wind-up bird(s)

Introducing a new species, the wind-up birds.
The wind-up birds are a flock of mechanical woodpeckers, having found their first home in a forest in Lillehammer, Norway as part of the UT-21 project.

How will nature treat them, with hostillity or acceptance? How will the wind-up birds adapt to heat/cold wet/dry conditions? Will small insects creep inside the circuitry creating possible short circuits, beetles eat the wood, squirrels use the wood slit as nut storage (or the roof as a slide?), birds use it as a shelter, etc.? Will they be treated as foreign objects or accepted into the local eco-system?
How do real woodpeckers react? Are they threatened, attracted, or not bothered? Will they use the roof as a pecking drum?
Initial tests indicate an attraction: it took 15 minutes for a real woodpecker to join a wind-up bird on the same tree.

Adding a layer to the perceived reality:
The sound of the wind-up birds easily fool humans. The initial reaction is surprise, and then bewilderment, as there seems to be a whole flock of birds communicating. Then the curiosity of trying to track them down, to localize the sound, becoming more aware of the surroundings, sharpening the senses.
This was the initial motivation for me, the movement of sound in a space, and the effort involved in trying to localize the source of the sounds which lead to a stimulation of our perceptive apparatus.
By introducing an element or layer which somehow relates to the environment, but still is a bit off (It is very unlikely to hear a flock of woodpeckers drumming at the same time, and it is usually restricted to the mating season in the spring), you perceive the reality differently. This could be called an animalistic alertness, one of the three listening modes described by Barthes  (Listening).
This project is related to my soundpockets project, and as with that work I feel it is somehow more interesting when people happen upon it by chance, instead of looking for a piece of art in the forest.

The development of the wind-up birds have gone through a lot of phases:
It was important for me that the sound produced was not playback of a recorded sound, but mechanically produced, so I looked at many different ways of creating resonance boxes and ended up with a construction resembling a wood block: a piece of wood with a slit. I ended up using a simple push-magnet solenoid for the mechanical part.
The first prototype was an arduino board, the solenoid and the woodblock, trying to find the right pecking frequency for the solenoid, and testing different woodblock designs.
I decided to add a roof, to protect the wood and circuitry from heavy rain.

Since the wind-up birds are communicating, they needed to be in a wireless network. I decided early to use the xbee radios which are programmable, low-energy, high speed radio modems which can work in a mesh network.
A lot of effort was put into creating and deciphering xbee datapackets to be used in the arduino/processing environment.
Energy consumption was an important factor in the project, since the wind-up birds would be in a forest with no access to electricity and should be active for a month. One strategy was to use low-power components. It´s amazing the difference between two voltage regulators for instance when they have to be on for a month(the difference in consumption was the size of the battery I ended up using for the whole project).
I also decided to use a low power version of the arduino, basically just the microcontroller chip running at half speed (which meant using a AVR programmer to program the chips).
The other important factor in reducing energy consumption was to make use of the xbee and arduino´s capability to go to sleep when inactive. I decided the wind-up birds would be pecking about every 5 minutes, and inbetween they would sleep. Also at night they would be sleeping.
After having decided upon the components to be used, I designed a prototype circuit, which was later made into a proper circuit board making it easier to mass produce the birds.
It took a lot of trial and error to get the wind-up birds alive and pecking in the lab, but I had a pretty reliable setup when I placed them in the forest. The challenge in the forest was to find interesting locations within the range of the network, and to find interesting pecking patterns. I ended up making a system where the pecking pattern is different everytime, so it wouldn´t become a simple playback of movement, but a dynamic system.

More images of the wind-up birds

thanks to Tom Igoe, Jeff Mann, Kristian Skjold and Roar Sletteland for helping me realize this project.

Here is a link to the first technical post related to the project, which covers how to program and hook up a atmega168 as a minimal arduino standalone, using the internal oscillator running at 8mhz and 3.3 volts.