Spider explosion

Mangroves covered in spiderweb
Mangroves covered in spiderweb

I stopped off at one of my inner-city parks three weeks ago and saw the biggest spider colony I’ve seen for quite some time. I was more than slightly boggled by it. Skeins and swathes of web stretched from one mangrove tree to the next along at least 20 metres of creek bank, overhanging the water and within about 1.5 m of water level. (It’s the bank on the far side of Ross Creek from these cormorants.)

Looking into the web ...
Looking into the web …

When I looked more closely I saw long skinny orange-brown spiders (1), lots of smaller chubbier charcoal-white patterned spiders (2), and a few very small ones (3); also lots of egg sacs woven onto twigs.

I reckoned that (3) were very young juveniles, that most or all of (2) were sub-adults and that (1) were adults, all of one species. “Which species?” is the obvious question. Not so obviously, why did all the adults I photographed happen to be males? Do sub-adult males change from type (2) colours to type (1) with their last moult, I wondered, while adult females remain type (2)?

Identifying the adults to genus level is easy, since the enormous jaws are very distinctive. They are in the genus Tetragnatha in the family Tetragnathidae. Both genus and family have the common names ‘Four-jawed Spiders’ (an exact translation of Tetragnatha) or ‘Long-jawed Spiders’. Beyond that, identification is less certain. They may be Tetragnatha nitens, T. rubiventris or another close relation (follow this link for photos of each species).

On a second vist two weeks later I saw many adult females with the reddish coloration, so any gender imbalance was only temporary. The webs were just as extensive and the egg-sacs even more numerous, although spider numbers seemed to be a little reduced.

I normally see adult spiders in this family as individuals (e.g. this collection), often well away from water and often with hardly any web, let alone a tent city like this. The expert I call on for things arachnological suggested that this could be a local ‘population explosion’, for whatever reason. He hadn’t heard of it with this genus but says it does happen with others, mentioning one of the St Andrews Cross species as an example.

What will happen here remains to be seen. I will call in again and report back … if I emerge alive. I’m just joking, of course – they are completely harmless, and the biggest risk to me is that I will fall in the creek while trying to take a better photo.

Tetragnathidae
Part of the web on my second visit

 

Big ball of fluff – baby Blue-faced Honeyeater

Wandering around the garden a couple of days ago, I spotted a big ball of fluff high in the paperbark tree. I could see that it was bird with a lot of white on it, and it was big enough to make me wonder briefly whether a Torres Strait Pigeon had over-stayed its wet-season visit. The telephoto lens, however, revealed that it was a very young Blue-Faced Honeyeater, Entomyzon cyanotis. It still had its fluffy baby-feathers on its white belly, and it was looking awkward and unsettled in spite of the company of an older bird, perhaps a parent.
It was too high in the foliage for a good photo that time but I saw it (or a sibling?) again yesterday, low in the poplar gum:

Blue-faced Honeyeater
“Blue-faced” Honeyeater? Not when they are this young

The species is named for the patch of skin on its cheeks, which is bright blue in adults. Younger birds have green cheeks but this one is the first to make me notice that the green changes gradually as they grow up, from this yellow-olive green which nearly matches their feathers, to the leaf green I see more often, and then to the blue.

Blue-faced Honeyeater
Feeling a bit exposed?

Mistletoebird and Flycatcher

Leaden Flycatcher in shrubbery
Leaden Flycatcher

We’re well into the Dry season now and, as I said when I introduced the Leaden Flycatcher two years ago, the bird population of our garden builds up as the surrounding countryside dries out. We’re going to see even more this year, actually, since Townsville has just gone on to Level 3 water restrictions, meaning that parks and most gardens will also dry out while our bore water will keep our garden green.

Photographing the smallest birds is a special exercise in patience and luck. Many of them like to forage in dense shrubbery where they can move freely but bigger birds can’t, and where they are safer from attack. They are also safer from the paparazzi, since they rarely offer a clear shot (the oddly blurred background of the photo above is out-of-focus foliage) and they are often in shadow or dappled light.

Which species am I talking about? Particularly Sunbirds (11 cm), these Flycatchers (15 cm) and White-throated and Brown Honeyeaters (both about 14 cm). (By way of comparison, the Cairns Birdwing butterfly has a wingspan of 12 – 15 cm.) Spice Finches (11 cm) are just as small but at least they tend to feed in the open.

The Mistletoebird, Dicaeum hirundinaceum, is another member of the list. At 10 cm and 9 gm (the weight of two teaspoons of sugar) it is one of our smallest, and it flits about erratically, high in the tree canopy.

Mistletoebird
Mistletoebird high in our paperbark tree

As Bird in Backyards notes, Mistletoebirds are found Australia-wide and feed on berries of the plants they are named for, having an important role in distributing the seeds. Mine is a male; the females are basically grey, darker above than below. The species is our only member of Dicaeidae, the Flowerpecker family. Its nearest Australian relatives seem to be Sunbirds.

Bee-eater lives up to its name

rainbow bee-eater
Rainbow Bee-eater

As I’ve said before, Rainbow Bee-eaters (Merops ornatus) take small flying insects on the wing, swooping from their perch and returning to juggle their prey for consumption. I saw this bird fly from our neighbour’s power line and was just able to get a shot through foliage a minute later. Its prey is, appropriately, a European honey-bee.