Energy Conservation and the Evolution of Flightlessness in Birds

  title={Energy Conservation and the Evolution of Flightlessness in Birds},
  author={Brian K. McNab},
  journal={The American Naturalist},
  pages={628 - 642}
  • B. McNab
  • Published 1 October 1994
  • Environmental Science
  • The American Naturalist
I examine the hypothesis that energy conservation contributes to the evolution of a flightless condition in birds by comparing the factors that correlate with basal rate of metabolism in kiwis and flighted and flightless rails and ducks. Flightless rails have low basal rates, the level of which decreases with pectoral muscle mass. Kiwis also have low basal rates and small pectoral masses. The small pectoral masses found in flightless grebes, the flightless cormorant, and the flightless parrot… 

The role of wing length in the evolution of avian flightlessness

It is found that for all eight avian families, the flighted species have shorter wing lengths relative to body mass than their sister families, and it is suggested that these increased energetic costs of flying predispose theseAvian families to evolve flightless species.

Flightlessness and the energetic cost of wing molt in a large sea duck.

The energetic costs of replacing flight remiges in female eiders are substantial, although this is not associated with any change in foraging effort, which suggests that female Common Eiders lose mass during wing molt.

Gradual evolution towards flightlessness in steamer ducks *

Flightlessness in birds is the product of changes in suites of characters—including increased body size and reduced anterior limbs—that have evolved repeatedly and independently under similar

High flight costs, but low dive costs, in auks support the biomechanical hypothesis for flightlessness in penguins

The hypothesis that function constrains form in diving birds is supported, and that optimizing wing shape and form for wing-propelled diving leads to such high flight costs that flying ceases to be an option in larger wing- Propelled diving seabirds, including penguins.

Flightless rails endemic to islands have lower energy expenditures and clutch sizes than flighted rails on islands and continents.

  • B. McNabH. Ellis
  • Environmental Science
    Comparative biochemistry and physiology. Part A, Molecular & integrative physiology
  • 2006

Convergent morphological responses to loss of flight in rails (Aves: Rallidae)

Investigating morphological consequences of flightlessness in a bird family where the condition has evolved repeatedly finds that morphological variation was greater among flightless rails than flighted ones, suggesting that relaxation of physiological demands during the transition to flightlessness frees morphological traits to evolve in response to more varied ecological opportunities.

The physiological costs of flight capability in wing-dimorphic crickets

  • A. ZeraSimon Mole
  • Environmental Science, Biology
    Researches on Population Ecology
  • 2006
The data suggest that the energetic cost of flight capability in adults results from biosynthesis of triglyceride flight fuel and flight muscle maintenance but not flight muscle growth.

The relationship between sternum variation and mode of locomotion in birds

This study lays the groundwork for estimating the locomotory abilities of paravian dinosaurs, the ancestors to Neornithes, by highlighting the importance of this critical element for avian flight, and will be useful for future work on the origin of flight along the dinosaur-bird lineage.

A shortening of the manus precedes the attenuation of other wing-bone elements in the evolution of flightlessness in birds

A comparative analysis using phylogenetic independent contrasts showed that in families that contain both flighted (volant) and flightless species, the volant species have shorter wings and total-arm lengths relative to their body masses than the species within their wholly volant sister families.


It is proposed that the reduction in wing size allows the Galapagos Cormorant to be more efficient at shallow depths than other seabirds, but only in warm equatorial waters.




Proportions in the wing skeleton, intraspecific allometry, and limited data on growth indicate that the relatively short wing bones and remiges of flightless Tachyeres are produced developmentally by a delay in the growth of wing components, and that this heterochrony may underlie, in part, skeletal sexual dimorphism.


  • B. Livezey
  • Biology
    Evolution; international journal of organic evolution
  • 1989
Relative wing lengths and conformation of sterna in Rollandia microptera and Podiceps taczanowskii indicate that morphological changes associated with flightlessness are paedomorphic; intraspecific allometry in rollandia indicates that the underlying ontogenetic change may involve a delay in the start of pectoral‐alar development (postdisplacement).

The evolution of flightlessness in insects

  • D. Roff
  • Environmental Science, Biology
  • 1990
It is hypothesized that larval migration by ballooning, the large—scale spatiotemporal stability of woodlands, and the small—scale unpredictability of spring bud burst are primary factors favoring the evolution of flightlessness in these Lepidoptera.


  • K. Nagy
  • Biology, Environmental Science
  • 1987
Field metabolic rates (FMRs or HF), all measured using doubly labeled water, of 23 species of eutherian mammals, 13 species of marsupial mammals, and 25 species of birds were summarized and analyzed

The Relationship of Energetics of Falconiform Birds to Body Mass and Climate

I measured body temperature and resting metabolic rate as a function of ambient temperature in eleven species of falconiforms and found that Falconiforms from hot habitats have lower resting metabolic rates than those from temperate habitats.

Evolution of the rails of the South Atlantic islands (Aves: Rallidae)

  • S. Olson
  • Environmental Science, Biology
  • 1973
Flightlessness in rails is shown to be a neotenic condition that involves only the control of relative growth of body parts, is evolved at a rapid rate, and therefore has limited taxonomic significance.

Morphological corollaries and ecological implications of flightlessness in the kakapo (Psittaciformes: Strigops habroptilus)

  • B. Livezey
  • Environmental Science
    Journal of morphology
  • 1992
The morphological corollaries of flightlessness of the kakapo (Strigops habroptilus) have been studied using skin specimens, skeletons, and pectoral dissection of an anatomical specimen and aspects are compared to those of other flightless birds.

Thermoregulation in fasting emperor penguins under natural conditions.

Emperor penguins breed during the cold antarctic winter; the males incubate the single egg while fasting for up to 4 mo and losing some 20 kg of their body mass, higher than predicted from general metabolic equations for birds.

A new species of rail from the solomon islands and convergent evolution of insular flightlessness

An extant new species of flightless or weak-flying rail from the Solomon islands in the southwest Pacific Ocean, it is suggested that the ancestral species had boldly patterned plumage similar to that of G. philippensis, and that insular reduction of bold pat- terning has proceeded independently in G. rovianae, G. owstoni, and several other G.philippensis derivatives.

The wing musculature of the Brown kiwi Apteryx australis mantelli and its bearing on ratite affinities

The present skeleto-muscular data suggests that ratites are primitive birds that evolved from a primitive, volant ancestor and should be regarded as primitive birds, rather than as advanced birds that evolve from carinates.