There Be Dragons!

Australian Water Dragons (Intellagama lasueurii) lounge and bask around pond edges at the University of Queensland, where I saw this handsome fellow. The colorful markings under his chin advertise his masculinity to the local lizard ladies… and to rival males too.

Researchers painted a model Water Dragon (actually a plastic iguana with a few glued-on additions) with either brown markings or red markings. (1) The toy was then introduced among resident Water Dragons to record their response to the intruder. When the toy had brown markings, the real Dragons attacked faster and more often.

Those fancy red and yellow stripes attract mates, but also deter rivals.

1. Baird, TA, TD Baird, and R Shine. 2013. Showing Red: Male Coloration Signals Sam-Sex Rivals in an Australian Water Dragon. Herpetologica 69(4) 436-444

The Sedum, the Finch, and the Corpse Flower

For over a year, my drawing has been sidelined by a misbehaving carpel tunnel. But I’m picking up a pen again for a fun little project (on a deadline set by a plant).

Lupin, the corpse flower at NC State, is growing another flower set to bloom about a week from now. The amazing greenhouse staff is preparing to host thousands of visitors who want to experience the olfactory disgust. I’m helping with outreach – stickers and coloring pages for younger visitors, and a map of the greenhouses to show off all the other non-corpse plants.

I’ve just finished this first small section of the map, the Sedum bed, and I am LOVING this. Since my hand needs a break, I thought I’d share the (very slow and laborious) process.

Sedum, or stonecrops, are succulants with thick, water-storing leaves. The ones in my yard are easily identified by adorable beak-bites taken out of them. Entire families of house finches settle onto the Sedum and clip mouthfuls of leaf, presumably for the water. I tried to research this behavior in the scientific literature to no avail. I found one lonely reference to an Oriole Finch in Tanzania eating Sedum leaves. That’s it. The behavior must be common since online message boards are full of complaints and advice on keeping the birds away from beloved Sedum in yards.

Seems like a great citizen-science opportunity to me!

Bee Bandits

Flowers need bees. A bee’s job is to move pollen from one bloom to another; plants pay for the bee’s service with sweet nectar. Cunningly, some bees have found a way to get a paycheck without the work.

Carpenter bees (Xylocopa sp.) exhibit a behavior called “nectar theft.” Rather than reaching the base of the flower through its opening (and getting a pollen dusting in the process), robber bees bite a hole in the base of the flower to slurp up nectar, bypassing the pollen-yielding anthers entirely.

We can’t necessarily blame them though, as it may be the plant’s own darn fault. Flowers with long tube-like bases are more likely to get robbed since the brawny carpenter bees can’t reach the nectar any other way (1). This relationship may even keep the flower tubes shorter over evolutionary time, since short flowers are more likely to be pollinated (and less likely to be robbed).

In order to deter break-ins, some flowers have evolved thicker flower walls, new toxins, or even special relationships with animal “special forces.” Some tropical flowers produce extra nectar in a special chamber for ants, who act like police in stopping the robber bees (2).

P.S. The bees I watched for this sketch were upstanding citizens – no thievery going on here!

P.S.S. It’s a girl! This bee’s got a black face. Males have a large patch of white on their faces. (http://www.uark.edu/ua/arthmuse/carpbee.html)

1. Navarro L and R Mendel. 2009. Relationship between floral tube length and nectar robbing in Duranta erecta L. (Verbenaceae). Biological Journal of the Linnean Society. 96 (2) 392-398.
2. Gerling D, HHW Velthuis, and A Hefetz. 1989. Bionomics of the Large Carpenter Bees of the Genus Xylocopa. Annual Review of Entomology. 34:163-190.

 

Going Nuts for Blue Jays

Watch out, squirrel. You’ve got competition this autumn.

Acorn gathering and burying is often considered a squirrel hobby. Turns out, Blue Jays (Cyanocitta cristata) are pretty good at it too. Okay, really good.

Blue Jays have a pouch in their throat they can use to hold acorns (up to 5!). When they reach a caching site, the birds will spit up the acorns and bury them one at a time under leaves or in the dirt.

One study showed that Blue Jays were responsible for relocating more than half the acorns in a forested plot. (1) That’s over 130,000 acorns! And yes, the birds usually remember where they’re hidden. They’ll often place the morsels near “beacons” like rocks or fences.

Another study suggested that the birds were the most likely culprit in the spread of oaks after the last Ice Age (2). Most trees with heavy seeds returned slowly to the barren lands left when the glaciers retreated. But the oaks came back quickly. Squirrels couldn’t do that, but Blue Jays could.

1. Darley-Hill S and Johnson WC. 1981. Acorn dispersal by the blue jay. Oecologia. 50(2) 231-232.
2. Carter JW and Adkisson CS. 1986. Airlifting the oaks. Natural History. 95(10) 40-48.

By the way, Lego(R) came out with a bird series this year – and it includes the blue jay. They should add a small Lego acorn to go along with it.