A comparison of flight energetics in hirundines
and other birds.
will be on their way south later this month, but the swifts have already started their journeys to Africa.
17,18) For example, falcons, hirundines
(Hirundinidae), and seabirds have a high aspect ratio (narrow and elongated wings) and high wing loading (high weight for a low surface), whereas vultures, storks (Ciconiidae), and other land-soaring birds have a low aspect ratio (broad and short wings) and low wing loading (Fig 2).
Bill shapes are often at significant odds with reality, colors frequently range from far too gaudy (most tinamous and pigeons, for example) to the opposite extreme, and all species are shown perched, even seabirds, swifts, and hirundines
Don Wilson watched hirundines
and swifts over Crosby Marine Lake, and a wheatear, presumably a Greenland.
It is barely a week since I was watching swallows hawking low over cold grey water in a biting easterly at Marshside - I felt sorry for the poor hirundines
as they struggled to find food.
Just like home, the kite was elusive - but fortunately more marsh harriers, hirundines
and a hobby meant there was enough to watch until the black kite made an appearance, flapping up onto a telegraph pole to spread its wings like a cormorant, drenched after yet more heavy rain.
Both birds coincided with a period of heavy cloud and a clear passage of swifts and hirundines
Garden warbler, lesser whitethroat, pied and spotted flycatchers, dashing whinchats and squadrons of hirundines
had all quickened the blood during dawn sorties on preceding days.
The 'migration hot-spot' award this week goes to Hilbre on Sunday (April 17), when woodlark, Lapland bunting, yellow wagtail and little tern were joined by two tree pipit and 35 little gulls during an impressive session, on a day when much of the region struggled to provide passage of anything other than a few hirundines
The sand martin is our smallest and most easily overlooked hirundine