Groups were in the area of about 8-20 individuals and they have the fascinating behavior of laying all their eggs in one basket (or nest, if you want to avoid cliche presumptions!). This habit usually led to groups that primarily consisted of females and boy would they lay! Sometimes we'd have upwards of a dozen eggs in one nest and, by careful observation, we found that sometimes even females in the same group were still picky enough that they'd kick out an egg or two before laying their own!
Either way, though, the benefit of living in these territorial groups helped each and every individual because there's always a male or two lookout and birds that flock together can keep tabs on each other as well as the goings on around them.
Our job was to trap the birds using a variety of means, including enormous mist nets (which sometimes gave way to a good amount of by-catch as seen below by the mockingbird and the bananaquit!) But, when placement of the net was sucessful, we'd catch adults and band them according to an individual ID that we'd record down so we'd know what bird from whichever colony we pursued from one morning or afternoon to the next. Another, much more difficult means of capture was using a round wire trap with doors which were easy to pass in through but hard to get back out of (think crab traps). We'd use "bait" which were some anis that we raised ourselves to entice adults to go into the traps. Much less success here, but various trials and attempts, whether with nets or wire traps, most attempts were hit and miss a lot of the time.
Nevertheless, we did get some radio transmitters on various birds from different colonies so we had the ease of opening up the radio transmitter which helped us locate colonies at a much more rapid rate.
While the birds nested and fought amoung themselves (we even saw something of a "war" between adjacent colonies; prime real estate was at stake, you see.)
So, with colored bands and even painted beaks (using whiteout, which chipped off over time) we could get an idea of the various individuals and the hierarchy of a colony. And, when the nests didn't get raided by the horrible influx of rats to the island, we got to climb to precarious heights on extendible ladders to reach the nests and monitor the hatching and growth of the ani chicks and eventually, once large enough, get them banded too. By taking blood samples of the birds we caught, the research assistants had us bottling up tiny vials that would eventually give them the information that they could take back to do genetic work on to see what kind of success one female from the next was having in getting her genes passed along.
All in all, it was a fantastic fall in which we spent in the tropical dry thorn-scrub & grassland section of Puerto Rico, which really was a stunning place (and don't get me started about the magnificent cloud action I was constantly in awe of each and every day!). I hope you'll enjoy this little peek into one of the bird wonderlands that I was beyond fortunate to work within as a biological field technician, hands on with another fascinating species of the whole avian community which forever I hold in my heart as one of my favorite experiences (just another favorite among favorites)...