4.5 C higher in incubating birds. The rate of carbor dioxide production and water flux was determined in free-living nestling house finches using doubly labeled water. Labeled nestlings (mean mass 15.0 g; n=11) produced 4.17 +/ 0.15 ml CO2/(g h) which is equivalent to about 37 kJ/day for a mixed seed diet. Mean water flux was 343.3 +/ 11.6 ml water/(kg day), or about 42% of the total body water pool per day. The data were used to estimate the additional energy needs of
adults feeding nestlings of this size.
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Progress 01/01/84 to 12/30/84
Outputs
Daily energy expenditures (DEE) of aviary-housed budgerygahs (Melopsittacus undulatus) were estimated simultaneously using double-labeled water (DLW) and time-budget (TB) methods under summer and winter conditions. Labortory validation of the DLW technique displayed excellent agreement with concommitant gravimetric measures of CO(2) production (algebraic mean difference = -0.04%; range = -5.2 to 6.2%). The aviary studies combined continuous 24-hour recording of each bird's daily activities with quanitification of its thermal environment (wind speed, air and operative temperatures). Activity and thermoregulatory costs of birds used for TB studies were measured in the laboratory. Comparison of DEE's predicted by DLW to values by the TB method indicate that measurement of activity costs at the time of the study and their subsequent evaluation through existing heat-transfer models are equally important to achieve reliable energy budgets. Avain TB studies that fail to
address these concerns are prone to systematic biases in their estimates of DEE.
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Progress 01/01/83 to 12/30/83
Outputs
We used the doubly labeled water (DLW) technique to measure the daily energy expenditure (H(TD)) of aviary-housed Loggerhead Shrikes (Lanius ludovicianus). Simultaneous to our DLW measurements, we obtained a continuous 24-h record of the birds time budget (TB) and assessed its thermal environment at 10-min intervals with an array of 23 meteorological sensors that measured the air temperature (T(a)), operative temperature (T(e)), and wind speed (u) experienced by the bird. From the TB and meterological data, we estimated the birds' H(TD) by several TB models that differed in the energy equivalents assigned to behaviors in how thermoregulatory costs were calculated. Only a convection-adjusted electrical-analog model proved a mean H(TD) estimate that was identical to the mean DLW value (106kJ/d). Values of H(TD) for individual birds calculated by this model ranged from -8.1 to +7.5% of the DLW values and were significantly correlated with DLW values, indicating that
this method accurately gauged the H(TD) of individual birds. Our analysis showed that this model's accuracy resulted from (1) using T(e) and u to calculate thermoregulatory costs through heat transfer theory, and (2) using measured energy equivalents for the various behavior categories. H(TD) estimates based on other commonly used TB models differed significantly from the DLW values, with mean errors ranging from -18 to +21%.
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Progress 01/01/82 to 12/30/82
Outputs
This year we developed the methods for measuring CO(2) production and water fluxof free-living birds by doubly labeled water (HTO-18). The analysis involves injecting birds with HTO-18, collecting initial blood samples, releasing the bird, recapturing it 1-2 days later, and collecting final blood samples. The blood samples are micro-distilled to obtain pure water, which is assayed for tritium activity by liquid scintillation and for oxygen-18 content by cyclotron-generated proton activation of 0-18 to fluorine-18 with subsequent counting of the gamma-emitting F-18 in a Packard 5,310 gamma counter. We have demonstrated that the method works and are now doing calibration trials.
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Progress 01/01/81 to 12/30/81
Outputs
Estimating energy flow through populations of wild birds requires knowledge of the population size. This frequently is determined from strip-transect censuses. Typically, censuses are limited to early morning, when birds are most active. This greatly reduces the number of censuses that can be made per day. We censused two desert habitats, woodland and scrubland, twice daily - once around sunrise and again at midday - ten times each. In desert scrubland, sunrise and midday strip transect censuses produced comparable estimates of species diversity, species richness, and density. In desert woodland, species diversity averaged 6.3% higher and density 17.4% lower at sunrise than midday. Lower sunrise density in the desert woodland resulted from about half the resident Gambel`s Quail, Mourning Doves and House Finches leaving this habitat at dawn to drink at nearby water sources. Thus, in our study area restricting censusing to around sunrise is inappropriate in the
desert woodland and unnessary in the desert scrubland. In open desert habitats density can be adequately determined from a single census, but reliable estimates of species diversity and richness require 4-5 censuses.
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