About scientific ringing

04 August 2022

NOVA FALCONS, ENVIRONMENTAL COMPANY OF EVISSA AND FORMENTERA; SPECIALIZED IN SCIENTIFIC RINGING, STUDY, MONITORING AND CONTROL OF wilD live.

Brief introduction

To introduce us to scientific ringing, we have to go back to 1899, and make a small jump from Eivissa to Denmark. In Denmark, Hans Christian Cornelius Mortensen decided to put a numbered ring with a return address on a group of starlings and release them again. In essence, this is the basics of scientific ringing: place a numbered, sender band on a leg, note the record, and release the bird to see what happens. Obviously, things have evolved a lot since then, and as we will try to explain in a brief and pleasant way, nowadays scientific ringing, like any other scientific discipline, requires continuous training, vocational dedication and specialization, which cannot be achieved without years of work and effort.

Male european stonechat (Saxicola rubicola), one of the most characteristic birds of the Pitiusan landscape.

The main purpose of scientific bird rings is to help us study and learn more about the different species in our environment. Through the placement of an official band, with a unique numbering, and that can only be placed with prior authorization and with a specific methodology, the bird that is banded is unequivocally identified. Once banded, a series of biometric data is collected, such as the measurements of different parts of its body (feathers, wings, tarsi, beak...), age (or an approximation as far as possible by means of a series of homogenized codes for all banders), weight, fat levels, musculature, health problems, etc. Thanks to this, we not only obtain data on age, sex, morphological characteristics, etc., but we can also know the exact points through which a bird passes during its migration, and which can lead it to cross countries from north to south (and vice versa); in some cases, in the case of birds that barely weigh 10 grams. Is there anyone who does not find it surprising that a mosquito of just 7-9 grams in weight is able to cross the Mediterranean Sea without even looking back?

A specimen of the bonelli's warbler (Phylloscopus bonelli), a bird that breeds in Europe, and migrates during the winter months to sub-Saharan Africa, that's nothing!

Female (left) and male (right) of woodchat shrike (Balearic) (Lanius senator badius); we can determine the sex by the color and intensity of the white, black and head. The age, second year female (EURING code 5) and adult male (EURING code 6), is determined by the presence in the female of juvenile feathers (not yet molted), and in the male a complete molt as an adult. The subspecies is determined by the difference in coloration of the primary feathers with respect to the nominal species. The subspecies Badius, is an endemism of the Balearic Islands, and that could well go unnoticed as a subspecies itself, without the previous work of ornithologists and scientific ringers.

Female black-capped warbler, showing incubatrix plate, EURING code 2: "Obvious vascularization. Some wrinkles (thick) a little fat under the skin. Pale pink color."

The code system used in Europe is the EURING code, from the supranational entity European Union For Bird Ringing. EURING was born with the purpose of homogenizing data collection and other aspects related to scientific ringing, since birds move throughout Europe (and outside Europe, obviously), without understanding borders or working methodologies. Therefore, EURING is a tool for all banders in Europe to implement banding in a more or less coordinated way, and under the same methodology.

Another aspect to take into account in the process of scientific banding is the active search for all anomalies or differences that may exist between individuals, both to avoid misidentifications between species that may be very similar, and precisely, to find new features that give rise to complementary studies (such as genetic studies), which in turn allow differentiating new species. Species that until then were included within others of similar appearance and characteristics. The taxonomic world is in constant evolution, and birds are no exception.

As far as the rings themselves are concerned, there are different models, materials, colors and sizes, which are applied according to the species and habitat, and even sex, when there is a great sexual dimorphism within the species. This is something that happens, for example, with large diurnal raptors, where females are usually significantly larger, and consequently, have wider tarsi. Thus, we can find aluminum, steel or even PVC rings. In the case of the latter, they are usually always accompanied by a metal ring (i.e. sometimes more than one ring is used). The main purpose of these PVC rings is that they have a code based on colors, numbers and letters, much simpler and larger, which in practice, allows the reading of the ring, without the need to recapture the bird.

Female specimen of blackcap, with an aluminum ring.

Placement of a steel-ring model on a barn owl (Tyto alba).

As far as the rings themselves are concerned, there are different models, materials, colors and sizes, which are applied according to the species and habitat; or even sex, when there is a great sexual dimorphism within the species. This is something that happens, for example, with large diurnal raptors, where females are usually significantly larger, and consequently, have wider tarsi. Thus, we can find aluminum, steel or even PVC rings. In the case of the latter, they are usually always accompanied by a metal ring (i.e. sometimes more than one ring is used). The main purpose of these PVC rings is that they have a code based on colors, numbers and letters, much simpler and larger, which in practice, allows the reading of that ring, without the need to recapture the bird. Of course, apart from rings, there are also other types of tags, such as wing tags or collars.

In addition, the appearance of new materials, designs and technologies makes it possible to implement more and more different types of GPS marking, both real-time reading and reading through GPS recovery. Scientific banding, like any other scientific discipline, is subject to a slow but constant evolution, which translates into new equipment, tools and constant improvement of the quality and efficiency of the data collected.

Capture methods

There are several methods of capture, namely, nets, snares, net traps, trap cages.... all with different functions and materials, but with one thing in common: they must be able to capture the bird in perfect physical condition.

Extraction of a small green serin (Serinus serinus) from a Japanese net, as can be seen, it is removed in perfect condition. On the other hand, the particularity of this method of capture is the "invisibility" of the nets, as long as they are placed correctly!

On the other hand, whatever method of capture is used, it must always be authorized by the competent authority, and must always be used with constant supervision, both to avoid deaths due to exposure to environmental conditions, and to avoid self-injury when trying to free the bird, or even predation by potential predators present in the area (the latter can happen all too easily, for example, in areas where there are feral cats).

Training process

There are two ways to carry out scientific ringing, and both must be authorized by the public administration. One is to request a specific authorization, supported by a project and personal trajectory that justifies both the need for banding and the capacity to implement it; and the other is to undergo the official training necessary to be qualified as a bander.

In order to obtain the bander's license, there are slight differences between autonomous communities, but roughly speaking, it will be a process of about 2 years, where you have to access first to the auxiliary license, and then to the expert one. In order to take both exams, you must first meet a certain number of banded species and field days, endorsed by expert banders. That is to say, a bander in training can never band alone, and will always be accompanied by an expert bander in each of the field days he/she carries out.

The tests are carried out by the coordinating entity of the scientific ringing of the autonomous community in question, in the case of the Balearic Islands, is the Grup Ornitologic Balear (GOB).

This year, thanks to a previous training work that has been done during last spring and winter, we have been authorized to band and collect the biometric data of some of the species that we capture in the SCF of Ibiza Airport, and then are translocated to other areas of the island where they are not problematic, being one of the main species, the common kestrel (Falco tinnunculus).

Comparison of tail coloration in two juvenile kestrels, left probable male, right probable female.

This work of banding and data collection is voluntary. And it is, both for the company that develops it without a specific commercial purpose, and partly for the staff, since there is an involvement on their part, which goes beyond the strictly labor. And this is so, for purely ornithological and formative interest. Perhaps this last aspect is the most interesting, because the truth is that it is really difficult to access this type of training in Ibiza and Formentera. This, in turn, has a direct impact on the lack of banders and ornithological projects in the Pitiusas, despite the amount of data and information that could be collected, both at migration time, as in stations of constant effort or studies of specific species.

For this reason, it is undoubtedly necessary to thank the totally disinterested collaboration of the ornithologist Oscar García, from the Societat Ornitológica de Menorca (SOM), who has made these training sessions on scientific banding possible, sharing with us his years of experience.

A specimen of Barn Owl Tyto alba), and part of Oscar García's arm holding it for the photo.

Photographs: unless otherwise specified, Borja Pérez; and unless otherwise indicated, all photos have been taken in Eivissa or Formentera.

Text: own elaboration.