Focus

    Rails: secretive life between water and land

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    Typical rail habitat with dense vegetation dominated by sedges and water about 40 cm deep. Almost the entire habitat is covered by water. © Martin Schuck

    Rails are found in the shallow-water zones of wetlands. They tend to inhabit dense vegetation, so acoustic communication plays a vital role. The three small rail species that occur in Switzerland are rare. Their nocturnal song and secretive behaviour make surveys difficult .

    The three small rail species Spotted Crake, Little Crake and Baillon’s Crake are patchily distributed in central Europe, their core ranges lying further to the east. Their habitat – wetlands such as marshes, flooded sedge meadows, and silted-up areas – has been drained and reduced in size in the past 200 years. Mires lost 82 % of surface area in Switzerland between 1900 and 2010, alluvial plains 36 %. The remaining wetlands are scattered and exposed to a number of adverse influences. Still today, low water levels during the breeding season due to ditches and other drainage measures lead to the degradation of many potential breeding sites in Switzerland. Suitable habitats do not necessarily have to be large in size, as all three species can colonise wetlands of less than 1 ha if conditions are favourable.

    Singing activity in suitable habitats is generally an indication of individuals looking for a mate, as rails rarely sing during migration. In 2013–2016, 9–13 Spotted Crake territories and 1–2 Little Crake territories were recorded annually in Switzerland. As for the Baillon’s Crake, only one territory was found in 2012 and in 2017; in 2016, there was a single observation during the breeding season. How many territories might have been overlooked?

    Number of territories recorded annually from 1990 to 2016 for Spotted Crake, Little Crake and Baillon’s Crake in Switzerland.

    On the one hand, these secretive marsh birds are rare and irregular visitors; on the other hand, recording them by visual or acoustic means is a challenge. Visual observations mainly take place during migration, when all three species use the edges of reedbeds as stopover sites. During the breeding season, they generally remain well hidden in dense vegetation. Singing activity mostly takes place at dusk and during the night. In some larger wetlands where the birds are regularly recorded, observers annually conduct 1–2 evening surveys beginning at dusk. But in the rest of the 90 wetlands that are systematically monitored and at other potential breeding sites, there are no such special surveys. Monitoring is further complicated by the fact that males only sing regularly until they have found a mate or the eggs have been laid.

    The current methods probably only enable us to detect a part of the actual territories. More intensive monitoring, for instance by means of standardised nocturnal surveys or using acoustic recording devices, would improve our understanding of the extent to which these species occur.

    Text: Claudia Müller & Martin Schuck


    Recommended citation of the Atlas online:
    Knaus, P., S. Antoniazza, S. Wechsler, J. Guélat, M. Kéry, N. Strebel & T. Sattler (2018): Swiss Breeding Bird Atlas 2013–2016. Distribution and population trends of birds in Switzerland and Liechtenstein. Swiss Ornithological Institute, Sempach.

    References

    BAFU (2017): Biodiversität in der Schweiz: Zustand und Entwicklung. Ergebnisse des Überwachungssystems im Bereich Biodiversität, Stand 2016. Umwelt-Zustand Nr. 1630. Bundesamt für Umwelt (BAFU), Bern.

    del Hoyo, J., A. Elliott, J. Sargatal, D. A. Christie & E. de Juana (2017): Handbook of the birds of the world Alive. Lynx Edicions, Barcelona. https://www.hbw.com (22.11.2017).

    FOEN (2017): Biodiversity in Switzerland: status and trends. Results of the biodiversity monitoring system in 2016. State of the environment no. 1630. Federal Office for the Environment (FOEN), Bern.

    Fox, A. D., J. P. Kjeldsen, M. Desholm, P. A. F. Rasmussen, T. J. S. Balsby & H. Heldbjerg (2014): Within and between year phenology of calling Spotted Crakes Porzana porzana in Denmark. Wildfowl 64: 102–115.

    Glutz von Blotzheim, U. N. & K. M. Bauer (1966–1997): Handbuch der Vögel Mitteleuropas. Bd. 1–3 von K. M. Bauer & U. N. Glutz von Blotzheim bearbeitet, Bd. 4–7 von U. N. Glutz von Blotzheim, K. M. Bauer & E. Bezzel sowie Bd. 8–14 von U. N. Glutz von Blotzheim & K. M. Bauer. Mehrere Bände seither in der 2., durchges. Aufl. Akademische Verlagsgesellschaft, Wiesbaden (bis 1982) bzw. Aula, Wiesbaden.

    Lachat, T., D. Pauli, Y. Gonseth, G. Klaus, C. Scheidegger, P. Vittoz & T. Walter (2010): Wandel der Biodiversität in der Schweiz seit 1900. Ist die Talsohle erreicht? Bristol-Schriftenreihe Bd. 25. Bristol-Stiftung, Zürich, und Haupt, Bern.

    Lachat, T., D. Pauli, Y. Gonseth, G. Klaus, C. Scheidegger, P. Vittoz & T. Walter (2011): Evolution de la biodiversité en Suisse depuis 1900. Avons-nous touché le fond? Collection Bristol vol. 25. Fondation Bristol, Zurich, et Haupt, Berne.

    OFEV (2017): Biodiversité en Suisse: état et évolution. Synthèse des résultats de la surveillance de la biodiversité. État: 2016. État de l'environnement n° 1630. Office fédéral de l'environnement (OFEV), Berne.

    Schäffer, N. (1999): Habitatwahl und Partnerschaftssystem von Tüpfelralle Porzana porzana und Wachtelkönig Crex crex. Ökol. Vögel 21: 1–267.

    Taylor, B. & B. van Perlo (1998): Rails. A guide to the rails, crakes, gallinules and coots of the world. Pica Press, Mountfield.

    UFAM (2017): Biodiversità in Svizzera: stato ed evoluzione. Risultati del sistema di monitoraggio della biodiversità, stato 2016. Stato dell'ambiente n. 1630. Ufficio federale dell’ambiente (UFAM), Berna.

    Species concerned
    Subject
    Waters and wetlands
    Population monitoring
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