In May 2008, Adrian Lim a.k.a. wmw998 documented a pair of juvenile Asian Glossy Starlings (Aplonis panayensis) copulating, or so it seems (below).

“Are they actually copulating or just experimenting as with most juveniles?” he wonders.

Birds learn from observing the adults, and this includes copulation. So obviously, the juveniles were imitating the adults when the older juvenile mounted the younger. The age difference can be seen in the eye colour.

There are actually reports of juvenile birds playing at copulation or practicing at it. It is doubtful whether at that age these birds can differentiate the sexes, let alone being sexually matured.

The colour of the eye comes from the iris that surrounds the black pupil. In some species, eye colour changes as the bird ages. In others, the sexes differ in eye colour. In yet other birds, the eye colour of the juvenile is duller that that of the adult. In bulbuls, the eye colour varies with the species.

How eye colour affects social behaviour has not been extensively studied. But some ornithologists believe that this can reflect different social positions and, like plumage, colour may play a role in social interaction.

In Asian Glossy Starling, however, the juvenile has a different plumage from that of the adult. So the social status of adult and juvenile can be easily distinguished. However, among the juveniles, the eye colour of the younger juvenile is brownish, distinctly different from that of the older juvenile (above) and adult. Here again, there is obviously a distinction between young and old juveniles.

All images by Adrian Lim.

Referencs:
Clark, G. A. Jr. (2004). [‘Form and function: The external bird.’]. Pp. 3.1-3.70 in Podulka, S., Rohrbaugh, R.W. Jr & Bonney, R. (eds.) Handbook of bird biology. Ithaca, NY: The Cornell Lab of Ornithology.

This post is a cooperative effort between NaturePixels.org and BESG to bring the study of bird behaviour through photography to a wider audience.

Yvette Lim was at home one May 2008 morning when she heard a loud thud coming from her balcony window. There, on the floor, was a stunned female Laced Woodpecker (Picus vittatus). She sent in the image she took with a note:

“I consider it a real perk to have moved into a new home (well, not so new anymore!) where White-crested Laughingthrushs (Garrulax leucolophus), Tanimbar Corella (Cacatua goffini) and other (equally vocal or not) birds are a daily sight. We had one such visitor the other morning - the poor fellow smashed into our balcony glass door, and sat stunned and gawping for a good ten minutes before fleeing the scene.”

To find out the reasons why birds crash into buildings with glass panes, click HERE: 1, 2, 3 and 4.

NOTE: KC Tsang helped in the identification of the woodpecker.

Aydin Örstan from Maryland, US read the early post on “Where do birds go when they die?” and sent me a link to his series of posts on the same question, “Where do all the dead birds go?”

With Aydin’s permission, I am summarising his series of posts that you can view in full HERE: 1, 2 and 3.

A Gray Catbird (Dumetella carolinensis) was picked up on a sidewalk. From the condition of the dead bird, it was obvious that it had died probably not more than an hour or so earlier (left top). He put the body in a box and left the box in a secluded corner of his garden and ensured that the many “body snatchers” around did not get at it.

On day 2, there were flies around the rotting body - blow flies (Family: Calliphoridae) (left, second). They obviously detected the smell of the dead animal and arrived to deposit their eggs on the carcass. There were also plenty of ants crawling all over. There was a distinct smell indicating that decomposition had set in.

On day 3, there were more flies and more ants on and around the bird. There were many loose feathers, small ones, around and the tail feathers had fanned out, signs that the skin and the flesh had broken down (left, third).

On day 4, the smell was overpowering, indicating that decomposition was at its highest. Blow fly maggots were everywhere, on and around the body (left bottom). The carcass had disintegrated, with the skull partially visible (below left). The orange arrow shows the larger maggots and the yellow arrows the maggots at a younger stage.

On day 8, all the flesh and skin had been consumed and only the feathers and bones were left. There were no more maggots around, only a few ants (below right).

As Aydin concludes, “Dead things don’t go to Heaven or Hell. They rot, get eaten and turn into soil… Many organisms have evolved to obtain their nourishment solely from dead animals or plants. In nature, nothing goes to waste and nothing lasts forever.”

Check out today’s message by Aydin HERE on BESG’s website and how he gets “bored from looking at the seemingly endless species lists or just pictures of birds… that I regularly read. In contrast, almost all posts at the BESG blog have something to do with an interesting bird behavior and are accompanied with good, original pictures. I find them quite informative.”

The recent post on the Javan Myna (Acridotheres javanicus) chick that was predated by a cat brings to mind a common question many people ask: “Where do birds go when they die?” A related question I was recently asked was “Do birds die?” Such questions are understandable (or are they?), considering that with so many birds around, it is not common to come across dead birds.

Banding activities in our Sungei Buloh Wetland Reserves have shown that most of the sunbird species live at least five years. Many birds live much longer than this. But not all birds live as long, especially when they are victims of predation. Or when there is a food shortage and they starve.

I suppose when birds are about to die of sickness or old age, they do not move to some exposed areas. Usually they hide in the undergrowth or among the foliage of plants. And when they actually succumb to death, their bodies do not lie around as such for long.

I found a dead Yellow-vented Bulbul (Pycnonotus goiavier ) under some plants recently (left top). As an experiment, I left it on the ground and monitored its condition. Five days later (for some reason or other, the neighbour’s cat did not take it) most of the flesh was gone, leaving only feathers and bones (left middle). Another 12 days later, most of the bones had rotted and the feathers were fast disappearing (left bottom). So, under our hot and wet conditions, the carcase does not last long.

In the urban environment, you may come across the carcasses of dead birds in your garden. These are mostly victims of domestic cats (see 1, 2, 3, 4 and 5). These cats have been known to bring their trophies and place them at the feet of their owners. Or they may simply eat the dead birds outright.

Anyway, dead birds do not remain around for long on the ground. Cats and other predators eat them up, the fleshy parts, that is. Within a few hours, if not within a day, the feathers would be ripped off and the flesh eaten, leaving behind the entrails and head. Even these disappear in no time at all, including the feathers and most of the bones. This was seen when the Javan Myna chick I was tending was predated by a cat. I recovered the carcase from the cat and left it in the garden (above left). By the next morning, nothing much was left (above right). Probably another cat ate it up.

These are the reasons why most people do not encounter dead birds in their daily lives. But this does not mean that birds do not die!

We have been looking at birds for more than two decades now. We have been paying attention to bird identification, fascinated by the plumage, as seen in the Black-naped Oriole (Oriolus chinensis) on the left. Currently there are many birdwatchers who are good at bird recognition. The Bird Group of the Nature Society (Singapore) has done an excellent job in this respect. This was done through courses, field trips, bird races, annual bird census, etc., all put in place in 1984 by Clive Briffett and his team.

The formation of the Bird Ecology Study Group in 2005 injected a little science to the mainly recreational activities of birdwatching. BESG, as this group has become known, introduced the study of bird behaviour.

While birdwatchers were previously mainly looking at birds, enjoying the diversity of bird life and compiling lists of species from different habitats, they have now been encouraged to observe birds. Observations on what food birds take, how they catch their food, their nesting habits, breeding ecology, interspecific interactions, etc. were collected and published in this blog (right).

Making such observations easily available to all was deemed crucial in encouraging birdwatchers to participate in data collection. In this respect we have been successful as evidenced by the ever increasing visitor number to our blog.

Although bird photographers were mainly sending in their photographic evidence initially, we now have traditional binocular-toting birdwatchers making behavioural observations in between listing species.

Three years into encouraging behaviour-watch, we have succeeded in making birdwatchers aware of the necessity of not just looking at birds, but also watching them. We are not stopping here but moving on. We hope to encourage birdwatchers to also listen to birds, not just looking and watching.

Birds make a series of calls and sing wide-ranging songs. Through the work of Sutari Supari, we have recordings of bird sounds. This is an excellent basic compilation. We need to improve on this, to record the entire repertoire of calls and songs of each species. Many species have more than one call and/or song. Only recently, Gloria Seow mentioned to me that she has noted that the Black-naped Oriole has a repertoire of at least seven songs.

We also need to slowly find out exactly what each call and song means. Are they made to defend territory, to attract mates, to warn others of predators?

We invite birders when out in the field to listen to birds, make notes and publish them to share these observations so that we can, together, build on our scarce knowledge of bird vocalisation.