Pigeons Used in Research:
From barren single-housing to an enriched environment
by Anita Conte
College of Staten Island
Due to a 2002 amendment to the Animal Welfare Act, millions of birds used in experimentation each year in the United States are no longer defined as "animals," and are denied this federal oversight as a result. The conditions under which they are held are therefore open to interpretation. Researchers and institutions often afford them only the most basic welfare requirements. Most rely on tradition or manufacturer specifications when choosing caging for birds.
The pigeons in our research facility have a propensity to be long-lived, and unfortunately, they tend to be recycled from one experiment to another—eventually ending their careers as subjects in an Experimental Psychology Learning and Behavior class. Although we keep our pigeons clean, healthy and ready to serve the researchers, in reality we do patronize them and use them to serve our interests. However, I realized we could take better care of them.
Many of our birds had developed repetitive stereotypies after years of enforced inactivity and social deprivation in small, barren cages. These pathological behavior patterns are incessant and disturbing, but in my opinion, they also reflect a serious emotional imbalance in the individual animal. Other pigeons became listless—they ate and drank, but seemed disconnected. They appeared to have lost the edge their counterparts had in the wild.
Had our pigeons become "institutionalized?" Were they suffering such distress from boredom and inactivity that they were responding inappropriately to their surroundings, or directing that behavior onto themselves? This is a major concern because the release of corticosterone and other stress-sensitive hormones has effects that could confound data and the analysis of experimental results.
Thanks to an Animal Welfare Enhancement Award provided by the Animal Welfare Institute and the Johns Hopkins Center for Alternatives to Animal Testing, I was able to test for stress, as well as try to alleviate some of the distress of a group of white carneaux pigeons who had been in the facility for 10 or more years. I took fecal samples from them in their home cages to assess their stress status from the analysis of their corticosterone levels.
My coworkers and I built a flight pen considerably larger than the standard home cage, and I amassed quite a collection of bird toys. I bought two plastic shelters as escape points for any pigeons who felt threatened. The big day finally arrived, and the birds were transferred from their old single-bird cages into the new pen. Each chose a spot and stayed put; the pigeons were alert, but none wanted any contact with the others.
Eventually, they relaxed. We first saw locomotion, a considerable amount of wing stretching and even some running. Within a day I witnessed actual contact between birds. There was jostling, wing boxing and some half-hearted attempts to wrangle with one another. The pigeons glanced at the balls, bells and mirrors we provided, but completely ignored the standard "bird toys." I tried to be more creative, adding live wheatgrass, driftwood, foliage and ladders, but was again disappointed at the lackluster response.
I knew I had to observe pigeons outdoors to see exactly what they would be doing naturally. I saw that they were flying and walking around, scratching the dirt, jumping in puddles, and obviously not playing with manufactured bird toys! I removed all the enrichment devices and purchased a 25-lb. bag of large aquarium stones that I shaped into a mound. Rather than scattering the hay, I put whole bales in the cage. Wild pigeons are very interested in water, so I made them a "pigeon pool." I kept the shelters, however, because they were often used as secluded resting sites.
The birds were returned to the flight cage, and the bath was introduced. It was filled with warm water and pigeon salts. They approached it cautiously, yet all six pigeons finally obliged us by jumping in. There was barely enough room for all of them, but everyone got a turn. They splashed and played in the water for an entire hour. We had hit a home run!
Our pigeons were undoubtedly more interested in the natural items than the bird toys. I laced the stone mound with grain, and they foraged and picked through it for hours until the mound was flattened. The hay bales were good platforms to stand on, and amusing to pull apart. The shelters were excellent places for napping. The pigeons seemed to prize each other's company above all else—they spent much of their time sitting side by side.
Fecal samples will soon show if the working theory is correct: that the stress levels of our pigeons are indeed lower in the flight cage environment. These samples are in the process of being assayed, and we await the results with great expectations. In the meantime, however, we are proud to note that the pigeons' former stereotypic behaviors seem to have disappeared, likely due to their engagement in species-specific activities and the companionship of others.