Thursday, 8 November 2012

Nests with Young

An important element of more serious birding is recording breeding activity.  Obviously if birds don't breed the species dies out pretty quickly and this it is important to understand what is going on with breeding activity.

The definition of 'breeding activity' is open to a range of interpretations with some people saying it is only the situations in which a nest is found with eggs or young that matters while others take a much wider view recording activities from 'breeding display' through to 'dependent young'.  In the COG  Garden Bird Survey most (57%) of the breeding records are of dependent young while only 10% of records report nest with eggs or young (most of those are of Nest with young).

Birds do not help with this type of endeavour often becoming secretive and quiet around the nests, especially when brooding.  However as with humans the young are much noisier than the adults, but rather than playing thrash-metal music at 300dB the birds simply yell for food.  Particularly in the case of bigger birds this makes the nests relatively easy to locate.  Here are a couple of examples.

White-winged Choughs make their mud-nest in eucalypts.  Even though the nests are quite large they get a bit crowded with the outcome of a communal breeding activity.

This nest is of Pied Currawongs and has been used for 3 of the last 4 years.  (For some reason they built a nest on the far side of the same tree last year.)   The chicks are now about 3 weeks old and very noisy when food is in in the offing.

Two weeks later (20 November) and the chicks are close to leaving the nest.
They actually hung on in the nest for nearly another week, the first one leaving on 25 November.  It left two colleagues behind:
I can't post about chicks without a photo of the very quiet Tawny Frogmouths.  I'm expecting them to leave the nest in about another week.  A more complete record of their activity is here.
Almost as soon as I had initially published this post I had an example of the difficulties of determining whether behaviour is a breeding display or not.  Three Striated Pardalotes turned up in a creeper outside our kitchen window.
They all seemed 'interested' in one another and there was considerable vocalisation.  Then two departed, leaving one alone on the wire.
If you should think I had initially stretched my discussion to allow me to post a couple of reasonable images of beautiful little birds you'd be spot on!  However subsequent events show that they were thinking about building a nest.

The next species is neither little nor beautiful.    It is a Noisy Friarbird and those with long memories will recall a post about them breeding here last year.   They are fairly faithful to their breeding sites so having heard a lot of Friarbird calls (the 'Noisy' element of their name is accurate) from the area of the last nest I have been paying attention to possible nest building activities.  No luck so far but I did get a nice picture.

No comments: