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EcoSolutions Integrated Pest Management
Service Report for May 2016
Overview:
It has been suggested that bats are restricted in their ability to contribute to arthropod
suppression within the agricultural sector primarily due to the lack of available and
suitable roost sites. (Long et al., 2006; Taylor, 2000). The provision of artificial roost
sites in the form of bat boxes, bat towers or bat Hotels have been attempted since the
early 20th century (Campbell, 1925; Tuttle et al., 2004), and has produced mixed
results. Bats have shown an acceptance for some of these artificial structures and a
resistance to others.
Although some research has been undertaken on the
parameters which make these structures appealing or unappealing to bats (Long,
Kiser & Kiser, 2006; Tuttle, Kiser & Kiser, 2004; Vonhof & Barclay, 1996) there is still
a need for further research. The implementation of artificial roost sites with the Levubu
and Tzneen areas are in an attempt to establish occupancy potential and additionally
to ascertain the feasibility of insectivorous bats being utilised in the control of stink
bug, a agricultural pest prevalent in the area (Taylor.. ) Below is the May 2016 service
report.
The service undertaken by EcoSolutions in May 2016 was primarily to re-treat bat
houses and to check for occupancy and additionally, possible site selection
preference. In addition, EcoSolutions installed guano trays at the bat banks and
installed prototype rocket bat boxes to ascertain their potential for future occupancy.
Although covered in the report, for ease of reference, the important observations are
bulleted below.
• All of the Bat houses serviced in Levubu during May 2016 are either occupied, or
show signs of occupancy.
• The guano trays indicated bat occupancy in the form of guano beneath the bat
houses 30 minutes after installation. This occupancy was recorded in bat houses
that had previously been viewed as unoccupied. All sites should utilise guano trays
as a matter of course.
• We have provided an interactive map, showing sites, occupancy, orientation and
elevation. We are able to update and manage this map from our offices and all
participating farmers and interesting parties are welcome to add to this platform.
Please contact EcoSolutions for editing capabilities.
• The method of ascertaining bat house occupancy through the use of mirrors and
torches appears to have real limitations.
• The importance of an available water source for bats and for bat houses placement
was a consideration at the installation stage of this project. The map provides
distance to water information as does this report.
• The service of the bat houses remains an essential component to successful
occupancy.
• In our conclusion we suggest the service of other bat houses in this programme as
soon as possible. At this service, both Guano trays and rocket boxes should be
incorporated.
Bat Occupancy for May 2016 on farms in the Levubu Region:
Number (n) of individual bats in occupied bat boxes for May 2016 on farms in
the Levubu Region:
Farm Name:
Muirhead & Roux
Type of Box
Bank Site 1 Bank Site 2 Slimline Site
Coordinates
23°03’20’’S 23°03’12’’S 23°03’12’’S
30°08’58’’E 30°08’26’’E 30°08’55’’E
6-Chamber
n (2)
n (6)
Nursery
n (3)
n (1)
Rocket Box Rocket Box
Site 1
Site 2
23°03’20’’S 23°03’12’’S
30°08’58’’E 30°08’55’’E
Old George
Slimline
Guano
Newly
stalled
Rocket Box
Total
n (5)
n (7)
Unconfirmed
None
In- Newly
stalled
None
In-
Farm Name:
Amana
Bank Site 1 Bank Site 2 Slimline Site
Rocket Box Rocket Box
Site 1
Site 2
23°06’49’’S 23°06’40’’S 23°06’43’’S
23°06’49’’S 23°06’40’’S
Coordinates
30°17’27’’E 30°17’23’’E 30°17’17’’E
30°17’27’’E 30°17’23’’E
6-Chamber
n (3)
Nursery
n (6)
Old George
3 Bush- ban (2)
bies
Type of Box
n (4)
Slimline
Guano
Newly
stalled
Rocket Box
Total
n (9)
n (6)
Unconfirmed
None
In- Newly
stalled
None
In-
Farm Name:
Integrifolia
Type of Box
Rocket Box Slimline Site Slimline Site
Bank Site 1 Bank Site 2 Site
1
2
23°05’01’’S 23°05’25’’S 23°05’01’’S 23°05’14’’S
23°05’12’’S
Coordinates
30°20’59’’E 30°20’26’’E 30°20’59’’E 30°20’49’’E
30°20’49’’E
6-Chamber
n (4)
Nursery
n (12)
Old George
n (2)
Slimline
Guano
Newly
stalled
Rocket Box
Total
n (4)
n (14)
None
Guano
In-
Unconfirmed Unconfirmed
A total number of 45 individual bats was recorded in May 2016.
Occupancy and Bat Box Orientation:
Bird and bat species may select their nesting sites in specific locations and orientations. This can maximise their chances to successfully breed. For example, east-facing nesting sites are warmed in the morning, south-facing ones receive the most
amount of sunlight, and north-facing ones receive the least.
At each site, the orientation of the bank box sites and slimline box sites were noted
based on the direction the entrance of the bat house was facing. Rocket box sites are
open at the bottom, therefore, the orientation is invalid.
The individual bat numbers relating to the orientation of the bank sites are represented
below.
Bat Occupancy of Bank Sites Related to Orientation
Orientation
Number of Bank Boxes
Individual Bat Occupancy
North East
33%
n (16)
West
17%
n (5)
South West
17%
n (6)
South
17%
n (4)
South East
17%
n (14)
Number of Bank Boxes
South East, 1, 17%
North East, 2, 33%
South , 1, 17%
South West, 1, 17%
North East
South
West, 1, 16%
West
South East
South West
Individual Bat Occupancy
South East, 14,
31%
North East, 16, 36%
South , 4, 9%
West, 5, 11%
South West, 6, 13%
North East
West
South
South East
South West
Occupancy and Distance to Water
Bat Occupancy of Bank Sites relating to their Distances to Water
Distance
Bank Site Boxes within
each Distance Range
Individual Bat Occupancy
<50m
33%
n (14)
50m-100m
17%
n (7)
100m-500m
33%
n (10)
>500m
17%
n (14)
Bank sites occupancy and distance to water
>500m, 14, 31%
<50m, 14, 31%
50m-100m, 7, 16%
100m-500m, 10,
22%
<50m
50m-100m
100m-500m
>500m
Occupancy
Occupancy was recorded at all bat bank sites. Preference was recorded for the
Nursery and 6 chamber bat house design. The “Old George”, a popular bat house
design from the USA, has only recorded occupancy at one site with 2 individual bats
observed. In one of the “Old George” boxes, a family of bush babies was recorded.
The lack of occupancy in the “Old George” boxes may well be a result of the more
intricate sleeve design within the box which makes bat observation difficult.
Recording occupancy within the slimline boxes is difficult. The single chamber and
thickness of the box makes visual inspection very difficult. The presence of Guano
beneath these boxes indicators the presence of bats either currently or in the past.
The mounting of guano trays to the walls beneath the slimline bat houses should be
undertaken during the next service visit.
Artificial roost sites are used in various ways by different bat species, as well as by
individuals of the same species. Bat houses may be used as maternity roosts, hibernacula, bachelor roosts and nocturnal “resting” roost sites. The requirement parameters between a maternity roost site and a ‘resting” site during a night of hunting, will
differ. Bats are also known to move from one roost site to another as a consequence
of predation pressure (the roost has been identified and is frequently visited by a predator of bats, i.e. a cat, or genet), by parasite pressure (increased mite and or lice numbers), or proximity to prey (bats will move to sites with higher insect numbers for consecutive nights in order to maximise feeding opportunity). It is for these reasons, in
conjunction with box design preference, that different box designs were used in the
Levubu, Tzaneen projects.
The interactive map shows all occupancy recorded as at the May 2016 service.
Guano collection trays
The guano trays at all of the bat banks were installed by EcoSolutions as part of our
Research and development undertaking. The value of these guano trays was quickly
established. Trays under bat houses classified as unoccupied, within 30 minutes of
the tray installation, were reclassified as occupied. Guano was collected from beneath
the boxes almost immediately, indicating the presence of bats therein. The lack of
provision of guano trays at the bat houses at the time of installation was an oversight
and should be corrected as soon as possible. The value of the guano trays are twofold:
• The presence of guano indicates to farmers who visit the site that the bat houses are
occupied without ladders, mirrors and torches.
The collected guano can also be used for DNA markers, which eases the identification
of bat species occupying bat box sites. Trays are especially valuable to the Slimline
Box set-up, due to its design inherently limiting visual inspection. The only Slimline
Sites where no guano was recorded were on the Integrifolia Sites. The absence of bat
occupancy on the Integrifolia Slimline Sites is explained by the newly-erected fence,
that was placed one metre from the boxes. The
close proximity of the fence to the Slimline
Boxes may restrict access of the box by bats.
Rocket Boxes were installed on all farms in the
Levubu region as a prototype bat box. The design of the Rocket Box allows access for bats
from all directions, therefore orientation becomes arbitrary.
From the above data and graph, there is a relatively even distribution of bat occupancy regarding the ranges of distances to water for
each Bank Site. The greatest percentage of
bat occupancy to distance from water is shared between the closest range, being below 50 m to the closest water source, and the farthest range, being over 500 m to the
closest water source. This indicates to no significant differentiation between distances
to water and bat occupancy of bat box sites.
The data collected in the May 2016 inspection is valuable, especially when looking at
the number of individual bats and their distance to the closest water source, due to the
data being distributed evenly and thus no significant correlation is found. Further, a
clear preference is displayed by individual bats choosing east-facing bat boxes. Lastly,
the importance of utilising guano trays is obvious, because it creates a means to record bat occupancy especially with Slimline Sites and provides a method of identifying
bat species from bat box sites.