To Herr Heinrich Klaus Fritz von Gatke,
German Bight Bird Observatory,
British Overseas Territory of German Bight
Very many thanks for your swift missive prompted by my enquiry regarding the increasing numbers of Pendulous Tit-mice appearing in southern England in the late autumn and early winter months. Although I had hoped these records might give muscled body to the airy thought they could become an addition to our avifauna here, now that you have expanded your theories on migration I think I will support with your considered opinions.
I am afraid I have been unable to translate 'zugunruhe' easily, as it appears literally as 'migratory restlessness'. If I have understood you correctly, this is a subjective measure of the sum of all the wonderful influences you and young Berthold are suggesting drives a bird onwards in season? I think I have translated correctly that a young passerine has a 'juvenile' period when it changes from juvenile to juvenile/adult (or full adult) plumage. During this time it appears that it wanders, seemingly without aim, whereas it is in fact this gives opportunity to find breeding possibilities if it makes it returns to our shore in the spring. Adolescent 'hormones' as you call them, have made it wander. One day Listershire, the next South Saxon, the next the Northern Marshes.
Then comes the build of zugunruhe, or migratory restlessness. The true urge to travel a great distance, the urge to follow an inherited migratory track like parents before. It rises like sap, slowly, then a rush, then slowing to bring it to close to parental wintering grounds, if God's will has been done. In the spring, to reverse the journey, the same slow start, mad rush and petering out near 'home' brings a surviving young back close to potential breeding sites.
So, when Pendulous Tit-mice turn up here in late autumn/early winter and loiter in our reed litter they are at the decline or even the halt of their zugunruhe. Unless we clip their wings they will not stay to breed. The sap will rise again.
So those who keep commenting they must surely breed soon on this evidence alone are wrong. All those dreaming of other fanciful migrant passerines such as Bluethroat must also hold their collective breaths as well. The English Channel keeps out both invasive Frenchmen and surly youthful migrants, whose zugunruhe is not strong enough to take on the water, and whose zugunruhe when becoming strong enough to drive them towards darkest Africa, will not lead them in our direction. And if we see them in spring, these are vikings, merely refuelling before driving further? The swarthy Bluethroats of Calais will have 'switched off' as they reach the area and cocked a snoot at La Manche(!)
This is marvellous detective work Klaus(!) Truly, you are revealing God's mechanisms.
I note you then infer as a rule the wanderings of many larger non-passerines are somewhat different to small migrant passerines, and that their size they might take on water crossings? Your suggestion is there is much more chance major British rarities such as Little Egret, Purple Heron, Great White Egret, Night Heron, Cattle Egret and Little Bittern could one day breed here in Albion? Because our watery marshes are within reach of their young? This is most fanciful(!) How I would love it to be so, it would be a great boost for our millinery trade, but perhaps not in this old cleric's lifetime..
Providing this mooted 'Heligoland-Zanzibar' treaty does not pass, and your island remains British through and through, I should very much like to visit one day and instruct you and your colleagues how British ornithologists carry out studies. (I have a dream that an Empire of observatories working in harmony throughout Europe should be achievable, if we fall under one leader.) I know one of my choristers, Gagnell, would like to accompany me; he is trying to record 500 species in Great Britain-ish, and some of your records are mouth-watering.
In the meantime please pass my regards to your friend the Kaiser, and let him know there will be a warm welcome with cakes and tea, should he ever wish to roll into the village of Much Ticking in Listershire.
Your new friend,