..., to calculate the ground speeds and airspeeds at which a gull is expected to flap or soar during foraging flight. The model results are compared with observed flight speeds, directions, and flight strategies of two species of gulls, the black-headed gull Larus ridibundus and the lesser black-backed gull Larus...

... apply to black-headed gulls ( Larus ridibundus ). Previous experiments have shown that chicks benefit from these higher levels since their competitive abilities are improved and growth and survival probabilities thus enhanced. However, not all females show the same increase in yolk hormones from first...