born behavour On Sat, Jun 9, 2012 at 3:30 PM, Saurabh Sawant <[email protected]>wrote:
> Ah, yes. We definitely missed out on an obvious one there. > And you read me correctly. This discussion was very insightful. :) > > Regards, > Saurabh > > On Thu, Jun 7, 2012 at 2:58 AM, Hans Peeters <[email protected]> wrote: > >> Dear Saurabh, >> >> Kiran Srivastava mentioned to me that he had seen a treeswift nest some >> time ago and how very difficult it was to find it again each time he >> visited it even though it was right out in the open on a bare tree branch >> at some height. I don't know why you and I hadn't thought of this species >> -- it's well known for its peculiar nest, a tiny minimal cup made of bark >> bits and small feathers glued with saliva to a branch. This type of nest >> nicely supports the recent DNA work that demonstrates the long-held belief >> that treeswifts are closely related to true swifts (Apodidae), which build >> a very similar nest albeit in more sheltered situations. Anyway, the >> treeswift adds one more example to your list of well-camouflaged nests of >> small birds built in bare trees. Still, a very short list, and these >> species are truly exceptions among smallish birds in nest placement. It's >> also interesting that the smallest herons, instead of building their nests >> out in the open as is typical for most members of the family, nest in dense >> bushes and trees. And Cattle egrets, being sort of mid-sized, will nest >> colonially in bare trees but often hide their nests in leafy trees when >> they are breeding as single couples. >> >> I'm not sure I am reading you correctly, but I believe you mean to say >> that birds *do* change their nesting habits because of changes in >> weather, and that is certainly true. The current global warming is >> producing major changes both in North America and in Europe, with many >> birds beginning to breed much earlier in the year than they used to. For >> example, in the Rocky Mountains of the U.S., American Robins (actually a >> large thrush) arrive at their high-altitude breeding grounds two weeks >> earlier from spring migration than they did a few years ago, and go on to >> breed with the result that there is insufficient food for the young. There >> are many examples of range expansion and even of movement into new habitats >> because of weather changes. Birds are very labile when it comes to >> acceptable parameters for breeding; the photoperiod is just a rough >> indicator as shown by a temporary display in autumn of breeding behavior by >> North American birds that does not result in actual breeding because of the >> absence of certain stimuli. It's all very interesting! >> >> Best regards, >> Hans >> >> >> >> >> On Mon, May 28, 2012 at 12:15 AM, Saurabh Sawant < >> [email protected]> wrote: >> >>> Dear Hans, >>> >>> Well, that's exactly my point. That's why I had to mention twice that a >>> question like this has to be very specific for a group of birds or >>> particular species. :) >>> >>> And, I don't know much about nidification of indian birds either >>> despite of the fact that I get to see them everyday. :| >>> >>> Yes, Climate was a wrong choice of word. But I was probably thinking >>> over a longer time and behaviour specific evolution to which the question >>> sounded more related. I wanted to refer to the fact that even if there are >>> changes in weather these birds wouldn't change their habitats or nesting >>> habits by great extents over a short period. Perhaps, for the environmental >>> factors that affect nest building, growth & development of chicks, molting >>> in juveniles and young birds. Eg. Photoperiod >>> >>> Coming to the nests, I completely agree with you that most birds that >>> nest in bare big trees are big enough, especially raptors to defend their >>> nests. The nests themselves are so big that they can use all the extra >>> space that bare trees offer. Also, yes.. they use twigs and sticks for >>> their nests. But, smaller birds that may choose such sites as I said have >>> amazingly well camouflaged nests. Recent ones I observed were Thick-billed >>> Flowerpecker nesting on a bare tree with very few completely dry leaves >>> just drooping. But, it nests in such a beautiful fashion, it takes one time >>> to know it's a nest and not another dry leaf. Another was the Common >>> Woodshrike which was seen nesting on a completely bare tree. It builds nest >>> in shallow forks of horizontal branches and is very well camouflaged. >>> Weavers are a completely different story. >>> >>> By leaf litter I did not mean just leaves, however they are used by most >>> Laughingthrushes for nesting for example (But as you said leafy >>> surroundings). Small pieces of leaves, stalks, shafts, cotton (We get lots >>> of silk cotton from silk cotton trees (deciduous) in this season here). >>> After all, birds are superbly resourceful and can work well with abundantly >>> available things. >>> >>> The need of better view, (for predators) of nest may not be certainly >>> bothering big birds like Golden Eagle, but for smaller birds it may be of >>> little greater importance especially when they wouldn't want to reveal >>> their nests. I've observed how hesitant they are to enter, if you're near >>> their nests. >>> >>> And in addition things I said earlier about food availability. Of >>> course, what I said was in a general manner & conjectural, for the >>> imprecise question, but a very good one. There obviously is more to nesting >>> behaviour than it meets the eye and only can be commented on with accurate >>> studies and observations. Although, I know nothing; I believe, it must be >>> one of the least studied aspects of Ornithology no matter how well >>> documented it must be but poorly reasoned. >>> >>> Thanks for your great inputs. I'd love to read more :) >>> >>> Best, >>> Saurabh >>> >>> On Thu, May 24, 2012 at 3:52 AM, Hans Peeters <[email protected]>wrote: >>> >>>> Dear Saurabh, >>>> >>>> I must confess that I'm not at all familiar with the nidification of a >>>> great many Indian birds; for example, I know nothing about the nests of >>>> fulvettas, shrike-babblers, and minlas. In the areas of the world that I >>>> know well, the vast majority of birds place their nests in well-hidden >>>> situations and begin nesting when the weather (and not the climate, which >>>> is a given) is optimal for raising young. The main factor, I believe, is >>>> the abundance of food for the offspring. Our common accipiter here in >>>> California, the Cooper's Hawk, builds its well-hidden nest in March and >>>> April and fledges its young in June, when there is a maximum number of >>>> inexperienced, newly fledged songbirds available for its own clumsy >>>> youngsters that are just learning to hunt. >>>> >>>> Birds that breed in extremely exposed situations, such as leafless >>>> trees, almost always seem to be large enough to defend eggs or young >>>> against any potential predator, and they seem to see no need to hide their >>>> nests. Almost always, these are large birds such as herons, storks, big >>>> raptors, etc. (in our last trip to India, in Feb/Mar, we noticed all the >>>> black kite nests going into perfectly bare trees, and even a crow nest here >>>> and there). At a minimum, there is at all times normally one adult at the >>>> nest once it holds eggs or small young; once the young are well grown, both >>>> the adults will leave the nest alone and forage. The only smallish, >>>> relatively helpless birds I know that build in exposed situations are some >>>> of the caprimulgids (for example, the potoos of South America), which rely >>>> on the camouflage of the adult and the young, and the fairy tern of Pacific >>>> islands which lays its egg directly onto a limb, benefiting from the >>>> absence of predators. >>>> >>>> Other than that, I cannot think of any small birds that cleverly >>>> disguise their nests in bare trees, and I would be really interested in >>>> learning of species that do so. I suppose you might mention the spotted >>>> creeper, whose nest, however, sort of melts with the bark of the tree. I >>>> have seen the nest of drongos and the nests of some other passerines which >>>> seem to be fairly obvious hanging from or saddling a limb, but the ones >>>> I've seen have been in leafy trees, not in bare ones. Weavers build very >>>> conspicuous nests, sometimes in bare trees, but the nests themselves appear >>>> to be virtually impenetrable except to certain snakes. Plus, they nest >>>> colonially -- there's safety in numbers. Lichen-covered hummingbird nests, >>>> which for all the world look like a knot on the limb on which they're >>>> built, nevertheless are usually placed in leafy locations. >>>> >>>> Note that the nests of the larger birds I mention earlier are robust >>>> affairs, made of sticks, sometimes even very large ones. Leaf litter is >>>> rare building material, and when used, it typically will be by a bird >>>> nesting in leafy surroundings. >>>> >>>> I don't believe that birds need a better view of their nest site nor >>>> any help in spotting predators. Golden eagles in California, for example, >>>> whose nests may be either exposed or well hidden in the crowns of oaks, >>>> know precisely where their nest is, fear no predators, and often approach >>>> the nest flying under the canopy, where they cannot see their objective. >>>> >>>> All this from Rajesh's innocent but perfectly good question why birds >>>> nest in bare trees. >>>> >>>> Best regards, >>>> Hans >>>> >>>> >>>> On Tue, May 22, 2012 at 8:07 AM, Saurabh Sawant < >>>> [email protected]> wrote: >>>> >>>>> Quoting my reply to this question, from facebook, as I'd be happy to >>>>> learn more on this: >>>>> >>>>> "Nesting activity is influenced by a number of factors. And >>>>> considering the scope of this question; which only appears to be narrow at >>>>> first can be really vast, it can be addressed better if it is specified >>>>> for >>>>> particular group of birds. Because, different species have different >>>>> preferences and habits though the habitat could be the same but for >>>>> different reasons & microhabitats. >>>>> Some of the major, apparent factors that influence the nest site >>>>> choice could be Climate, Predators, Availability of Food & perhaps, >>>>> Availability of nesting material. There could be numerous smaller and >>>>> subtle factors which play a big role in choosing nesting site for birds >>>>> create a highly localized environment to their preferences. >>>>> Firstly it avoids a lot of efforts and competition for not so abundant >>>>> nesting sites. So it's better to adapt than to compete. Most of all these >>>>> birds which make their nests in the open on branches of deciduous trees >>>>> are >>>>> extremely well camouflaged and cryptic. And believe me, are extremely hard >>>>> to locate. So, whether in the open or not, they are well hidden. They must >>>>> be helping the birds probably to have a better view of their nest site and >>>>> predators lurking around. It may be associated with direct sunlight in the >>>>> morning, vegetation cover above or brood temperature. Other animals may >>>>> not >>>>> be finding such sites suitable for shelter which would avoid attracting >>>>> predators. The twigs, branches, leaf litter from deciduous trees must be a >>>>> good source of nesting material and also superb habitat / shelter for many >>>>> animals including most of bird's prey base. Deciduous trees will have new >>>>> leafbuds, young leaves, flowers, fruits as soon as the season passes or >>>>> comes near its end. Which may be a great food source for birds or other >>>>> animals which are part of bird's diet. etc.. These are a few in general >>>>> and >>>>> there could be many such factors. >>>>> Questions such as these can be addressed effectively if pertained to >>>>> specific group of birds or species. But of course, only after a lot of >>>>> observation. :)" >>>>> >>>>> Regards, >>>>> Saurabh >>>>> >>>>> On Mon, May 21, 2012 at 3:02 PM, Rajesh Sachdev >>>>> <[email protected]>wrote: >>>>> >>>>>> It is observed that the nesting birds , camoufledgly build or >>>>>> regenerate their nest every season. It is also understood that they try >>>>>> every step hard to hide their nest with local vegetation or foliage. >>>>>> Than, >>>>>> why many birds build their nest on deciduous trees, which are >>>>>> bare/leafless >>>>>> in the season of summer or before spring. And that is the time when most >>>>>> of >>>>>> resident birds are in breeding plumage and busy with their nesting >>>>>> activity! >>>>>> >>>>>> -- >>>>>> Regards >>>>>> Rajesh Sachdev >>>>>> http://project-matheran.webs.com >>>>>> https://www.facebook.com/leopardguy >>>>>> >>>>>> >>>>>> >>>>>> -- >>>>>> You received this message because you are subscribed to the Google >>>>>> Groups "delhibirdpix" group. >>>>>> To post to this group, send email to [email protected]. >>>>>> To unsubscribe from this group, send email to >>>>>> [email protected]. >>>>>> For more options, visit this group at >>>>>> http://groups.google.com/group/delhibirdpix?hl=en. >>>>>> >>>>> >>>>> >>>>> >>>>> -- >>>>> Regards, >>>>> Saurabh Sawant >>>>> _ >>>>> "The foot feels the foot when it feels the ground." >>>>> >>>>> http://www.facebook.com/saurabh.sawant >>>>> >>>>> http://www.flickr.com/photos/40451253@N04/ >>>>> >>>>> -- >>>>> You received this message because you are subscribed to the Google >>>>> Groups "delhibirdpix" group. >>>>> To post to this group, send email to [email protected]. >>>>> To unsubscribe from this group, send email to >>>>> [email protected]. >>>>> For more options, visit this group at >>>>> http://groups.google.com/group/delhibirdpix?hl=en. >>>>> >>>> >>>> >>>> >>>> -- >>>> Hans Peeters >>>> 1050 Kilkare Road >>>> Sunol, CA 94586 >>>> USA >>>> 925-862-2102 >>>> http://peeters.homestead.com >>>> http://www.ucpress.edu/books/pages/10558.php >>>> http://www.ucpress.edu/books/pages/9944.php >>>> >>>> >>> >>> >>> -- >>> Regards, >>> Saurabh Sawant >>> _ >>> "The foot feels the foot when it feels the ground." >>> >>> http://www.facebook.com/saurabh.sawant >>> >>> http://www.flickr.com/photos/40451253@N04/ >>> >> >> >> >> -- >> Hans Peeters >> 1050 Kilkare Road >> Sunol, CA 94586 >> USA >> 925-862-2102 >> http://peeters.homestead.com >> http://www.ucpress.edu/books/pages/10558.php >> http://www.ucpress.edu/books/pages/9944.php >> >> > > > -- > Regards, > Saurabh Sawant > _ > "The foot feels the foot when it feels the ground." > > http://www.facebook.com/saurabh.sawant > > http://www.flickr.com/photos/40451253@N04/ > -- sushant
