Northern Prairie Wildlife Research Center
Population Energetics of Northern Pintails
Wintering in the Sacramento Valley, California
by Michael R. Miller1 and Wesley E. Newton2
Abstract: Recovery of northern pintail (Anas acuta) breeding
populations may be facilitated by improved management of winter food and habitat
resources. We estimated daily energy expenditure (DEE) of pintails, which included
energy required from food and carcass reserves (DERfood, DERreserves),
from mid-August to mid-March during a dry (1980-81) and a wet (1981-82) winter
in the Sacramento Valley, California, using equations for existence metabolism
(EM; kJ/day) and estimates of body mass, carcass composition, food habits, and
apparent metabolizable energy (AME) of winter foods. We used these values and
food density (kg/ha) to model population food and habitat (ha) requirements.
Predicted DEE by monthly period ranged from 794 to 1,180 kJ/day for males and
700 to 1,044 kJ/day for females. Pintails consumed a predicted 49-82 g of food/day
from wetlands and rice fields. The DEE was highest in September-October or October-November
and again in January-February, and DERreserves was greater during
November-December or December-January (up to 11.6% of DEE), and during the dry
winter. Total food consumed by the larger pintail population present in the
wet winter of 1981-82 exceeded that of the smaller population in the dry winter
of 1980-81, both from wetlands (2.89 vs. 2.52 million kg) and harvested rice
fields (11.4 vs. 9.37 million kg). Likewise, the cumulative area of wetlands
and rice fields used to provide food was greater in the wet (2060 ha of wetlands,
41,456 ha of rice fields) than in dry winter (1,782 ha of wetlands, 33,941 ha
of rice fields); these totals accounted for up to 23% of available rice fields
and 9% of available wetlands. Population food and habitat requirements peaked
in December-January, coinciding with peak pintail populations but not peak DEE
(Jan-Feb). Model outcomes were most sensitive to variation in food density,
AME, percentage of food obtained from wetlands and rice fields, and pintail
abundance. Food and habitat seemed adequate for pintail populations wintering
in the Sacramento Valley in the 1980s and presently; however, this conclusion
must be validated by modeling bioenergetic requirements for other abundant waterfowl
and wildlife that forage in rice fields and wetlands in this region.
Key words: Anas acuta, bioenergetics, California, food,
northern pintail, populations, rice, Sacramento Valley, wetlands, winter.
This resource is based on the following source (Northern Prairie Publication
1067):
Miller, Michael R. and Wesley E. Newton. 1999. Population Energetics
of Northern Pintails Wintering in the Sacramento Valley, California.
Journal of Wildlife Management 63(4):1222-1238.
This resource should be cited as:
Miller, Michael R. and Wesley E. Newton. 1999. Population Energetics
of Northern Pintails Wintering in the Sacramento Valley, California.
Journal of Wildlife Management 63(4):1222-1238. Jamestown, ND:
Northern Prairie Wildlife Research Center Online.
http://www.npwrc.usgs.gov/resource/birds/popnrg/popcnrg.htm
(Version 17FEB2000).
Table of Contents
- Introduction
- Study Area
- Methods
- Population Energetics Model
- Calculation of Existence Metabolism
- Adjusting Existence Metabolism
- Energy Content of Composite Diets
- Population Food Requirements
- Statistical Analysis
- Results
- Daily Energy Expenditure
- Daily Food Intake
- Population Food Intake
- Foraging Habitat Required
- Sensitivity Analyses
- Discussion
- Daily Energy Expenditure
- Population Food and Habitat Requirements
- Management Implications
- Acknowledgments
- Literature Cited
- Appendix A -- Mean ambient temperatures, body
mass, and changes in body mass, fat, and protein content of adult male and
female pintails.
Tables and Figures
- Table 1 -- Daily energy expenditures, daily energy
required from body reserves, daily energy obtained from food, and food intake
of individual adult male and female pintails.
- Table 2 -- Mean daily populations and total and
period use-days, estimated food intake, and habitat requirements of adult
male and female pintails.
- Figure 1 -- Daily energy expenditure, daily
energy required from food, and daily energy required from body reserves.
- Figure 2 -- Energy cost for fat synthesis
during periods of body mass gain, and energy contributed by catabolism of
fat during periods of body mass loss.
- Figure 3 -- Patterns of individual and
population food intake of adult northern pintails by monthly periods.
- Figure 4 -- Patterns of population food
intake and hectares of foraging habitat required by monthly periods.
- Figure 5 -- Percent change in area of wetlands
and rice required by adult pintails to support daily energy expenditure.
- Figure 6 -- Area of wetlands and rice required
by adult northern pintails to support daily energy expenditure when pintail
use-days were held constant.
- Figure 7 -- Area of wetlands and rice required
by adult northern pintails to support daily energy expenditure when food
density was held constant.
1 U.S. Geological Survey, Biological Resources Division, Western
Ecological Research Center, Dixon Field Station, 6924 Tremont Road, Dixon, CA
95620, USA. E-mail: michael_r_miller@usgs.gov
2 U.S. Geological Survey, Northern Prairie Wildlife Research Center,
8711 37th Street SE, Jamestown, ND 58401, USA
Downloading Instructions
-- Instructions on downloading and extracting files from this site.
popnrg.zip( 90K) -- Population Energetics of Northern Pintails Wintering in
the Sacramento Valley, California
Installation: Extract all files and open
index.htm in a web browser.
U.S. Department of the Interior |
U.S. Geological Survey