Bats play an important role in the environment by consuming large amounts of insects and acting as pollinators. Sixteen bat species are found in the Netherlands, but some populations have declined due to loss of habitat from building renovations. Providing bat boxes is a way to create new housing for bats and preserve bat populations. Common bat species suitable for bat boxes include pipistrelle bats, serotine bats, and pond bats. Birds also consume insects and providing housing helps optimize the ecosystem. Some vulnerable bird species found in Noord-Brabant could potentially nest in the polliblocks.

1. Bats
Bat Benefits
All Dutch bat species are insect-eaters and are therefore regarded as very useful for the
environment. (BAT, n.d.) In fact, one bat consumes an average of 3000 insects per night!
(Blokker & Timmermans, 2018) Due to their diet, bats are a great natural pest control, as they
feed on food-eating pests such as caterpillars and beetles. (Faidley, 2020)
Apart from maintaining a balanced ecosystem, and eating mosquitoes, bats are one of
the most important pollinator species. As the only flying mammal, bats spread seeds,
fertilizer and nectar, allowing our food and plants to grow. (Faidley, 2020)
Bat Species in the Netherlands
Europe houses roughly 50 different bat species, of which 16 are currently found in the
Netherlands. (Mei & Dijkstra, 2011) This number used to be higher, however, after the
Second World War, their number reduced mainly due to the use of pesticides on a large
scale.
Three bat species (the Western Barbastelle, the Greater horseshoe bat and the Lesser
horseshoe bat) have completely disappeared from the Netherlands, and one (the
mouse-eared bat) still hibernates but does not breed in the Netherlands. (Mei &
Dijkstra, 2011)
The Dutch Mammal Society monitors 8 bat species. Three species (Geoffroy’s,
Natterer’s and grey long-eared bats) are growing most rapidly, as seen in figure x.
(around 10% annual increase) (Mei & Dijkstra, 2011) Geoffroy’s and Grey long-eared
bats are rare and only found in the south of the Netherlands, while Natterer’s bats are
quite common across the entire country. However, the long-eared is nowadays more
commonly found elsewhere.
The bat populations that have grown the least are Pond bats (3% annually) and the
population of Daubenton’s bat has decreased since 2006.
Although they are a common species, the pipistrelles bats are not monitored, as they
live in small, nearly inaccessible hideouts.
Damage from Bats
Bats do not cause any direct damage. ‘They don’t chew on things, nor do they spread
diseases. They could carry rabies, but bats do not go crazy or bite without reason.
Should you be bitten by a bat or you held a bat when you have a wound on your hand,

2. you should get a rabies shot from the general practitioner’. (BAT, n.d.) However only 3
species of bats carry rabies, and they are only found in Central and South America.
(Faidley, 2020)
Suitable Species for the Polliblocks
Currently, many bats like to inhabit crevices and spaces such as wall cavities in
buildings. However, due to the renovation of old buildings that contain these cavities
(filling up the cavities, and openings etc), roosting opportunities for bats are
disappearing. (Korsten, Limpens, Bouman, & Reinhold, 2011)
In order to make buildings more energy efficient and to cut energy costs, filling in these
cavities with insulation is important for the environment. However, a solution needs to
be found in giving back the bats their home in an alternative way.
Spaces for maternity roosts and hibernacula need to be a lot bigger (at least 0.7m2
surface area) This size is too large and expensive for the target group that is aimed at
for the chosen intervention.
Although small boxes (0.2-0.4m2 surface area) are not good enough for maternity
roosts/hibernacula, putting up bat boxes is the simplest way to provide new roosts, and
it is a method of preserving bats that anyone is able to perform. (Korsten, Limpens,
Bouman, & Reinhold, 2011)
Bat Species suitable to live in the Polliblocks include: Common pipistrelle, Nathusius’s
pipistrelle, Serotine bats, Particoloured bats and Pond bats (Blokker & Timmermans, 2018)
Some requirements for the bat boxes include: avoiding birds taking over bat spaces by ensuring
the entrance opening is between 17-20mm for Pipistrelles and 20-25mm for other species,
ensuring southwest orientation of the boxes, so they gain enough heat, and placing plants
underneath the boxes, so that the droppings don’t have to be cleaned, rather used as fertiliser.
Birds
In Noord-Brabant, there are currently 335 recorded species of birds, of which 10 have
been introduced, and 14 are threatened. (Lepage, 2020)
Bird Benefits
Just like bats, birds also consume insects. However, unlike bats, birds live during the
day and sleep at night. Giving both birds and bats a home to live in, helps improve and
optimize the overall ecosystem.
Bird Species in NL
Some of the common bird species found in the Netherlands include: Sparrows, Swifts,
House Martins, Barn Swallows, Starlings, White wagtails, Black redstart and Peregrine
falcons.

3. In table x, the vulnerable species are displayed, and the species that can nest in the
Polliblocks are highlighted. However, it is difficult to choose which species inhabits the
polliblocks, as the birds are of similar size. The openings for the bird boxes vary in size,
to accommodate a species that is lacking in the region (small(sparrow size)-
medium(dove size))
Table 1- vulnerable bird species seen in Noord-Brabant
Noord-Brabant bird population
Species type Vulnerable
Anatidae Red-breasted Goose
Anatidae Lesser White-fronted Goose
Anatidae Long-tailed Duck
Anatidae Common Pochard
Podicipedidae Slavonian Grebe
Columbidae European Turtle Dove
Alcidae Atlantic Puffin
Laridae Black-legged Kittiwake
Acrocephalidae Aquatic Warbler