Skip to page content
USDA Forest Service

Research & Development Treesearch

Treesearch Home
About Treesearch
Contact Us
Research & Development
Forest Products Lab
International Institute of Tropical Forestry
Pacific Northwest
Pacific Southwest
Rocky Mountain
Southern Research Station
Help - We Participate  Government Made Easy

Global Forest Information Service

US Forest Service
P.O. Box 96090
Washington, D.C.

(202) 205-8333

You are here: Home / Search / Publication Information
Bookmark and Share

Publication Information

View PDF (840 KB)

Title: Parental expenditure of time and energy in the Abert's Towhee (Pipilo aberti)

Author: Finch, Deborah M.;

Date: 1984

Source: The Auk. 101: 473-486.

Publication Series: Miscellaneous Publication

Description: Daily activity budgets of male and female Abert's Towhees (Pipilo aberti) were measured in 1980 during the reproductive cycle and then converted into energy budgets to determine the relative demands of different nesting phases. Mean daily energy expenditures (DEEtot) in males reached a seasonal maximum of 126.7 kJ, or 2.16 times basal metabolic rate (BMR), in the prenesting phase. Thermoregulatory demands accounted for higher energy expenses in this phase. The cost for females was also high in the pre nesting phase but was exceeded by DEEtot in the egg-laying phase. Average DEEtot was at a seasonal minimum of 103.8 kJ, or 1.8 times BMR, in incubating females. Females conserved energy in the incubation phase by minimizing activity, and 78% of the variation of DEEtot in individual females was explained by mean daily air temperature. Activity costs (DEEact) differed significantly between males and females during the incubation phase, but DEEtot did not. Mean DEEact and DEEtot were significantly greater in females during the nestling period than during incubation. DEEact explained 58% of the individual variation in female DEEtot in the nestling phase, whereas air temperature explained only 28% of the variation. Interphasic variation in DEEact was wider in females than males, because females closely tracked offspring requirements by attending at the nest. Males did not incubate or brood, and spare time spent "loafing" tended to minimize DEEact Excluding the egg-laying female, estimates of DEEtot in individual towhees ranged from 1.6 to 2.18 times BMR and compare well with estimates of DEEtot in the Northern Mockingbird (Mimus polyglottos), which is about the same size.

Keywords: Abert's Towhee, Pipilo aberti, daily activity budgets, daily energy expenditures, activity costs

Publication Notes:

  • We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
  • This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
  • You may send email to to request a hard copy of this publication. (Please specify exactly which publication you are requesting and your mailing address.)



Finch, Deborah M. 1984. Parental expenditure of time and energy in the Abert's Towhee (Pipilo aberti). The Auk. 101: 473-486.


 [ Get Acrobat ]  Get the latest version of the Adobe Acrobat reader or Acrobat Reader for Windows with Search and Accessibility

USDA logo which links to the department's national site. Forest Service logo which links to the agency's national site.