The elaborate plumage in peacocks is not such a drag

May combine two claims.

Because the train is produced over about six months, its production cost is estimated at 96.3 kJ per day, about 10% of basal metabolic rate and 3% of field metabolic rate.

“The train is produced over ~6 months (M.Caunce, personal communication), such that the train production costs are estimated to be 96.3 kJ day -1 , representing ~10% of basal metabolic rate [947 kJ day -1 (Lasiewski and Dawson, 1967)] and 3% of field metabolic rate [2805 kJ day -1 , estimated from a scaling equation for Galliformes (Nagy et al., 1999)].”

• cites M.Caunce, personal communicationNot matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites Lasiewski and Dawson, 1967 sourceSupported
• cites Nagy et al., 1999 sourceNot checked — no full text of the source

May combine two claims.

The train in this study weighed 320 g, giving an estimated production cost of 17.5 MJ.

“The mass of the train in this study was 320 g, giving an estimated cost of producing the train of 17.5 MJ.”

May combine two claims.

Profile power and the power needed to generate induced velocity did not differ significantly between peacocks with and without a train.

“Profile power and the power required to generate the induced velocity were not significantly different between the two conditions (Table 2).”

May combine two claims.

Drag on the train depends on flight velocity and on the angle at which the train is held relative to the bird's flight path.

“The drag on the train depends on flight velocity and the angle at which it is held relative to the flight trajectory of the bird (Fig. 2) (see also Evans and Thomas, 1992).”

• cites Evans and Thomas, 1992 sourceNot checked — no full text of the source

May combine two claims.

Take-off velocity and velocity at the end of the second wingstroke did not differ significantly between peacocks with and without a train.

“The velocity of the bird at take-off and the flight velocity of the peafowl at the end of the second wingstroke were not significantly different between the two treatments (Table 2).”

May combine two claims.

Drag on the peafowl train rose linearly with air velocity at each tested angle and was greatest at steeper angles.

“The drag on the train increased linearly with increasing air velocity for each angle and was highest at steeper angles (Fig. 2).”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

Increasing body mass is expected to raise induced power and thereby reduce flight performance through a decrease in centre-of-mass power.

“Increasing body mass is expected to increase induced power (through increases in thrust and induced velocity), and therefore to decrease flight performance via a reduction in P CoM .”

Classified as probably not a substantial claim.

It is not known whether the recorded flights were maximal.

“Whether these flights were maximal is not known”

May combine two claims.

The high power output and work generated by the flight muscles indicate that the recorded flights were likely very close to maximal and performed with similar effort.

“Together, the high power output and work generated by the flight muscles suggest that the flights obtained for each individual were likely very close to maximal, and performed with a similar level of effort.”

May combine two claims.

The potential costs of the train are not mutually exclusive, each could be subtle and hard to detect, and ultimate fitness costs could arise from their cumulative effect on locomotor performance.

“None of these potential costs are mutually exclusive and all could individually be relatively subtle and difficult to detect: the ultimate fitness costs could be the result of the cumulative effect of each of these factors on locomotor performance.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

Several other sexually selected traits have been reported to have rather subtle effects on bird locomotor performance.

“There are several other examples of sexually selected traits having rather subtle effects on bird locomotor performance.”

Classified as probably not a substantial claim.

Flight performance variables and aerodynamic power components were compared using paired t-tests with Bonferroni-Holm correction for multiple comparisons.

“Flight performance variables and aerodynamic power components were analysed using paired t-tests with significance levels adjusted using the Bonferroni-Holm correction for multiple comparisons.”

Classified as probably not a substantial claim. May combine two claims.

The flights took place in a familiar flight arena using captive-bred birds, conditions that could potentially compromise performance.

“The flights were performed in a flight arena with which the birds were familiar, using captive-bred birds.These are conditions that could potentially compromise performance.”

May combine two claims.

Although added mass must affect induced power requirements, the size of that effect has little meaningful functional relevance given the high variability in individual take-off performance.

“Together, these findings suggest that although added mass must affect the induced power requirements, the magnitude of the effect has little meaningful functional relevance (given the high variability in individual take-off performance per se; Table 2, Fig. 1A) (Macleod, 2006).”

• cites Macleod, 2006 sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S3 (load-bearing).

The flight arena volume was calibrated using the direct linear transformation method.

“The flight arena volume was calibrated using the direct linear transformation method (Hedrick, 2008).”

• cites Hedrick, 2008 sourceNot checked — no full text of the source

Classified as probably not a substantial claim.

For each bird, the flight with the highest centre-of-mass power in each treatment was selected for statistical comparison because differences are most likely to appear during maximal effort.

“For each individual, the flight with the highest P CoM for the two treatments was selected for statistical comparisons, as any potential differences in performance are most likely to be apparent during maximal effort flights.”

Probably not a substantial claim: may not pass S4 (based).

The peacock's train is often cited as a classic example of a costly product of sexual selection.

“The peacock's train is often cited as a classic example of a 'costly' product of sexual selection.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Vertical display flights by collared doves have been estimated to incur a relatively low metabolic cost of about 5% of basal metabolic rate.

“The vertical display flights performed by collared doves (Streptopelia decaocto) have been estimated to incur a relatively low metabolic cost (~5% of basal metabolic rate) (Usherwood, 2008).”

• cites Usherwood, 2008 sourceNot checked — no full text of the source

May combine two claims.

The work output from the flight muscles, 66 J/kg, was close to total mechanical work during take-off in common raven and Harris hawks and close to the maximum work predicted for skeletal muscle.

“The work output from the muscles (66 J kg -1 ) is also close to the total mechanical work required from the muscles during take-off flights in common raven [48 J kg -1 (Jackson and Dial, 2011)] and Harris hawks [56 J kg -1 (Askew et al., 2001)], and close to the maximum work skeletal muscles are predicted to be capable of generating (Peplowski and Marsh, 1997).”

• cites Jackson and Dial, 2011 sourceNot checked — no full text of the source
• cites Askew et al., 2001 sourceNot checked — no full text of the source
• cites Peplowski and Marsh, 1997 sourceNot checked — no full text of the source

May combine two claims.

Any costs of possessing an ornate train are small and have limited meaningful functional significance for take-off performance.

“any such costs are small with limited meaningful functional significance to take-off performance.”