Sorry, not so 'recent' anymore.....

Song of urban-based birds   Siskins and Crossbills

Urban-based birds 'learn to rap'

Dutch researchers found that urban species of birds sing short, fast songs rather than the slower melodies of countryside birds. City birds also sing at a higher pitch and will try out different song types. Experts said city birds have adapted to counter background noise and increase their chances of finding a mate.

Varied songs

The research focused on great tits in ten major European cities, including London, Paris, Amsterdam and Prague, and compared them to forest-dwellers. In every comparison city birds sang a more varied array of songs, which were short and had higher minimum frequencies. Urban tits consistently experimented with between one and five note calls, while those in forests close to the cities stuck to more normal combinations of two, three and four note tunes, the research found. The study even gives the example of one Rotterdam great tit attempting a 16-note song, possibly copied from a blue tit.

Territory

The study, by a team of researchers from the University of Leiden in the Netherlands, is the first to establish a Europe-wide pattern of diverging birdsong. Study leaders said birds had developed shorter, more varied, higher pitched sounds to make themselves heard above trains, aircraft and road traffic. Male birds use their song to mark their territory. If their song is not heard they may come face to face with rivals and end up having to fight them off, the experts said.

Attracting females

They also use song to attract mates and have had to adapt to make sure they are heard by females. The research paper, published in the journal Current Biology, said: "Our data show that the adjustment of individual great tits to local noise conditions is not a local phenomenon but occurs throughout Europe and probably in all noisy urban areas. It went on: "Urban birds often experience very noisy conditions while singing, which may influence the efficacy of their acoustic signals. "Male birds typically sing to defend a territory and to attract mates. "If their song is not heard by the targeted audience they have to physically fight off intruders, and attracting females may be difficult."
From: BBC-news, 5-12-2006

Siskins and Crossbills

The invasion of Two barred Crossbills in the Netherlands the winter of 1998 has given many of us here the chance to familiarize ourselves with the calls of this otherwise very difficult to see species. I have been lucky enough to succeed in making some good recordings of all the main vocalizations including the song and I certainly think I would recognize one in future years if I heard one. Most of the birds seen this winter have been in the vicinity of larches, of which there are none in the Kennemerduinen, my own 'patch' along the coast which I visit regularly, and where there have been considerable numbers of other Crossbills including one Parrot Crossbill (in fact, I already saw juvenile Crossbills a week ago!). In spite of the 150 or so Two barred Crossbills that have been reported up to now in the rest of the country there have been none on this site and because it contains pines rather than larches I wouldn't really expect them.

Today, however, I was in for a surprise. I heard a single clear and unmistakable Two barred Crossbill 'trumpet' call which stopped me in my tracks. I started recording and waited to hear more, but there was nothing but the constant sound of the now numerous Chiffchaffs and Willow Warblers and a quietly singing lone Siskin. Listening to the Siskin more carefully however, I recognized the flight calls, excitement calls and begging calls of 'Common' Crossbills in his song and came to the conclusion that the Two barred had also been his work. In the evening I phoned Roy Slaterus who knows the same patch very well and makes bird recordings. He told me that yesterday he had made a recording of a singing Siskin imitating both the redpoll-like flight call and the 'trumpet' calls of a Two barred Crossbill! The two were combined in a series just to remove any doubt that this was in fact what the Siskin was imitating.

Second hand, imitated, rarities can be almost as much fun as the real thing! Last year, between the two of us, Roy and I managed to record Bee eaters, Cetti's Warbler and Gull billed Tern all snatched from the mouths of Marsh Warblers. No doubt we could have 'strung' a few African species if only we knew their calls! I already suspected a few Bee eater species other than the familiar European one...

As far as the Siskin is concerned, the question is: did it learn the call in western Europe during the current invasion of Two barred Crossbills or, more likely, does the current spectacular Siskin invasion have its origin in the same area of the Russian taiga where the Two barred Crossbill occurs? Has anyone else ever heard a Siskin imitate a Two barred Crossbill? Any more stories of second hand rarities? I thought this one was worth the 'bandwidth' to pass on.

good birding,

April 8, 1998 -Magnus Robb - m.s.robb @ wxs.nl 

read more about his recordings on natuur op media