One of the things I find most rewarding about maintaining this blog is the contact it gives up with people outside the SEANET community. When members of the public see anything unusual in the seabird world, they tend to head straight to the internet and google what they’ve seen. Searching “tagged bird” or “tagged gull,” or “dead bird on beach” for instance, will bring up our blog among the first few results.
Last week, I received an email from a woman in Massachusetts alerting me to an ongoing discussion among birders and bird photographers about the appropriate treatment of rare and unusual birds. How much disturbance is acceptable, for instance, in pursuit of the perfect shot, or ideal view? In the course of this discussion, humane concerns for the birds came up often, and someone brought up banding and tagging birds under that umbrella.
I visited one of the photo fora where the discussions were taking place, and was surprised to find a picture of a SEANET tagged bird, bearing its orange cable ties and aluminum tag. The caption suggested that the bird had died from the tag’s presence, and that it was cruel practice. Of course, we at SEANET tag only dead birds, so cruelty and humane treatment are not relevant to our study, but public perception certainly is, so I elected to take the opportunity to educate the public about some of the ongoing bird tagging studies they may encounter in their travels, particularly here in New England.
A SEANET tagged bird: orange cable ties and an aluminum tag are placed post-mortem. (photo: W. Stanton)
The purpose of marking, banding or tagging any bird is to study it. By recording all sightings of a given bird after it is captured and marked, scientists can get at least a rough picture of where it travels, rests, breeds, and so on. The larger and more conspicuous the marking, the more likely the bird is to be noticed, recorded and reported. The spectrum runs from the metal, federal bands placed on the legs of songbirds caught in mist nets, to large fluorescent wing tags with obvious alphanumeric codes. Even the largest of the metal federal bands are impossible to read with the naked eye on a live bird with any power to get away, and so these are generally only reported when a bird is recaptured and the band can be read in the hand, or by birders with spotting scopes and a lot pf patience, or when the bird is found dead. This means that very little can be gleaned about a bird’s travels when only a federal band is placed.
Field readable bands boost resightings well above plain metal bands. (photo: Jon Worthen)
To help boost sightings, many projects (including our own Julie Ellis’ study on gulls breeding on Appledore Island, Maine) utilize what are known as “field readable bands.” These are usually brightly colored PVC or metal bands with a short, clear alphanumeric code. These bands can be read easily with binoculars, or if a bird (a gull, for instance) approaches closely in order to steal your sandwich. While using the field readable bands does substantially boost resightings, it’s still mainly people with binoculars or at least a nice camera who record and report these bands.
A ring-billed gull tagged for the Mass. DCR study.
A few steps beyond field readable bands are the gaudy, fluorescent wing tags used, for instance, by the Massachusetts’ Department of Conservation and Recreation water quality study. These large tags result in amazing resight rates. Around 70% of birds tagged in this way are seen by a member of the public at least once subsequent to release. This is several times the resighting rate attained in many studies using only field readable leg bands. I wrote to Dan Clark, who is one of the principal investigators on the DCR study, and asked him about the tagging methods, and how they respond to people worried about the impacts the tags have on the birds. He responded,
“We have tagged over 1500 gulls. These gulls have flown hundreds of miles (ranging from Florida to Newfoundland), strongly suggesting that the tags don’t interfere with flight, and individuals have survived multiple years with the tags. These tags are not permanent – they eventually come off. The gulls we’ve recaptured without their tags show a small area of scar tissue where the tag was, but no damage to the wing or ability to fly. It is important to recognize that any wildlife study that handles and marks individuals always has the potential to influence the behavior or life expectancy of the animal. Researchers must always weigh the importance of the data being collected against the potential to impact the study animal. We were careful in our preparation and execution of tagging. We sprayed each tag with antiseptic before deployment to discourage bacteria. Of all the tagged birds we released, less than 10 were found dead or injured. In only 2-3 cases was the wing-tag suspected of contributing to their condition. We felt our study objectives (gulls and drinking water quality for 2.2 million people in metro Boston) justified the capture and marking of individual gulls. The data we received has contributed to our knowledge of inland gull ecology and informed our management decisions as we strive to maintain high water quality standards.”
To give you a sense of the anatomy of the wing where the tags are placed, take a look at the diagram below.
The black triangle roughly outlines an area called the patagium. This is a membranous region of skin with an elastic tendon at the leading edge. There are no bones in this area, nor are there any blood vessels. This makes it a very good candidate for placing a wing tag. The DCR tags were affixed by making a small puncture in that patagium and securing a rivet through the hole. The most apt parallel in humans would be an ear piercing. As Dan pointed out, complications from these tags are exceedingly rare.
While Dan is finished with the wing tagging aspect of his study, these are long-lived birds, and you are likely to see them out and about for several years. Hopefully you will spot a few and report them, and please, help us spread the word to concerned members of the public–these are well-supervised, well thought out studies carried out by dedicated and conscientious wildlife scientists. We welcome your thoughts, comments, and questions, via email or via comments here on the blog.
Happy tagged bird sighting!