Authors: Tim Birkhead
4
. Best (
2005
).
5
. Henry (
1903
).
6
. Merton et al. (
1984
).
7
. Brumm (
2009
).
8
. Cole (
1944
:
433
).
9
. Pumphrey (
1948
:
194
).
10
. Thorpe (
1961
); Marler and Slabbekoorn (
2004
).
11
. Intriguingly, in the present context, the term ‘pinna’ means feather, although the link with the mammalian ear is unclear.
12
. An interesting exception is the woodcock
Scolopax
spp., whose ear opening lies below, but well in front of, the eye, possibly because so much space is taken up by their huge eyes, and this is the only position possible.
13
. The ear coverts have a shiny appearance because these feathers lack the normal barbules, the tiny hooks that hold the filaments of other feathers together.
14
. Sade et al. (
2008
).
15
.
http://www.nzetc.org/tm/scholarly/tei-Bio23Tuat01-t1-body-d4.html
16
. Cole (
1944
:
111
) makes the same point in criticising the limitations of Hieronymus Fabricius’s seventeenth-century account of the ear: ‘Neither did it occur to him [Fabricius] that the pinna might be a new formation characteristic in mammals. Whilst therefore it would be legitimate to enquire into the causes of its disappearance in some mammals, there was no occasion to attempt to explain its absence in birds, reptiles and fishes, where it had never existed.’
17
. Saunders et al. (
2000
), cited in Marler and Slabbekoorn (
2004
:
207
).
18
. Bob Dooling, personal communication.
19
. Pumphrey (
1948
).
20
. Walsh et al. (
2009
).
21
. White (
1789
).
22
. Dooling et al. (
2000
).
23
. Lucas (
2007
).
24
. Hultcrantz et al. (
2006
); Collins (
2000
).
25
. Dooling et al. (
2000
).
26
. Marler (
1959
).
27
. Tryon (
1943
).
28
. Mikkola (
1983
).
29
. Konishi (
1973
): the facial disc improves sound gathering by about ten decibels.
30
. Pumphrey (
1948
); Payne (
1971
); Konishi (
1973
).
31
. Konishi (
1973
).
32
. Konishi (
1973
).
33
. Hulse et al. (
1997
).
34
. Morton (
1975
).
35
. Handford and Nottebohm (
1976
).
36
. Hunter and Krebs (
1979
).
37
. Slabbekoorn and Peet (
2003
); Brumm (
2004
); Mockford and Marshall (
2009
).
38
. Naguib (
1995
).
39
. Ansley (
1954
).
40
. Vallet et al. (
1997
); Draganuoi et al. (
2002
).
41
. Dijkgraaf (
1960
).
42
. Griffin (
1958
).
43
. Galambos (
1942
).
44
. Some bat species can hear higher frequencies: the tiny Percival’s trident bat,
Cloeotis percivali
(it weighs just four grams), can hear frequencies of
200
kHz (Fenton and Bell,
1981
).
45
. Griffin (
1976
).
46
. Humboldt, quoted in Griffin (
1958
:
279
).
47
. Griffin (
1958
).
48
. Griffin (
1958
:
289
; see also Konishi and Knudsen,
1979
) – Griffin must have made an error: the frequency is about two kilohertz.
49
. Griffin (
1958
).
50
. Konishi and Knudsen (
1979
).
51
. Griffin (
1958
:
291
).
52
. Ripley, cited in Griffin (
1958
).
53
. Novick (
1959
).
54
. Pumphrey, in Thomson (
1964
:
358
).
3. TOUCH
1
. Billie may have heard my daughter’s footsteps, but he might also have felt them. Birds have special vibration dectectors in their feet and legs (Schwartzkopff,
1949
), and it may be these that allow birds to sense branches trembling or, worse, to ‘anticipate’ earthquakes.
2
. Our most touch-sensitive regions are our fingertips, lips and, to a lesser extent, our genitalia.
3
. There is not much published on the touch receptors in the bills of small birds, but Herman Berkhoudt (personal communication) tells me that he examined a zebra finch bill and found many touch receptors including (forgive the names) Merkel cell receptors, double-column Merkel cell receptors and many Herbst corpuscles, all indicative of a very sensitive bill tip.
4
. Goujon (
1869
) refers to these as Pacinian corpuscles and they were first discovered in human fingers by Abraham Vater in the
1740
s, but were mistakenly assumed to have been discovered by Filipo Pacini in
1831
and named (by others) in his honour.
5
. Berkhoudt (
1980
).
6
. Goujon (
1869
).
7
. Berkhoudt (
1980
).
8
. The quote is originally from Nathan Cobb (
1859
–
1932
), founder of the study of nematodes.
9
. Berkhoudt (
1980
).
10
. The Royal Society seems to have lost Clayton’s drawing; Nichola Court searched for them on my behalf, but failed to find them. William Paley (
Natural Theology
,
1802
, pp.
128
–
9
) later used Clayton’s information – with an accompanying illustration of his own – as evidence of God’s wisdom. Paley plagiarised Ray’s
Wisdom of God
(
1961
) and William Derham’s
Physico-Theology
(
1713
): Derham had quoted Clayton’s writing and had probably seen his illustrations of the nerves in the duck’s beak.
11
. Berkhoudt (
1980
).
12
. H. Berkhoudt, personal communication.
13
. Krulis (
1978
); Wild (
1990
).
14
. H. Berkhoudt, personal communication. ‘Touch’ is a multi-faceted concept, reflecting the different types of receptors. The simplest are free nerve endings which detect pain and changes in temperature; slightly more complex are Merkel’s tactile cells (which detect pressure); followed by Grandry bodies, which consist of two to four tactile cells and detect movement (velocity); and the lamellated Herbst corpuscles (similar to Vater-Pacinian corpuscles in mammals), which are sensitive to acceleration.
15
. Brooke (
1985
); M. P. Harris had never seen guillemot allopreening result in the removal a tick, and even the addition of false ticks didn’t elicit allopreening (M. P. Harris, personal communication).
16
. Radford (
2008
).
17
. Stowe et al. (
2008
).
18
. Senevirante and Jones (
2008
).
19
. Carvell and Simmons (
1990
).
20
. Thomson (
1964
).
21
. Pfeffer (
1952
); Necker (
1985
). The receptors associated with filoplumes, together with the numerous other touch receptors in a bird’s skin, are also incredibly important in keeping the plumage sleek when the bird is flying. Indeed, birds have more touch receptors in their skin than mammals; and flying birds have more receptors per unit area than flightless birds, suggesting that they play a crucial role in flight (Homberger and de Silva,
2000
).
22
. Senevirante and Jones (
2010
).
23
. They are also able to detect prey by smell and taste (see chapters
4
and
5
); see also Gerritsen et al. (
1983
).