Das Verhalten der Feldlerche - KOPS

Summary
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A population of individually marked Skylarks was studied over four
breeding seasons in Ravenglass, Cumberland, England.
The spring arrival of the Skylarks in the study area is described. The S?S?
arrive one month after the cf cf. The arrival is weather dependant.
During the breeding season the Skylark pairs restrict their activity to
territories; characteristics of the latter are described. The relationship betwecn
territory size and population density is discussed. The Skylark's tendency
to return to previous territories is quantitatively described. One year old
Skylarks tend to settle in the neighbourhood of their birthplace. About 10 %
of the population remain without territories.
3 types of song are described: the aerial song, given while circling over
the territory, the ground song, given in a number of postures and the pursuit
song. The yearly cycle of song is discussed. The frequency and length of the
aerial song of the cf cf is greater during pair formation and during the incubation
by the S?; length and frequency do not vary with time of day.
I t is probable that the frequency of ground song shows peaks in the morning
and in the evening. Weather affects song production. The relationship between
the duration of aerial song bouts and the pauses between them is described.
The S?S? only sing occasionally during the pairing and the nestbuilding phase.
The Skylarks have a number of agonistic postures and these are mainly used
in territorial fights. Those which are predominantly aggressive are partially
ritualized, those with high escape tendency less so. The fights do not lead to
serious injuries. The tendency to attack or flee is largely determined by
nearness to the Own territory. The agonistic behaviour fits weH with MOYNIHAN'S
motivation theory if an additional dimension is added i.e. the tendency to fly.
The cf cf are involved in about 4 tim es as many fights as the S?S? Both sexes
tend to attack birds of their own sex.
Skylarks only occasionally engage in interspecific fights, although their
territories usually overlap with those of other songbirds. But when interspecific
fights do occur, the Skylark behaviour is similar to that shown in
intraspecific fights. Birds of prey flying overhead cause the Skylarks to freeze
or to crouch but some cf cf in song flight climbed higher. Only incubating or
birds caring for young reacted to crows approaching the nest. Predatory
malmnals and sitting birds of prey were mobbed communally by the Skylarks.
Incubating S?S? show distraction displays.
Pair formation, which takes place during the first 10 days after the
arrival of the S?S?, is described. It consists mainly of the S?S? settling in the
territories of the cf cf. The apparent loyalty to a mate seems to depend
mainly on this yearly return to the same territory. Monogamy is usual.
Skylarks without territory remain unp ai red but they may pair up later in the
season with widowed larks.
Towards the S?S? the cf cf show a variety of courtship displays, the S?S?,
on the other hand have only one, the copulation soliciting posture. With the
exception of the fluffed posture all courtship displays of the cf cf are
predominantly shown to their mates. The courtship activity of the cf cf
varies with time of day and is heightened during pair formation and the nestbuilding
phase. There is a positive correlation between courtship frequency
and agonistic activity. The copulation soliciting posture of the S? is strictly
linked with nestbuilding. Between the members of a pair there is no dominance
relationship. Amongst other things, the nearness of the S? and the
time of day influence the crest raising of the cf.