Assessment of two methods for estimating Little Bittern Ixobrychus minutus populations in fluvial habitats in Central Spain

Research output: Contribution to journalArticle

Abstract

Two techniques for estimating the relative abundance and density of Little Bitterns Ixobrychus minutus were compared for three stretches of the river Tormes (Salamanca, central Spain). Transects consisted of counting the number of breeding individuals detected when walking at 1 km/h along the river bank, whereas during the point-station methodology bird behaviour was recorded and territories mapped for 30 minutes every 250 meters of riverbank. Estimations
of relative abundance expressed in terms of the number of pairs/hour sampling effort were 29% higher for the point-stations than for the transects, highlighting the greater efficiency of the point-stations. Due to differences in the sampling effort, the point-station method detected 2-3 times more territories than the transects, thereby indicating that the standardised sampling efforts (1 km/h) used in the transects seriously underestimated the total number of breeding pairs. The point-station method could play in the future an important role in Little Bittern studies, although further analysis of its performance is still required.
Original languageEnglish
Pages (from-to)54-58
Number of pages5
JournalRevista Catalana d’Ornitologia
Volume25
Publication statusPublished - 2009

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Spain
habitats
rivers
breeding
methodology
sampling
walking
Ixobrychus minutus
birds

Keywords

  • little bittern
  • Ixobrychus minutus
  • ardeidae
  • density
  • survey methods
  • Central Spain

Cite this

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title = "Assessment of two methods for estimating Little Bittern Ixobrychus minutus populations in fluvial habitats in Central Spain",
abstract = "Two techniques for estimating the relative abundance and density of Little Bitterns Ixobrychus minutus were compared for three stretches of the river Tormes (Salamanca, central Spain). Transects consisted of counting the number of breeding individuals detected when walking at 1 km/h along the river bank, whereas during the point-station methodology bird behaviour was recorded and territories mapped for 30 minutes every 250 meters of riverbank. Estimationsof relative abundance expressed in terms of the number of pairs/hour sampling effort were 29{\%} higher for the point-stations than for the transects, highlighting the greater efficiency of the point-stations. Due to differences in the sampling effort, the point-station method detected 2-3 times more territories than the transects, thereby indicating that the standardised sampling efforts (1 km/h) used in the transects seriously underestimated the total number of breeding pairs. The point-station method could play in the future an important role in Little Bittern studies, although further analysis of its performance is still required.",
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T1 - Assessment of two methods for estimating Little Bittern Ixobrychus minutus populations in fluvial habitats in Central Spain

AU - Garcia Diaz, Pablo

PY - 2009

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AB - Two techniques for estimating the relative abundance and density of Little Bitterns Ixobrychus minutus were compared for three stretches of the river Tormes (Salamanca, central Spain). Transects consisted of counting the number of breeding individuals detected when walking at 1 km/h along the river bank, whereas during the point-station methodology bird behaviour was recorded and territories mapped for 30 minutes every 250 meters of riverbank. Estimationsof relative abundance expressed in terms of the number of pairs/hour sampling effort were 29% higher for the point-stations than for the transects, highlighting the greater efficiency of the point-stations. Due to differences in the sampling effort, the point-station method detected 2-3 times more territories than the transects, thereby indicating that the standardised sampling efforts (1 km/h) used in the transects seriously underestimated the total number of breeding pairs. The point-station method could play in the future an important role in Little Bittern studies, although further analysis of its performance is still required.

KW - little bittern

KW - Ixobrychus minutus

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