P. 38
“It is recent calamitous declines in insect populations, largely driven by agricultural intensification with its widespread use of synthetic pesticides, that have posed the most serious threat to this insectivorous bird (nightjars). It is estimated that more than 40% of all insect species across large swathes of Western Europe are in rapid decline, with a third of insect species threatened with extinction. Within Europe and North America, the UK currently shows the highest rate of insect declines, with a shocking 60% of species documented as being in decline. At least 337 moth species in England – a crucial prey species for the nightjar – have showing declining populations of 12% every 10 years. In the south of England, where nightjars are most concentrated, these moth species are declining at an even faster rate of 17% per decade.”
P. 86 It was thought for some time that dippers, after they dived and reached the bottom, would walk along the riverbed, headfirst into the current … Dippers can move along the riverbed but, crucially, they only do so with the aid of their wings. And there is no evidence that dippers possess a denser mass than the equivalent volume of water … move underwater, and stay submerged, with the aid of their short, powerful wings. P. 87 They use these to propel them through the water, not unlike the way that a penguin uses its winds to swim. The dipper doesn’t fully extend its wings underwater, as they are not sufficiently rigid (unlike the penguin’s , having dispensed of its flight feathers) to form an efficiency surface of resistance for propulsion through water. Instead, the dipper partly extends its wings so that the more rigid parts, around the bone and the firmer sections of the outer primaries, serve to resist the water. The downward tilt of the anterior edge of the dipper’s wings helps to move the bird towards the riverbed, while the backwards sweep of the wings propels the dipper through the water.”
P. 153 Ravens “The nest is lined with a bedding usually wool or hair, which helps keep the egg and chicks warm. Female ravens have been observed tenderly arranging this lining around very young chicks for the hatchling’s comfort, and also burying the nestlings deep in the wool’s warmth in cold weather. Similarly, when the temperature becomes too hot, the female will sometimes bore a hole through the bottom of the nest to increase ventilation. In hot weather the female raven has even been observed to wet her underparts in a stream or pool, then fly to the nest to fool her young with her damp feathers. When egg collecting was rife, ravens who’d had their nests robbed were sometimes observed to have torn out the wool lining so that it was strewn around the side of the nest, as though the birds had been searching through the wool for their eggs in desperation.”
P. 127 “There is some fascinating research that complements this notion that it is the period of singing during level flight. The apex of the (sky)lark’s flight – that conveys most information about the lark’s fitness. A study that looked at the relationship between the skylarks and one of their principal avian predators, the Merlin (the bird capable of prompting a lark to seek shelter next to people) showed that the skylarks will sing in order to evade a Merlin. It is a striking thought: the larks sing, literally, to survive. Merlins will often pursue skylarks in flights for several minutes. So a skylark that sings vigorously and complexly, while having a merlin hot on its tail, in informing the merlin that it is fit and has the stamina to fly higher and faster still. Rather than expend unnecessary energy on the pursuit, the merlin takes the decision to give up on that particular individual: both merlin and skylark benefit from this communication exchange… The study showed that singing skylarks, both male and female – escaped merlin attacks more frequently than non-singing.”
P. 166 A study in Switzerland, published in 2002, that recorded ravens in an area of 1,000km2, found an amazing 79 different call types being used among a sample of 74 ravens, with some of these calls found to be specific to individuals, some to the sex of the bird and some to the specific geographical area. As with skylarks, the greater the distance between raven territories… he fewer call types were shared between birds, and there was a notable geographic boundary in the study as across which call types were less frequently shared. Interestingly, those ravens that occupied territories along this boundary tended to be ‘bilungual’. Established raven pairs will sometimes communicate using their own personal variation of an innate call … if one of the raven pair becomes lost or separated from the other, the remaining bird will call to its lost mate using a call phrase that its partner, rather than itself, habitually used. It is an intriguing and moving gesture; by adopting its partner voice, the remaining bird seems almost to be articulating its sense of loss: I have lost you, the sound of you.”
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