Rare bat in the Netherlands

Parti-coloured bat

Translated from Natuurmonumenten in the Netherlands:

Rare bat in Haarzuilens

Posted on October 5, 2010

During a bat-watching excursion in Haarzuilens, the parti-coloured bat Vespertilio murinus has been observed. This relatively large bat is one of the rarest species in the Netherlands.

As many as nine species

In Haarzuilens, in total nine different species of bats have been observed. Some of these species have colonies in the village, in Castle de Haar, in the castle park and the golf course. This makes Haarzuilens one of the richest bat areas in the Netherlands.


Natuurmonumenten organizes each year several bat excursions in Haarzuilens. Accompanied by bat experts, these evening walks are in and around the village Haarzuilens. Using so-called ultrasonic bat detectors, the sounds of bats is converted into tones, audible for humans. Each bat has its own pitch and rhythm, by which the species can be recognized.

Unexpected type

The most common species that is heard is the common pipistrelle, and in addition, also often Nathusius’s pipistrelle, serotine bat and common noctule, sometimes brown long-eared bat and Daubenton’s bat are observed.

Unmistakably a parti-coloured bat!

The parti-coloured bat is a rare appearance in the Netherlands. In 1977 this species was discovered for the first time. In later years, the species was observed sporadically in autumn and winter, especially near the coast. It was thought that these were vagrants. That view became untenable in 1998 when in the district Maarssenbroek in Utrecht a parti-coloured bat maternity colony was found.

England: September 2010. The first survey into the night-time wildlife at the Forestry Commission’s Weston & Waverly Woods has revealed that the forest is a popular hang-out for bats: here.

The use of different resources by males and females exacerbates the estimation of population sizes. However, the monitoring of population sizes, particularly for rare and threatened species, is pivotal to quick and effective conservation action. Scientists from the Max Planck Institute for Ornithology in Radolfzell investigated the ecological niches of male and female parti-colored bats (Vespertilio murinus) and found out that the sexes use entirely different foraging grounds. With their results they can show that a finer grained view of what different demographic subsets of species do is essential for correct estimation of population trends with important implications on action plans for conservation: here.