8 Works

The allometry of daily energy expenditure in hummingbirds: an energy budget approach

Anusha Shankar, Donald R Powers, Liliana M Dávalos & Catherine H Graham
1. Within-clade allometric relationships represent standard laws of scaling between energy and size, and their outliers provide new avenues for physiological and ecological research. According to the metabolic level boundaries hypothesis, metabolic rates as a function of mass are expected to scale closer to 0.67 when driven by surface-related processes (e.g., heat or water flux), while volume-related processes (e.g., activity) generate slopes closer to one. 2. In birds, daily energy expenditure (DEE) scales with body...

The Critical Need for Peer Clinical Supervision Among School Counselors

Pamelia E. Brott, Lorraine DeKruyf, Jung Hyun, Christopher LaFever, Sarah Patterson-Mills, Mariama Sandifer & Victoria Stone

Festival Review: 72nd Festival de Cannes

Joel Mayward
Journal of Religion Film and Media, 5(2), 204-213

Data from: Integrating morphology and kinematics in the scaling of hummingbird hovering metabolic rate and efficiency

Derrick J.E. Groom, M. Cecilia B. Toledo, Donald R. Powers, Bret W. Tobalske, , Derrick J. E. Groom & Kenneth C. Welch
Wing kinematics and morphology are influential upon the aerodynamics of flight. However, there is a lack of studies linking these variables to metabolic costs, particularly in the context of morphological adaptation to body size. Furthermore, the conversion efficiency from chemical energy into movement by the muscles (mechanochemical efficiency) scales with mass in terrestrial quadrupeds, but this scaling relationship has not been demonstrated within flying vertebrates. Positive scaling of efficiency with body size may reduce the...

Data from: Three-dimensional simulation for fast forward flight of a calliope hummingbird

Jialei Song, Bret W. Tobalske, Donald R. Powers, Tyson L. Hedrick & Haoxiang Luo
We present a computational study of flapping-wing aerodynamics of a calliope hummingbird (Selasphorus calliope) during fast forward flight. Three-dimensional wing kinematics were incorporated into the model by extracting time-dependent wing position from high-speed videos of the bird flying in a wind tunnel at 8.3 m s−1. The advance ratio, i.e. the ratio between flight speed and average wingtip speed, is around one. An immersed-boundary method was used to simulate flow around the wings and bird...

Data from: Hovering in the heat: effects of environmental temperature on heat regulation in foraging hummingbirds

Donald R. Powers, Kathleen M. Langland, Susan M. Wethington, Sean D. Powers, Catherine H. Graham & Bret W. Tobalske
At high temperature (>40 ºC) endotherms experience reduced passive heat dissipation (radiation, conduction, and convection) and increased reliance on evaporative heat loss. High temperatures challenge flying birds due to heat produced by wing muscles. Hummingbirds depend on flight for foraging, yet inhabit hot regions. We used infrared thermography to explore how lower passive heat dissipation during flight impacts body-heat management in broad-billed (Cynanthus latirostris, 3.0g), black-chinned (Archilochus alexandri, 3.0g), Rivoli’s (Eugenes fulgens, 7.5g), and blue-throated...

Hummingbird torpor in context: duration, more than temperature, is the key to nighttime energy savings

Anusha Shankar, Rebecca J. Schroeder, Susan M. Wethington, Catherine H. Graham & Donald R. Powers
Torpor is an important energy saving strategy in some small birds, but it has rarely been studied in natural field conditions. We compared torpor use across 43 wild-caught individuals of eight hummingbird species across sites with different natural temperature regimes. Most laboratory studies focus on the relationship between metabolic rate and temperature, but our aim was to evaluate what environmental factors most influence hummingbird nighttime energy management under natural conditions. We found that the probability...

A heterothermic spectrum in hummingbirds

Anusha Shankar, Isabelle NH Cisneros, Sarah Thompson, Catherine H Graham & Donald R Powers
Many small endotherms use torpor, saving energy by a controlled reduction of their body temperature and metabolic rate. Some species (e.g. arctic ground squirrels, hummingbirds) enter deep torpor, dropping their body temperatures by 23-37 &[deg]C, while others can only enter shallow torpor (e.g., pigeons, 3-10 &[deg]C reductions). However, deep torpor in mammals can increase predation risk (unless animals are in burrows or caves), inhibit immune function, and result in sleep deprivation, so even for species...

Registration Year

  • 2022
  • 2021
  • 2020
  • 2019
  • 2018
  • 2017
  • 2016

Resource Types

  • Dataset
  • Journal Article
  • Text


  • George Fox University
  • University of Montana
  • Stony Brook University
  • Swiss Federal Institute for Forest, Snow and Landscape Research
  • Columbus State University
  • University of North Carolina
  • University of Alaska Fairbanks
  • Lindenwood University
  • University of Tennessee at Knoxville
  • Seattle Pacific University