Ascension Frigatebird soaring over Ascension Island.

Unlocking the Secrets of the Ascension Frigatebird: A Quest for Identity

Beau Callahan in Science & Nature August 2025 • 4 min read.

"How a 250-year-old seabird naming mystery was solved through a new type designation, ensuring clarity for future research."

In the meticulous world of taxonomy, assigning names to species is a cornerstone of biological understanding. A clear, universally accepted naming system allows scientists to communicate effectively and build upon existing knowledge. However, the path to establishing these names isn't always straightforward. This is particularly true when dealing with species named centuries ago, where original specimens may be lost and historical descriptions are vague.

The challenges of historical taxonomy are exemplified by the story of the Ascension Frigatebird (Fregata aquila), a large seabird found exclusively on Boatswain Bird Islet near Ascension Island in the South Atlantic Ocean. First described by Linnaeus in 1758, the original description lacked the precision needed to definitively link the name to the species as we know it today. This ambiguity threatened taxonomic stability, potentially causing confusion and hindering research efforts.

To resolve this issue, a team of ornithologists embarked on a quest to solidify the identity of the Ascension Frigatebird. Following the established protocols of zoological nomenclature, they carefully examined historical records, assessed previous descriptions, and ultimately designated a neotype – a new reference specimen that officially defines the species. This process ensures that the name Fregata aquila remains firmly anchored to the unique seabird of Ascension Island, providing a stable foundation for future research and conservation efforts.

The Case of the Missing Type Specimen: Why a Neotype Was Necessary

Ascension Frigatebird soaring over Ascension Island.

The initial description of the Ascension Frigatebird, penned by Linnaeus under the name Pelecanus aquilus, was based on existing texts and illustrations rather than a specific, designated specimen. Linnaeus referenced earlier works, including accounts from naturalists and artists who had encountered similar birds. While these references provided valuable clues, they lacked the precision required to definitively identify the species.

One key issue was the description's reliance on observations from a voyage to China by Pehr Osbeck, a student of Linnaeus. Osbeck described a frigatebird from Ascension Island with white on its head, breast, belly, and neck – a pattern resembling a juvenile Ascension Frigatebird. However, there was no guarantee that this description perfectly matched the modern understanding of the species. Moreover, the original specimen collected by Osbeck was likely lost, leaving taxonomists with no physical reference point.

To address these uncertainties, the ornithologists meticulously reviewed the historical context and considered the following:

Vague Descriptions: Early descriptions were often broad and could potentially apply to other frigatebird species.
Lost Specimens: The original specimens used to create these descriptions were no longer available for examination.
Taxonomic Instability: Without a clear type specimen, the name Fregata aquila could be subject to interpretation, leading to taxonomic confusion.

Given these challenges, the researchers concluded that designating a neotype was the most effective way to stabilize the taxonomy of the Ascension Frigatebird. A neotype would serve as a definitive reference point, ensuring that the name Fregata aquila is consistently applied to the correct species.

A New Chapter for the Ascension Frigatebird

By carefully designating a neotype for the Ascension Frigatebird, ornithologists have ensured the stability of this species's taxonomic identity. This meticulous work provides a solid foundation for future research, conservation efforts, and our understanding of this unique seabird. The story of the Ascension Frigatebird serves as a reminder of the importance of precise naming conventions and the ongoing efforts to unravel the complexities of the natural world.

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This article is based on research published under:

DOI-LINK: 10.1590/s1984-4689zool-20160111, Alternate LINK

Title: A Neotype Designation For The Ascension Frigatebird Fregata Aquila (Aves: Fregatidae)

Subject: Animal Science and Zoology

Journal: Zoologia (Curitiba)

Publisher: FapUNIFESP (SciELO)

Authors: Caio J. Carlos, Jean-François Voisin, Hein Van Grouw, Ignacio B. Moreno

Published: 2016-01-01

Everything You Need To Know

What is the significance of the neotype designation for the Ascension Frigatebird, and why was it necessary?

The designation of a neotype for the Ascension Frigatebird (Fregata aquila) was crucial to resolve taxonomic ambiguity and ensure the species's identity. Because the original specimen described by Linnaeus was unavailable and the initial descriptions were vague, the neotype served as a definitive reference point. This prevents future confusion in scientific communication and research by providing a concrete specimen to which the name Fregata aquila is unequivocally linked.

What challenges did taxonomists face when identifying the Ascension Frigatebird, and how did historical context play a role?

Taxonomists faced several challenges, including vague early descriptions of the Ascension Frigatebird, the loss of the original specimen and reliance on historical accounts. The initial description by Linnaeus, based on existing texts and illustrations, lacked the specificity required for precise identification. Historical context, such as observations from a voyage to China by Pehr Osbeck describing a frigatebird from Ascension Island, was considered, but the lack of a physical specimen created uncertainty. These challenges highlighted the need for a neotype.

Who first described the Ascension Frigatebird, and what name was initially given to the bird?

The Ascension Frigatebird (Fregata aquila) was initially described by Linnaeus in 1758. He placed the bird within the genus Pelecanus, naming it Pelecanus aquilus. This initial classification was based on existing texts and illustrations, lacking a specific, designated specimen, which eventually led to the need for a neotype.

How does establishing a clear taxonomic identity for a species like the Ascension Frigatebird impact research and conservation efforts?

Establishing a clear taxonomic identity for the Ascension Frigatebird (Fregata aquila) is fundamental for both research and conservation. A stable taxonomic foundation ensures that researchers across the globe can accurately identify and study the same species. It also allows for effective communication about the species's distribution, behavior, and genetic makeup, aiding in conservation planning. Without clarity, conservation efforts might inadvertently target the wrong species, hindering effective protection strategies.

Can you explain the process of designating a neotype, and why it's an important procedure in zoological nomenclature?

The designation of a neotype is a meticulous process in zoological nomenclature, essential when the original type specimen is missing or insufficient. Ornithologists meticulously reviewed historical records, previous descriptions and consider other species. Then, they select a new specimen, which then serves as the definitive reference for the species. This process ensures taxonomic stability, preventing confusion and misidentification, and providing a consistent basis for future research and conservation of species like the Ascension Frigatebird (Fregata aquila).