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Sex identification of white storks (Ciconia ciconia) using biometric measurements of the skull, bill and tarsus

Witt, Karin (2020) BIOK01 20201
Degree Projects in Biology
Popular Abstract (Swedish)
Seeing double - Sexing of the white stork (Ciconia ciconia)

Imagine a world in which all humans looked the same and were indistinguishable between sexes. That is the confusing case of the monomorphic white stork (Ciconia ciconia). Since 1989 a breeding project has been in place to re-establish the white stork in Sweden. The project has been largely successful.

In conservation biology such as the Stork Project determining sex is essential for studying population dynamics and migrations patterns. Researchers are now facing a problem as these large birds look identical. At present, the sexing of storks is done through DNA analysis of blood or tissue samples. However, storks do vary in size and it seems males are, in general, larger... (More)
Seeing double - Sexing of the white stork (Ciconia ciconia)

Imagine a world in which all humans looked the same and were indistinguishable between sexes. That is the confusing case of the monomorphic white stork (Ciconia ciconia). Since 1989 a breeding project has been in place to re-establish the white stork in Sweden. The project has been largely successful.

In conservation biology such as the Stork Project determining sex is essential for studying population dynamics and migrations patterns. Researchers are now facing a problem as these large birds look identical. At present, the sexing of storks is done through DNA analysis of blood or tissue samples. However, storks do vary in size and it seems males are, in general, larger than females. Investigating the differences in body size of the white stork might therefore be important in developing a method of identifying sex using non-invasive techniques.

The aim of this study was to find a method of sexing the white stork using biometric measurements of the skull-bill (SKBL) and tarsus (TRS). Measurements from living birds were previously recorded by the Stork Project (Ola Olsson) and were made available to this study. Many of the birds included in the live data had since passed and were accessible for skeletal measurements at the Biological Museum, Arkivcentrum Syd. This allowed for comparison of live and skeletal material of the same individual birds. The storks were carefully measured to the nearest five millimeters for tarsus length and to the nearest one millimeter for skull-bill length. Only measurements from birds last measured alive at one year or older were used to ensure that the storks were fully grown at the time of death.

Data analysis proved that male storks are, not unlike humans, significantly bigger headed and longer legged than females. Figure 1 illustrates the sexual size difference in both living and non-living birds. There is an overlap where larger females intersect smaller males. Still, it can be concluded that white storks can be sexed using biometric measurements of the skull, bill and tarsus.

Examensarbete för kandidatexamen i Biologi 15 hp 2020
Biologiska institutionen, Lunds universitet.
Handledare: Ola Olsson
Principal Investigator at BECC – Biodiversity and Ecosystem services in a Changing Climate. (Less)
Please use this url to cite or link to this publication:
author
Witt, Karin
supervisor
organization
course
BIOK01 20201
year
type
M2 - Bachelor Degree
subject
language
English
id
9021576
date added to LUP
2020-06-23 11:28:20
date last changed
2020-06-23 11:28:20
@misc{9021576,
  author       = {{Witt, Karin}},
  language     = {{eng}},
  note         = {{Student Paper}},
  title        = {{Sex identification of white storks (Ciconia ciconia) using biometric measurements of the skull, bill and tarsus}},
  year         = {{2020}},
}