We arrived before first-light so as to set-up undetected. In my left hand I carried a small pet-kennel. Inside, a young black bird peered out ahead with curious, shining blue eyes. He utters a small, worried sound.
The tropical forest took on a different appearance in the electric blue beam of my headlamp. Our boots scuffed and scraped against sharp limestone projections as we made our way through tangled Guamia and Hibiscus. We ducked and crawled and braced ourselves, trying not to agitate the young birds. Seventy meters further and we arrived at our destination. We placed our feathered passengers in a large, waiting cage, and unravelled two mist nets. We were ready to begin. I squeezed myself into a blind garnished with large coconut palm fronds, and waited. My field partner was twenty meters away, in another blind, playing pre-recorded crow calls...
We are attempting to lure a pair of unbanded, adult Mariana Crows (Corvus kubaryi) into a pair of perpendicular mist-nets. If we are successful, they will make 10 radio-tagged birds that we can track using telemetry in order to monitor daily dispersal habits and behaviour. These corvids are found nowhere else in the world - only here, on the small island of Rota, in the Northern Mariana chain. The Mariana Crow at one time also inhabited the larger southern island of Guam, but their numbers plummeted upon the accidental arrival of Boiga irregularis, the Brown Tree Snake. Luckily, this voracious predator has not made an appearance here, but it may just be a matter of time.
Two hours later, and it is quiet. I press the small indiglo button on my watch: 7:02. Our “lure birds” - captive crows that have volunteered their time to help us out - are busy playing in their large cage in front of the nets. One examines a small stick while the other pulls dry leaves through the metal wire mesh. Then they sit close together on a perch to allopreen and make small noises to one another. Their presence is meant to attract the attention of our target birds.
In the distance the ocean can be heard rushing and frothing through the dimpled limestone shore, the wind lashing through Pandanus leaves. Fat raindrops fall from leaves of the Pisonia and Morinda trees above, blotting the coconut fronds of my blind. A few drongos and starlings dart about in the canopy making irritated shrieks and caws. The small fantails flash the orange undersides of their long tails. A dove lunges into the air in a whooping flutter of feathers.
All the while, hungry mosquitoes whine about my face.
Three hours later and the sun has climbed up into a blue sky. Scattered beams squeeze through the slats of palm fronds and thin, golden flecks of of light play upon the limestone karst beneath me. The air has become thick and heavy. A combination of the sun's warmth and the early morning rain create a blanket of humidity. The lure birds have found and eaten all of the geckos hidden in the leaf litter, and they make quiet begging noises in anticipation of their next meal. It is enough to force us from our cover, but our rogue pair is still at large.
It is time to go.
We place the young crows back in their carry-kennels, furl our nets, and begin our descent through the limestone forest. We have to give up on this pair for the time being and focus our attentions elsewhere. In the meantime, there is still plenty to do. This last remaining population of Mariana Crows needs all the help it can get if it stands any chance at a future...
