Post by accipiter on Apr 14, 2021 17:48:38 GMT
Sparrowhawk behaviour a synopsis
Subtitled - extracts from a diary
Since last time I posted I’ve been very busy recording our little owl behaviour, but as promised I’m reporting back concerning immature Sparrowhawk / adult behaviour, I’ll refer to (first spring birds = second calendar year first.) In point of fact, I seem to remember reporting these facts on the old WAB site from kept notes. So, looking back at my notes in reference to April 15th 2010 they read as the following.
Adult male Sparrowhawk flew low over the house today, finally coming to rest in the top of a tall tree joined by at least five more immature birds flying low in circles overhead, April 15th 2010 12 degree’s 9 15 am cold northeast wind. Given those facts I wouldn’t really expect this behaviour given the time of year and weather conditions being not exactly conducive, nonetheless it’s something I’ve come to expect, (behaviour isn’t set in stone.)
Only today April 14th 2021 there were even more perhaps as many as ten immature Sparrowhawks circling low over buzzard wood, since three pairs nest here quite close together along with common buzzard. Tolerated behaviour such as this by the adult resident Sparrowhawks is related to suitable habitat (size etc.) and the amount of prey therein being very good indeed here all year round a veritable oasis, including little human disturbance; as opposed to many other places I’ve carried out studies where this isn’t the case, simply because just one pair are in residence in which case the resident hen drives all other visiting hens away in a spectacular undulating display flight.
It’s interesting to note some juveniles ( from the same brood) stay pretty much together here right up to December and beyond even seen taking baths together which is not so unusual or remarkable given the above facts and bearing in mind Sparrowhawks also love to bathe; confirming the fact siblings are still able to recognise each other even after time spent wandering from place to place; whilst other juveniles (those left in August / September) return again in late autumn to roost in their natal territory sometimes even very close to the nest, only to leave shortly after. I’ve seen these patterns repeated quite a few times over the years making final dispersal very late in the case of the former as opposed to the month of August / September when dispersal takes place in the majority of cases. Just to make it even more interesting mature birds / floaters arrive here too i.e., those without a mate, identified by plumage markings being slightly different than those adult residents, no doubt attracted by the abundance of prey here.
Nonetheless, early adult display flights take place in mid-March / April I’ve already noted that behaviour here this year as expected, also consisting of what I can only describe as leg dangling by the male whilst in flight, including courtship chases through the trees their white undertail coverts flared as in display. Only to settle on a favoured plucking post in full view of the nest whilst the male does his “hormone driven display dance” in front of the female which may or may not include pecking its own feet. The latter behaviour being something I’ve only witnessed over the last few years even though I’ve been observing their breeding behaviour for many years, strongly suggesting this doesn’t happen in all cases. But interestingly enough these hormone driven episodes sometimes occur in captive bred birds too where food is provided by the austringer adding weight to the fact it’s not connected with the males proficiently at providing food therefor not related to courtship. However, my late brother also mentioned the hormone driven display dance in his study having witnessed this behaviour in March1948 little wind 69 Fahrenheit, exceptionally warm he writes for March witnessed both in the field and in his captive breeding program.
Nonetheless, I found the next entry extremely interesting where he tells of two hens being shot close to a nest containing young (estimated to be three weeks of age) a study in progress since the two hens laid eggs in the nest. However, he persuaded the gamekeeper not to finish the job namely by shooting through the nest thereby destroying the nest and its contents a (common gamekeeper practise) in the hope the male would deliver food to the young in which it did successfully carry out. However, I should say in the normal turn of events only the hen feeds the chicks whilst the male delivers the food.
Interestingly enough, extra pair copulations not only take place in Sparrowhawks but up to ninety percent of all bird species a surprising figure one might say, what’s more it’s thought seventy percent of chicks are not the result of just the one male, the skylark being just one example in which twenty percent of chicks are not genetically related. So, it would seem pair bonded birds may be monogamous but not sexually, to explain what I mean by that take the swan as another example, the very paragon of virtue, (at least it was once thought to be) but thanks to many years of field study and molecular finger printing it’s proved to be quite promiscuous.
I’ve also been in the privileged position where I’ve witnessed polygyny taking place in in three consecutive years a rare occurrence in Sparrowhawks; believe it or not, in these cases one male delivers food to two females. However, (all attempts failed at the egg laying stage) the reason being the male in question could not keep up the amount of food required to feed both hens, hence one breeding attempt failed.
But to return to my brothers’ study of the two hen Sparrowhawks, he clearly makes the point had the chicks been very young therefore unable to control their body temperature and feed their selves the outcome would have been entirely different. Reading on he tells of early breeding doesn’t always produce large clutches something else I’ve recorded too as opposed to what is often written to be the case. In the meantime, I still haven’t had time to read his entire collection of journals but very much looking forward to doing so since it adds up to life time of study of Sparrowhawk behaviour.
I should also add behaviour as described also very much depends on the adult pair themselves since some years I don’t see any displays flights taking place, having spent many years in such a position where I can scan the area including within full view of the nest and plucking post, behaviour I’ve also carried out in many parts of the country as indeed did my late brother in order to achieve the best possible assessment of the species. In such cases the usual food pass (part of the courtship process) takes place at the plucking post which may or not be in full view of the nest. Interestingly enough at the incubation stage some males may deliver the food to the nest as opposed to calling the hen to his plucking post again very much depending on the pair involved since some females will not tolerate this behaviour; whilst others will even allow the male to cover the eggs for a short time while she takes a break up to twenty minutes (something else I’ve recorded.) I should also say times and dates I’ve referred to vary again depending on the pair themselves, including the weather conditions at the time. On a finale note, I’ve found nest number three almost in completion and so the circle of life repeats itself.
Nevertheless, signs are looking good at the moment in reference to my little owls in as much as food is being taken inside the nest boxes, given the present date and absence of the hens I suspect eggs are being laid or indeed incubated, and so field studies continue for the sixth year.
As a footnote the Dunnocks that fledged five last year just a few feet from our kitchens window (Dunnocks are supposed to be shy birds) are now busy relining last year’s nest (apparently no one told them they should build a new one.) Behaviour isn’t set in stone? It would certainly seem so.
So, what could possibly go wrong, on second thoughts where did I leave the creme brulee.
Alan
Subtitled - extracts from a diary
Since last time I posted I’ve been very busy recording our little owl behaviour, but as promised I’m reporting back concerning immature Sparrowhawk / adult behaviour, I’ll refer to (first spring birds = second calendar year first.) In point of fact, I seem to remember reporting these facts on the old WAB site from kept notes. So, looking back at my notes in reference to April 15th 2010 they read as the following.
Adult male Sparrowhawk flew low over the house today, finally coming to rest in the top of a tall tree joined by at least five more immature birds flying low in circles overhead, April 15th 2010 12 degree’s 9 15 am cold northeast wind. Given those facts I wouldn’t really expect this behaviour given the time of year and weather conditions being not exactly conducive, nonetheless it’s something I’ve come to expect, (behaviour isn’t set in stone.)
Only today April 14th 2021 there were even more perhaps as many as ten immature Sparrowhawks circling low over buzzard wood, since three pairs nest here quite close together along with common buzzard. Tolerated behaviour such as this by the adult resident Sparrowhawks is related to suitable habitat (size etc.) and the amount of prey therein being very good indeed here all year round a veritable oasis, including little human disturbance; as opposed to many other places I’ve carried out studies where this isn’t the case, simply because just one pair are in residence in which case the resident hen drives all other visiting hens away in a spectacular undulating display flight.
It’s interesting to note some juveniles ( from the same brood) stay pretty much together here right up to December and beyond even seen taking baths together which is not so unusual or remarkable given the above facts and bearing in mind Sparrowhawks also love to bathe; confirming the fact siblings are still able to recognise each other even after time spent wandering from place to place; whilst other juveniles (those left in August / September) return again in late autumn to roost in their natal territory sometimes even very close to the nest, only to leave shortly after. I’ve seen these patterns repeated quite a few times over the years making final dispersal very late in the case of the former as opposed to the month of August / September when dispersal takes place in the majority of cases. Just to make it even more interesting mature birds / floaters arrive here too i.e., those without a mate, identified by plumage markings being slightly different than those adult residents, no doubt attracted by the abundance of prey here.
Nonetheless, early adult display flights take place in mid-March / April I’ve already noted that behaviour here this year as expected, also consisting of what I can only describe as leg dangling by the male whilst in flight, including courtship chases through the trees their white undertail coverts flared as in display. Only to settle on a favoured plucking post in full view of the nest whilst the male does his “hormone driven display dance” in front of the female which may or may not include pecking its own feet. The latter behaviour being something I’ve only witnessed over the last few years even though I’ve been observing their breeding behaviour for many years, strongly suggesting this doesn’t happen in all cases. But interestingly enough these hormone driven episodes sometimes occur in captive bred birds too where food is provided by the austringer adding weight to the fact it’s not connected with the males proficiently at providing food therefor not related to courtship. However, my late brother also mentioned the hormone driven display dance in his study having witnessed this behaviour in March1948 little wind 69 Fahrenheit, exceptionally warm he writes for March witnessed both in the field and in his captive breeding program.
Nonetheless, I found the next entry extremely interesting where he tells of two hens being shot close to a nest containing young (estimated to be three weeks of age) a study in progress since the two hens laid eggs in the nest. However, he persuaded the gamekeeper not to finish the job namely by shooting through the nest thereby destroying the nest and its contents a (common gamekeeper practise) in the hope the male would deliver food to the young in which it did successfully carry out. However, I should say in the normal turn of events only the hen feeds the chicks whilst the male delivers the food.
Interestingly enough, extra pair copulations not only take place in Sparrowhawks but up to ninety percent of all bird species a surprising figure one might say, what’s more it’s thought seventy percent of chicks are not the result of just the one male, the skylark being just one example in which twenty percent of chicks are not genetically related. So, it would seem pair bonded birds may be monogamous but not sexually, to explain what I mean by that take the swan as another example, the very paragon of virtue, (at least it was once thought to be) but thanks to many years of field study and molecular finger printing it’s proved to be quite promiscuous.
I’ve also been in the privileged position where I’ve witnessed polygyny taking place in in three consecutive years a rare occurrence in Sparrowhawks; believe it or not, in these cases one male delivers food to two females. However, (all attempts failed at the egg laying stage) the reason being the male in question could not keep up the amount of food required to feed both hens, hence one breeding attempt failed.
But to return to my brothers’ study of the two hen Sparrowhawks, he clearly makes the point had the chicks been very young therefore unable to control their body temperature and feed their selves the outcome would have been entirely different. Reading on he tells of early breeding doesn’t always produce large clutches something else I’ve recorded too as opposed to what is often written to be the case. In the meantime, I still haven’t had time to read his entire collection of journals but very much looking forward to doing so since it adds up to life time of study of Sparrowhawk behaviour.
I should also add behaviour as described also very much depends on the adult pair themselves since some years I don’t see any displays flights taking place, having spent many years in such a position where I can scan the area including within full view of the nest and plucking post, behaviour I’ve also carried out in many parts of the country as indeed did my late brother in order to achieve the best possible assessment of the species. In such cases the usual food pass (part of the courtship process) takes place at the plucking post which may or not be in full view of the nest. Interestingly enough at the incubation stage some males may deliver the food to the nest as opposed to calling the hen to his plucking post again very much depending on the pair involved since some females will not tolerate this behaviour; whilst others will even allow the male to cover the eggs for a short time while she takes a break up to twenty minutes (something else I’ve recorded.) I should also say times and dates I’ve referred to vary again depending on the pair themselves, including the weather conditions at the time. On a finale note, I’ve found nest number three almost in completion and so the circle of life repeats itself.
Nevertheless, signs are looking good at the moment in reference to my little owls in as much as food is being taken inside the nest boxes, given the present date and absence of the hens I suspect eggs are being laid or indeed incubated, and so field studies continue for the sixth year.
As a footnote the Dunnocks that fledged five last year just a few feet from our kitchens window (Dunnocks are supposed to be shy birds) are now busy relining last year’s nest (apparently no one told them they should build a new one.) Behaviour isn’t set in stone? It would certainly seem so.
So, what could possibly go wrong, on second thoughts where did I leave the creme brulee.
Alan
