Cuckoo migration (Private Passions 6/8/17)

[LeMartinPecheur]

Was anyone else gobsmacked last week hearing about how the English cuckoo is in steep decline while the Scottish one isn't? Satellite tracking has revealed why. Cuckoos apparently migrate in winter to forests in central Africa. English cuckoos go via Spain then cross the Med and the Sahara, and these days they aren't picking up enough body fat in Spain to cross the ever-widening, ever-hotter Sahara. But Scottish cuckoos go via Italy and have a much easier route to where they wanna be for the winter.

Fair enough, English cuckoos are stupid, or need a classier travel agent, to avoid Darwinian consequences.

I shared this with a twitcher colleague at work who hadn't heard it. He pointed out the fascinating question: How do cuckoos know where they're supposed to be going anyway, and by what route, with no parent around to guide them??

Possibly relevant from somewhere else: Originally Posted by Serial_ApologistBut surely that in turn begs the question as to whether forms are any more or less "instinctive" than the means of articulation (speech, music etc) which frame them. The potential for articulation is mostly inborn, (mostly apart from in some brain damaged), but it has to have the framework, whether that's gramar, syntax or musical means, to be enabled. Those frameworks evolve culturally and historically alongside the evolving brain, wouldn't one say? - rendering any separation of "the instinctive" from the arena within which the human capacities express themselves undialectical (for want of a better word!)

PS. OOPS, the relevant Private Passions was last Sun, 6 Aug Hosts, please amend thread title??

[Richard Tarleton]

Fair enough, English cuckoos are stupid, or need a classier travel agent, to avoid Darwinian consequences.

I shared this with a twitcher colleague at work who hadn't heard it. He pointed out the fascinating question: How do cuckoos know where they're supposed to be going anyway, and by what route, with no parent around to guide them??

This is well known - the majority of migrant birds are capable of making their migrations as young and inexperienced birds without the benefit of earlier generations to guide them. Even geese, which do migrate as family parties, are able to migrate successfully by themselves as juveniles. It's genetic, in a word. There's been quite a bit of experimentation under controlled conditions to examine this. Chris Mead's 1983 book Bird Migration a simple starting point. As with other genetic changes over the generations, birds are able to make small changes characterised as "migratory restlessness", those who choose a better route survive to breed whereas those who stick to the old route do not. In some cases of different routes being taken by members of the same species, this can be down to different populations of the same species having evolved separately - for example (whitethroats) through populations having split as a result of glaciation 10-100,000 years ago.

Is your friend really a twitcher? Because he should know all about this. This is how we end up, in autumn, with a select handful of rare migrants from central and eastern Asia, almost invariably juveniles whose genetical programming is faulty and who have set off in 180' the wrong direction - lanceolated warblers, and the like.

[LeMartinPecheur]

Thanks Richard - I shall pass on your message to my colleague, suitably edited.

He's an ex-policeman and a wildlife photographer of considerable local reputation. Birds are his main thing and he knows enough to tell me a lot I don't know, which admittedly on the bird front isn't terribly difficult

Is there a now a degree or NVQ you have to pass to qualify as a twitcher?

[Richard Tarleton]

Thanks Richard - I shall pass on your message to my colleague, suitably edited.

Is there a now a degree or NVQ you have to pass to qualify as a twitcher?

"Twitchers" are the fanatical rarity hunters, who will travel huge distances and be prepared to stand in serried ranks staring at some unfortunate lost bird.... He sounds more of a bird-watcher, or possibly a birder, to me! (All these terms are explained by Bill Oddie in the Little Black Bird Book - I'm a birder.)

Bill Oddie actually does have a short test paper to see which you are. For example:

Place the following in order of importance:

1. Food
2. World peace
3. A lanceolated warbler.

Migration has evolved over millions of years - individuals of species X once decided to spend the winter in a place other than where they bred - driven perhaps by climate, or food supply....They pass this practice on to their progeny, who are more successful than those who stayed put.... It's all about finding the best possible strategy for passing on your genes. To take two superficially similar, closely related species - stonechat and whinchat - one adopts the strategy of staying put, starting to breed early in the season and rearing up to 3 broods. The other spends the winter in sub-Saharan Africa, gambling everything on a dangerous migration, late arrival and a single brood. Both strategies work for them. Cuckoos' evolutionary strategies are more extraordinary than most (there was another good prog about them the other day).

[LeMartinPecheur]

Thanks Richard, clearly my fault for using technical terms I thought I understood but didn't! Not for the first time even here on this board, no doubt