Preventing crop raiding by the Vulnerable common hippopotamus Hippopotamus amphibius in Guinea-Bissau
←
→
Page content transcription
If your browser does not render page correctly, please read the page content below
Preventing crop raiding by the Vulnerable
common hippopotamus Hippopotamus amphibius
in Guinea-Bissau
LUIS M. GONZÁLEZ, FRANCISCO G. D. MONTOTO, TOME MERECK, JUNIOR ALVES
JOSÉ PEREIRA, PABLO FERNÁNDEZ DE LARRINOA, ANA MAROTO
L U I S B O L O N I O and N U R I A E L - K A D H I R
Abstract Guinea-Bissau is host to the westernmost subpo- protection, such as killing the wild animals involved in
pulation of the common hippopotamus Hippopotamus crop raiding, are limited, and thus human−wildlife conflict
amphibius, which is one of only two known populations in- jeopardizes the efficacy of protected areas by undermining
habiting coastal waters. The presence of hippopotamuses local support for conservation (Fungo, ). To resolve
causes conflict with rice farmers as a result of crop damage the conflict, wildlife managers usually mitigate the crop raid-
and the absence of effective measures to protect crops. To ing activities of wild animals; for example, by scaring animals
develop an effective method for protecting rice fields, we away from crops, using scare-shooting and barriers, or com-
studied the patterns of access to flooded and rain-fed rice pensating farmers for crop loss. However, the latter measure,
fields by hippopotamuses and assessed the effect of the in- particularly when it involves cash payments, is open to
stallation of electric fences. Hippopotamuses were detected corruption and some farmers may be less likely to improve
in % of the flooded fields (n = ) and in .% of the their management practices or adopt new ones to reduce
rain-fed fields (n = ). They were detected more frequently conflict. Thus, bad managers may be compensated at the ex-
in fields on offshore islands than on the mainland, in un- pense of those who invest in good management techniques
fenced than in fenced fields, and in fields closer to running on their own initiative (Woodroffe et al., ; Fungo, ).
water. Hippopotamuses entered fenced flooded fields less The common hippopotamus Hippopotamus amphibius,
frequently than unfenced, and were detected most frequently categorized as Vulnerable on the IUCN Red List (Lewison
at the end of the rainy season and the start of the dry season, & Oliver, ), is a major source of human−wildlife con-
and in the period of vegetative stem growth. Electric fences flict in Africa. It causes damage to crops and attacks people
were an effective deterrent and facilitated increased rice pro- (Mkanda, ; Kendall, ). The decline of the species has
duction. The maintenance and cost of the electric fencing been attributed to killing of hippopotamuses by farmers,
were acceptable to farmers, and therefore the use of such fen- and the loss of grazing grounds as a result of agricultural de-
cing is recommended to resolve the conflict between hippo- velopment (Eltringham, ; Lewison & Oliver, ).
potamuses and farmers in Guinea-Bissau and in other areas The hippopotamus population in Guinea-Bissau is the
with similar conditions. westernmost population (Eltringham, ) and is one of
only two known populations to use seawater and inhabit
Keywords Common hippopotamus, crop raiding,
coastal areas (the other is the subpopulation in Loango
electric fence, Guinea-Bissau, Hippopotamus amphibius,
National Park, Gabon; Limoges & Robillard, ; Michez,
human−wildlife conflict, rice fields
). During the th century the hippopotamus became
rare in Guinea-Bissau, where it was considered to be a game
species. The decline has been linked to shooting of hippo-
Introduction potamuses in retaliation for crop damage; for example, in
the region of Cacheu during − hippopotamus
deaths resulted from conflict with farmers (Lopes, ).
C rop raiding by wild animals results in substantial finan-
cial losses for farmers living in proximity to wildlife.
When wildlife is protected, traditional means of crop
In – the hippopotamus was declared a protected
species in Guinea-Bissau and two protected areas with
hippopotamus populations were established: Orango
National Park and Cacheu Natural Park (IBAP, ).
LUIS M. GONZÁLEZ (Corresponding author) and FRANCISCO G. D. MONTOTO
Subdirección General de Medio Natural, Ministerio de Medio Ambiente, There are estimated to be c. individuals in Cacheu,
Plaza San Juan de la Cruz s/n, Madrid 28071, Spain – in Orango and – in the areas of Bissorao and
E-mail lmgonzalez@magrama.es
Carantaba (Lopes, ; Silva & Monteiro, ; IBAP,
TOME MERECK, JUNIOR ALVES, JOSÉ PEREIRA, PABLO FERNÁNDEZ DE LARRINOA, ANA ; Silva, ).
MAROTO, LUIS BOLONIO and NURIA EL-KADHIR Fundación CBD-Hábitat,
Madrid, Spain Hippopotamuses require large areas of savannah grass-
Received June . Revision requested July . lands, where they feed on stems of herbaceous species,
Accepted August . First published online January . and in times of food stress they will also feed in cultivated
Oryx, 2017, 51(2), 222–229 © 2016 Fauna & Flora International doi:10.1017/S003060531500109X
Downloaded from https://www.cambridge.org/core. IP address: 46.4.80.155, on 23 Sep 2021 at 23:33:30, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms
. https://doi.org/10.1017/S003060531500109X
Preventing crop raiding by hippopotamus 223
FIG. 1 Locations of the rice fields (black
filled circles) studied in Cacheu Natural
Park, Bissorao and Carantaba, on
mainland Guinea-Bissau, and in the
Orango Islands National Park and Uno
Island, with the hippopotamus
Hippopotamus amphibius resting places
(filled white circles) identified in
previous studies (Silva, ).
rice fields if available (Eltringham, ; Kendall, ). Rice is not sustainable, and shooting has not been effective in
production is one of the main economic activities of the minimizing crop damage in other countries with similar
rural population of Guinea-Bissau and is the most import- problems (Mkanda, ; Fungo, ), and may cause hippo-
ant livelihood activity for people in the protected areas of potamuses to become more aggressive (Eltringham, ).
Orango and Cacheu (Alves & Barros, ; Medina, ). The hippopotamus is a charismatic species that attracts tour-
Past surveys with farmers in Guinea-Bissau showed that ists and has the potential to generate significant foreign cur-
hippopotamuses were responsible for a significant reduction rency income. In this context the management plans of
in rice production and caused significant economic losses Orango and Cacheu protected areas, developed in consult-
(Lopes, ; Medina, ; Silva, ). They also have in- ation with local people, prioritize the assessment of mitiga-
direct effects, such as restricting people’s movements and tion measures to resolve the conflict (Campos et al., ;
causing accidents and deaths. In the th century people IBAP, ).
were injured and killed by hippopotamuses in Orango The behaviour of hippopotamuses in response to protec-
and Cacheu as a result of boat sinking or while guarding tion measures has not been well studied (Eltringham, ).
rice fields, and hippopotamuses are thus widely perceived To address human−hippopotamus conflict it is necessary to
to be one of the major threats to the security and livelihoods consider both the patterns and effects of the damage as well
of rural people, and inspire animosity and fear (Lopes, ; as the impacts of mitigating actions on the conservation sta-
Campos et al., ; IBAP, ). Consequently the rice tus of the hippopotamus. With the aim of contributing to
fields situated near water courses inhabited by hippopot- resolving the conflict between hippopotamuses and rice
amuses have progressively been abandoned in favour of farmers in Guinea-Bissau, we investigated access to rice
rice fields located within forested areas, and this is contrib- fields, and evaluated the effectiveness of a protective meas-
uting to increases in deforestation and biodiversity loss ure (electric fencing), hippopotamus behaviour in response
(Vasconcelos et al., ; Medina, ). to this measure, and the feasibility of its use by local farmers.
To prevent hippopotamuses from entering rice fields, We propose practical and feasible measures to solve the con-
farmers in Guinea-Bissau have been using barbed-wire flict between people and hippopotamuses.
fences, embankments and ditches, and night watchmen
with fires and weapons. However, because of their high
cost, complex maintenance or safety hazards these methods Study area
have not been successful (Lopes, ; Campos et al., ;
Silva & Monteiro, ; Medina, ). Electric fencing, The study was conducted in the Orango Islands National
which is used effectively in other countries (Eltringham, Park (, ha; IBAP, ) and Uno Island in the
), has not been previously tested in Guinea-Bissau. Al- Bijagos archipelago, in Cacheu Natural Park (, ha;
though farmers in protected areas have requested compen- IBAP, ), in Bissorao in the region of Oio, and in
sation, or elimination of hippopotamuses, the wildlife Carantaba in the region of Gabu (Fig. ). Henceforth the
authorities have not considered either option. Compensation term Orango includes Uno Island.
Oryx, 2017, 51(2), 222–229 © 2016 Fauna & Flora International doi:10.1017/S003060531500109X
Downloaded from https://www.cambridge.org/core. IP address: 46.4.80.155, on 23 Sep 2021 at 23:33:30, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms
. https://doi.org/10.1017/S003060531500109X224 L. M. González et al.
The climate is tropical, with a rainy season during fences, unfenced flooded fields and unfenced rain-fed
May−October in the Bijagos and during June−October on fields (Table ). We recorded the location and area of each
the mainland. The dry season is December−April in the rice field using a global positioning system to an accuracy of
Bijagos and December−May on the mainland. The mean m. We also measured the distance of each field to the near-
annual rainfall is , mm in the Bijagos and ,–, est running water. All fields were unguarded by night watch-
mm on the mainland, and the mean annual temperature is men during the study period. The number of fenced fields
.°C; both parameters were stable during the study period, increased each year. The electric fence equipment was re-
with no drought years (Medina, ; CCKP, ). tired each year after the end of the harvest and installed
The dominant vegetation in the study area consists of a again the following year in the same field, until the end of
mosaic of tropical dry forest and tree and shrub dry savan- the study period. During the period of rice cultivation
nah, with sub-humid isolated and flooded herbaceous each year, the perimeter and interior of fenced fields
savannah (Catarino et al., ). Two types of rice fields was monitored daily by the farmers. In addition, we
were included in the study: flooded and rain-fed. The surveyed the fenced and unfenced fields every − days dur-
flooded fields, known locally as bolanha and bas-fond, are ing this period to search for hippopotamus footprints.
flooded by river run-off and are located in the humid savan- Information on hippopotamus presence in rain-fed fields
nah and alluvial depressions. The water is retained and was provided by farmers at the end of the growing season,
regulated by a system of dykes with drainage channels. having been verified by protected area wardens.
Management is communal, with each field divided into We recorded hippopotamus detection without entry if
owned plots (Biai, ; Medina, ). The long-cycle we observed footprints only on the perimeter, and with
rice seed (-day seed) and occasionally the short-cycle entry if the footprints were in the interior of the field. The
seed (-day seed) are used. Sowing begins after water location and date were recorded for each footprint, to avoid
reaches the maximum retainable level, and the rice growth duplication. The hippopotamus populations of Orango and
depends on the amount of water available in the soil. The Cacheu are isolated and, according to annual monitoring by
duration of the crop in each area varies depending on wardens, hippopotamuses occupied the same areas during
when the rainy season begins (Medina, ). In Orango, the study period as in previous studies (Lopes, ; Silva,
during the study period, sowing began in July–August and ; IBAP, ; Fig. ).
harvesting in December–January; in Cacheu, sowing started We estimated the rice productivity (kg ha−) in each field
in June–July and harvesting in December; and in Bissorao by interviewing the farmers and recording the number of
and Carantaba, sowing began in August–September and bags of rice produced each season (each bag weighing
harvesting in December–January. c. kg) and the number of families working the fields. In
The rain-fed fields, known locally as mpam-mpam, are Orango we interviewed , , and farmers during
located in non-flooded lands, in forested areas where the –, respectively; on the mainland we interviewed
vegetation was previously slashed and burned. Each year a and farmers in and , respectively. To
different area of land is prepared, and the same area is cul- avoid overestimation of crop losses, we recorded the area af-
tivated again every – years. The short-cycle seeds are fected, and this information was checked by the wardens of
used most often in these fields. The water comes exclusively the protected areas.
from rainfall, and crop development conforms to the dur- We identified three periods of rice cultivation (sowing,
ation of the rainy season. Sowing normally begins in vegetative shoot growth and harvesting) and five climatic
April–May and harvesting in October–November (Biai, periods (end of the dry season, February–April, , mm
; Medina, ). rainfall per month; start of the rainy season, May–June,
– mm per month; full rainy season, July–September,
. mm per month; end of the rainy season, October–
Methods November, – mm per month; beginning of the dry
season, December–January, , mm per month).
Monitoring of rice fields The electric fence system included an aluminium wire of
. mm diameter, c. cm above the ground, connected to
We conducted enquiries with farmers in Orango in an energizer unit, and a rope between wooden stakes, with
(n = ) and on the mainland in (n = ) to locate strips of red and white striped plastic at intervals of m
rice fields and record their state of cultivation. (Plate ). We used two models of portable energizers with
Subsequently we identified farmers with flooded fields integrated solar panels: Speedrite-Viper S (Tru-Test
who were willing to collaborate with the study and con- Group, Auckland, New Zealand), which powered c. km
sented to the installation of electric fences, and monitoring of wire in Orango, and S, which powered c. km of
of their fields. During – in Orango and – wire on the mainland. In each field two energizers were
on the mainland we monitored flooded fields with electric used simultaneously. The charge was activated and switched
Oryx, 2017, 51(2), 222–229 © 2016 Fauna & Flora International doi:10.1017/S003060531500109X
Downloaded from https://www.cambridge.org/core. IP address: 46.4.80.155, on 23 Sep 2021 at 23:33:30, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms
. https://doi.org/10.1017/S003060531500109XPreventing crop raiding by hippopotamus 225
TABLE 1 Numbers of fenced and unfenced rice fields (flooded and rain-fed) studied in the Orango Islands National Park and Uno Island during −, and on mainland Guinea-Bissau
Rain-fed
0
91
91
Flooded
Total
75
25
100
Rain-fed
No. of rice fields studied on the mainland
0
0
0
Flooded
2013
14
0
14
PLATE 1 The electric fencing system in a flooded rice field in
Rain-fed
Orango (Fig. ), with the energizer unit model S with
integrated solar panel.
0
0
0
Flooded
on only at night. The cost of a complete fencing system with
the S and S energizers was c. EUR and , re-
2012
5
9
14
spectively. The vegetation was cut from within a distance
of – m around the wires twice per week.
Rain-fed
0
0
0
Variables and statistical analyses
Flooded
The rice field was considered to be the experimental unit. To
2011
identify differences in the raiding patterns of hippopot-
25
0
25
amuses we considered two response variables: hippopot-
Rain-fed
amus detection/no detection, and the number of fields
where hippopotamuses were detected. We used the follow-
0
30
30
ing as explanatory variables: the type of field (flooded vs
rain-fed); the geographical location of the field (island vs
Flooded
mainland); the distance to the nearest water body (in m);
2010
the presence/absence of electric fencing; the cultivation
21
0
21
phase (sowing, growth or harvesting); and the climatic per-
iod. To investigate the economic effects of fencing we used
Rain-fed
the following as response variables: the rice productivity of
No. of rice fields studied in Orango/Uno
the field, the number of families working in the field, and the
0
37
37
number of flooded or rain-fed fields. As independent vari-
Flooded
ables we used the presence/absence of electric fencing, and
2009
the year.
6
7
13
As quantitative variables could not be fitted to a normal
distribution we performed non-parametric analysis, using
Rain-fed
as covariates each of the independent variables, with a con-
fidence interval of %. Based on the characteristics of the
0
24
24
response and explanatory variables (categorical or continu-
during − (Fig. ).
ous) we performed various tests: frequency analyses (χ)
Flooded
when response and explanatory variables were categorical,
2008
4
9
13
simple regression analyses for continuous variables, and
Kruskal−Wallis (χ) for comparing mean values of the mul-
Unfenced
tiple (. ) categories of independent categorical variables.
Fenced
To compare the mean annual productivity of fields we
Total
used the same fields before and after the installation of the
Oryx, 2017, 51(2), 222–229 © 2016 Fauna & Flora International doi:10.1017/S003060531500109X
Downloaded from https://www.cambridge.org/core. IP address: 46.4.80.155, on 23 Sep 2021 at 23:33:30, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms
. https://doi.org/10.1017/S003060531500109X226 L. M. González et al.
electric fences (matched pair data), and applied a Wilcoxon
test (Z). Only significant results and those that approached
significance are presented. The analyses were carried out
using Statistica v. . (StatSoft, ).
Results
Monitoring of rice fields
In Orango we located flooded rice fields, .% of them
abandoned. The cause of abandonment was known in
cases: entry of hippopotamuses was the most frequent
cause (%), followed by migration of the human popula-
tion (%) and low rice production (%). In , the
year before electric fences were installed, hippopotamuses FIG. 2 Mean number of flooded rice fields (with % confidence
had entered four of the flooded fields that were cultivated. intervals) in the study areas in Guinea-Bissau (Fig. ) where
On the mainland we located cultivated flooded fields, and hippopotamuses were detected at various periods before, during
in the year before the electric fences were installed () and after the rainy season.
hippopotamuses had entered all of these fields.
Hippopotamuses were detected in .% of fields
(n = ), and the rate of detection was significantly higher
in flooded than in rain-fed fields (%, n = vs .%,
n = , χ = ., P = .). The mean distance of flooded
fields to the nearest running water was m (.–. m, n
= ), and the number of flooded fields where hippopot-
amuses were detected was significantly higher closer to
running water (r = −., P = .).
The number of flooded fields in which hippopotamuses
were detected decreased significantly over the study period
(r = ., r = −., P = .), increased significantly
with the number of times the field was cultivated (r = .,
r = ., P , .), and was significantly higher in Orango
than on the mainland (.%, n = vs .%, n = ,
χ = ., P = .) and in unfenced vs fenced fields
(.%, n = vs .%, n = , χ = ., P = .). The
number of fields where entry by hippopotamuses was de-
tected was significantly lower for fenced than unfenced
fields (.%, n = vs .%, n = , χ = ., P , .). FIG. 3 Mean number of flooded rice fields (with % confidence
In flooded fields we detected hippopotamuses intervals) in the study areas in Guinea-Bissau (Fig. ) where
during September−January (n = ), mostly during hippopotamuses were detected during various stages of crop
development.
October−December (.%). In rain-fed fields we detected
hippopotamuses in August and September (n = ). In all
areas studied the number of fields where hippopotamuses
number of cultivated flooded fields increased significantly
were detected was significantly higher at the end of the
during the study (. ha in , n = ; . ha in
rainy season and at the start of the dry season than at
, n = ; r = ., r = ., P = .) and consequently
other times (χ = ., P , .; Fig. ), and during the
rice production increased (from , kg in to ,
period of vegetative stem growth than during sowing and
kg in ). The mean productivity increased significantly
harvest (χ = ., P = .; Fig. ).
after the installation of the electric fencing (. vs .
kg ha−, n = ; Z = ., P = ., n = ).
Area and productivity of rice fields The area of rain-fed fields in Orango decreased (. ha
in , n = ; . ha in , n = ), although not sig-
The area of flooded fields was .−. ha in Orango and nificantly (r = ., r = −., P = .). The number of
.−. ha on the mainland. The total area and the families working in fenced fields in Orango increased
Oryx, 2017, 51(2), 222–229 © 2016 Fauna & Flora International doi:10.1017/S003060531500109X
Downloaded from https://www.cambridge.org/core. IP address: 46.4.80.155, on 23 Sep 2021 at 23:33:30, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms
. https://doi.org/10.1017/S003060531500109XPreventing crop raiding by hippopotamus 227
installed the hippopotamus passed between the two wires,
pushing one wire until the tension caused it to break, or
breaking the wire by standing on it.
Discussion
Our results indicate that the frequent access of hippopot-
amuses to flooded rice fields resulted in significant damage
to crops, confirming the information provided by farmers in
previous studies (Lopes, ; Campos et al., ) and as
occurred in other regions (Clarke, ; Mkanda, ;
Kendall, ). In our study area, as in other regions
(Verweij et al., ; Chansa et al., ), the dry and
PLATE 2 A hippopotamus Hippopotamus amphibius feeding in a humid savannah grasslands are the preferred feeding
flooded rice field in Carantaba, observed by local people. grounds of the hippopotamus, and are the habitat that
(Photograph by Tete Sambu, ) holds the greatest diversity and abundance of grass species.
In our study area up to species have been identified in the
diet of the hippopotamus (Duarte et al., ). Much of the
diversity and abundance of local grass species is maintained
in the flooded rice fields (Catarino et al., ), which could
explain why hippopotamuses are attracted to these areas.
Hippopotamuses frequently enter flooded fields when the
stem rice is in the vegetative growth phase, at the end of
the rainy season and the beginning of the dry season, and
also when the dry savannah grass begins to dry out and
humid savannah grasses and stem rice in flooded fields
are still green and growing (Catarino et al., ). The dry
savannah grasses are found in the plains and are rarely in-
PLATE 3 Camera trap images of a hippopotamus crossing an undated, whereas the humid or wet savannah are flooded
electric fence in a rice field in Acagume (Orango), in . during the wet season, with the dominant species being
Anadelphia afzeliana (Duarte et al., ). Thus, the
humid savannahs and the flooded rice fields established in
significantly (from in to in , r = ., r =
them constitute a critical dry-season feeding ground for
., P = .).
hippopotamuses, and could explain the high frequency of
hippopotamuses entering these rice fields.
Hippopotamus behaviour The lower frequency of hippopotamuses entering
rain-fed fields compared to flooded fields is probably a re-
Hippopotamuses entered the fields at night, except in one sult of rain-fed fields generally being located far from water-
case where an individual was observed feeding during the courses. In addition, in rain-fed fields vegetative stems grow
day in an unfenced field (Plate ). Although hippopot- earlier during the rainy season, when the greatest abundance
amuses were detected in fenced fields, in nine of these of pasture is available in the dry savannahs. Thus, rice-
the electric system was not operating because the surround- planting dates, which determine the duration of the
ing vegetation was in contact with the wire or the wire was cultivation in each season, could be a factor in determining
not connected to the energizer. After resetting the appropri- the extent of crop damage by hippopotamuses, and could be
ate operating conditions we detected no more entries into adjusted to minimize the amount of damage caused. In
these fields, although the hippopotamuses did make further flooded fields, as in rain-fed fields, the dates for sowing
attempts. Only in one field did an individual enter while the seeds could be brought forward by using short-cycle seeds,
electric fencing was operating properly, and this same indi- to match the period of vegetative stem growth to that of the
vidual (as indicated by the marks on their skin, Plate ), natural grasses in the hippopotamuses’ feeding grounds.
an adult male, entered the field .% of the days surveyed Electric fencing produced a negative reaction in hippo-
(n = ). The individual entered for the first time before the potamuses because they tended to touch the wire with
electric fence had been installed, and after installation en- their noses, a poorly insulated and highly innervated part
tered by walking below the wire. After a second wire was of the body (Eltringham, ). However, we observed one
Oryx, 2017, 51(2), 222–229 © 2016 Fauna & Flora International doi:10.1017/S003060531500109X
Downloaded from https://www.cambridge.org/core. IP address: 46.4.80.155, on 23 Sep 2021 at 23:33:30, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms
. https://doi.org/10.1017/S003060531500109X228 L. M. González et al.
individual that crossed the electric fence while it was oper- limited applicability in many countries (Lindsey et al.,
ating. It touched the wire with its neck, back or chest ). In our study there were no malfunctions of the electric
(Plate ), which are less sensitive areas than the nose, and equipment, and the few incidents detected were attributable
then moved swiftly, crossing before the electrical pulse to human factors and were easily resolved. The success of
was generated. We do not discard the possibility that this electric fencing as a deterrent was primarily a result of
individual may have been tolerant to the level of shock in- using a new energizer unit, which is portable, well suited
tensity. The decrease in detection of hippopotamuses in to the various enclosure sizes and moisture conditions in
fenced fields over the course of the study period may also the field, and its operation is simple and easily understood.
indicate that damage was caused by a few individuals, who Thus, based on our results we conclude that the electric fen-
learned to avoid the fields after the electric fences were in- cing system, if used properly, is potentially an efficient and
stalled. Hippopotamuses may also have detected the electric viable method of preventing the access of hippopotamuses
fence without actually touching it; as has been suggested for and other megaherbivores into crop fields. However, electric
domestic animals, they may have detected the odour, elec- fences should be designed to minimize the loss of wild ani-
tromagnetic field or ozone generated around the wires mals as a result of entanglement or electrocution (Lindsey
(McKillop et al., ). et al., ). As the components of electrified fencing are
A potential ecological disadvantage of fenced fields is valuable and vulnerable to theft, their use should be re-
that fencing may be regarded as an incentive to transform stricted to smaller and well-surveyed protected areas
humid savannahs to flooded rice fields, which could reduce where there are severe human−wildlife conflicts.
hippopotamuses’ access to dry-season grazing grounds. In
this context, and considering that the grazing requirement,
estimated in a subtropical ecosystem, is ha of grassland per Acknowledgements
individual (Chansa et al., ), the hippopotamus popula-
tion of Orango, estimated to be individuals (Silva, ), We thank the technicians of the Instituto da Biodiversidade
requires ha of grassland, which is less than the area of e das Áreas Protegidas of Guinea-Bissau (IBAP), in particu-
dry and humid savannahs available, estimated to be , ha lar the Director Alfredo Simão, and Justino Biai, Cristina
(Cuq et al., ). The hippopotamus population is probably Silva, Aissa Regalla, Antonio Da Silva, Domingozinho,
below its carrying capacity in Orango. Although hippopot- Fernando Biagi, Januario Gomes, Domingos Betunde and
amus populations are limited by food availability in the dry Cecilia Netambo. We are also grateful to the wardens of
season (Lewison, ; Harrison et al., ), in Orango the Orango National Park and Tarrafes do Rio Cacheu
savannahs are the most extensive habitat, occupying % of Natural Park for their invaluable help. We especially
the surface area (Cuq et al., ), and have increased not- thank Jose Eliseo Benante, Teté Sambú and Guerra
ably since the mid th century (Vasconcelos et al., ). Bidonga. We are grateful also to Pierre Campredon,
This could mitigate the effects of fencing in reducing hippo- Nelson Dias, John Sivhik and Kurt Verkauteren for provid-
potamuses’ access to flooded fields. However, we recom- ing technical assistance. Jean Paul Taris, Luc Hoffman,
mend an assessment of the impact of fencing flooded Ignacio Morillo, Mary Seck, Iris Cardiel, José Jiménez,
fields on the ecological requirements of hippopotamuses, es- Francisco Cantos, Miguel Angel Cedenilla, Sandra
pecially during the dry season. Agudín, Fernando Silvestre, Mercedes Muñoz and Cristina
In the two protected areas the wildlife authorities do- Martínez provided advice and logistical support throughout
nated the electric fencing to the farmers, who paid a small this study. We thank Rubén Moreno-Opo and Jaime Muñoz
amount annually for maintenance and installation. With for comments and advice. Financial support for this study
the fencing we observed that night watchmen were no long- was provided by MAVA Foundation, Fundación
er necessary to protect the crops. There was a notable in- Biodiversidad of Spain, O. A. Parques Nacionales,
crease in the number of active flooded rice fields, rice MAGRAMA and AECID Spain.
production and the number of families working in the fields.
For these reasons, in this case mitigation is more cost effect-
ive than compensation. In this context we recommend that References
further interviews are conducted with farmers to ascertain if A LV E S , J. & B A R R O S , A.E. () Estudo de incidência sócio-económica
the attitude of the local population towards hippopotamuses da criação do Parque Nacional no Grupo de Ilhas de Orango.
has improved following this study, and if the conflict has Gabinete de Planificação Costeira, IUCN, Bissau, Guinea-Bissau.
been mitigated. B I A I , J.C.M. () Análise das alterações das manchas de coberto
vegetal nos Parques de Cacheu e Orango (Guiné-Bissau). Centro
Electric fences have been demonstrated to be useful in
Nacional de Informação Geográfica, Lisbon, Portugal.
preventing crop raiding by megaherbivores in Africa. C A M P O S , A., M O N T E I R O , H., S O A R E S , J. & C AT R Y , P. () O
However, because of financial constraints, complex main- Hipopótamo no Parque Nacional de Orango. IUCN, Bissau,
tenance and the need for trained personnel they are of Guinea-Bissau.
Oryx, 2017, 51(2), 222–229 © 2016 Fauna & Flora International doi:10.1017/S003060531500109X
Downloaded from https://www.cambridge.org/core. IP address: 46.4.80.155, on 23 Sep 2021 at 23:33:30, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms
. https://doi.org/10.1017/S003060531500109XPreventing crop raiding by hippopotamus 229
C ATA R I N O , L., D U A R T E , M.C. & D I N I Z , M.A. () Aquatic and L I N D S E Y , P.A., M A S T E R S O N , C.L., B E C K , A.L. & R O M A Ñ AC H , S. ()
wetland plants in Guinea-Bissau: an overview. Systematics and Ecological, social and financial issues related to fencing as a
Geography of Plants, , –. conservation tool in Africa. In Fencing for Conservation: Restriction
C ATA R I N O , L., M A R T I N S , E.S., B A S T O , M.F.P. & D I N I Z , M.A. () of Evolutionary Potential or a Riposte to Threatening Processes (eds M.
An annotated checklist of the vascular flora of Guinea-Bissau (West J. Somers & M.W. Hayward), pp. –. Springer, New York, USA.
Africa). Blumea, , –. L O P E S , A.J. () Estudo da populaçao de hipopotamos no Parque
CCKP (C L I M AT E C H A N G E K N O W L E D G E P O R TA L ) () Http:// natural des tarrafes do Rio Cacheu e zones adjacentes e Suzana e
sdwebx.worldbank.org/climateportal [accessed January ]. Varela. IUCN, Bissau, Guinea-Bissau.
C H A N S A , W., S E N Z O T A , R., C H A B W E L A , H. & N Y I R E N D A , V. () M C K I L LO P , I.G., P E P P E R , H.W., B U T T , R. & P O O L E , D.W. ()
The influence of grass biomass production on hippopotamus Electric Fence Reference Manual. Research and Development
population density distribution along the Luangwa River in Zambia. Surveillance Report . Defra, London, UK.
Journal of Ecology and the Natural Environment, , –. M E D I N A , N. () O ecossistema orizícola na Guiné-Bissau: principais
C L A R K E , J.R. () The hippopotamus in Gambia, West Africa. constrangimentos à produção na zona I (regiões de Biombo, Cacheu e
Journal of Mammalogy, , –. Oio) e perspectivas. MSc thesis. Universidade Técnica de Lisboa,
C U Q , F., C A M P R E D O N , P., G I R A U D E T , J., G O U R M E LO N , F., Lisbon, Portugal.
P E N N O B E R G , D.A. & S I LVA , A. () Un Système d’Information M I C H E Z , A. () Etude de la population d’hippopotames
Géographique pour l’aide à la gestion intégrée de l’archipel des (Hippopotamus amphibius) de la rivière Mouena Mouele au Parc
Bijagos (Guinée-Bissau). Géosystèmes, Brest, France. National du Loango-Sud (Gabon). MSc thesis. Gembloux Agro-Bio
D U A R T E , M.C., C AT A R I N O , L. & R O M E I R A S , M.M. () Aspectos Tech, Université de Liège, Gembloux, Belgium.
fitogeográficos das gramíneas na Guiné-Bissau. Portugaliae Acta M K A N D A , F.X. () Conflicts between hippopotamus
Biologica, , –. (Hippopotamus amphibious (L.)) and man in Malawi. African
E LT R I N G H A M , S.K. () The Hippos. Academic Press, London, UK. Journal of Ecology, , –.
F U N G O , B. () A review crop raiding around protected areas: S I LVA , C. () Recenseamento annual da popolaçao de
nature, control and research gaps. Environmental Research Journal, , Hippopotamus amphibius no PNO e Ilha de Uno. IBAP/IUCN,
–. Bissau, Guinea-Bissau.
H A R R I S O N , M.E., K A L I N D E K A F E , M.P. & B A N D A , B. () The S I LVA , C. & M O N T E I R O , H. () Missao de avaliaçao do impacte de
ecology of the hippopotamus in Liwonde National Park, Malawi: hipopotamos nas bolanhas de Carantaba e Bissora. IBAP/IUCN,
implications for management. African Journal of Ecology, , – Bissau, Guinea-Bissau.
. S TAT S O F T () Statistica v. .. Http://www.statsoft.com [accessed
IBAP (I N S T I T U T O D A B I O D I V E R S I D A D E E D A S Á R E A S P R O T E G I D A S ) March ].
() Plano de Gestao do Parque Natural dos Tarrafes do Río V A S C O N C E LO S , M.J.P., B I A I , J.C.M., A R A Ú J O , A. & D I N I Z , M.A. ()
Cacheu. IBAP, Bissau, Guinea-Bissau. Land cover change in two protected areas of Guinea-Bissau (–
IBAP (I N S T I T U T O D A B I O D I V E R S I D A D E E D A S Á R E A S P R O T E G I D A S ) ). Applied Geography, , –.
() Estratégia Nacional para as Áreas Protegidas e a conservação V E R W E I J , R.J.T., V E R R E L S T , J., L OT H , P.E., H E I T K Ö N I G , I.M.A. &
da biodiversidade na Guiné-Bissau –. IBAP, Bissau, B R U N S T I N G , A.M.H. () Grazing lawns contribute to the
Guinea-Bissau. subsistence of mesoherbivores on dystrophic savannas. Oikos, ,
K E N D A L L , C.J. () The spatial and agricultural basis of crop raiding –.
by the Vulnerable common hippopotamus Hippopotamus W O O D R O F F E , R., T H I R G O O D , S. & R A B I N OW I T Z , A. (eds) ()
amphibius around Ruaha National Park, Tanzania. Oryx, , –. People and Wildlife: Conflict or Coexistence? Cambridge University
L E W I S O N , R. () Population responses to natural and human Press, Cambridge, UK.
mediated disturbances: assessing the vulnerability of the common
hippopotamus (Hippopotamus amphibius). African Journal of
Ecology, , –. Biographical sketches
L E W I S O N , R. & O L I V E R , W. () Hippopotamus amphibius. In IUCN
Red List of Threatened Species v. .. Http://www.iucnredlist.org L U I S M . G O N Z Á L E Z and F R A N C I S C O G . D . M O N T O T O conduct re-
[accessed July ]. search on threatened species, human−wildlife conflict and biodiversity
L E W I S O N , R.L. & C A R T E R , J. () Exploring behavior of an unusual conservation. T O M E M E R E C K , J U N I O R A L V E S and J O S É P E R E I R A
megaherbivore: a spatially explicit foraging model of the work on wildlife monitoring and sustainability projects for biodiversity
hippopotamus. Ecological Modelling, , –. conservation in Guinea-Bissau. P A B L O F E R N Á N D E Z D E L A R R I N O A ,
L I M O G E S , B. & R O B I L L A R D , M.J. () Proposition d’un plan A N A M A R O T O and N U R I A E L - K A D H I R work on threatened species
d’aménagement de la Réserve de la Biosphere de l’archipel des Bijagós. and on a variety of sustainability projects for biodiversity conservation
Vol. . Les espèces animales: distributions et recommandations. and livelihood improvement in African countries. L U I S B O L O N I O
CECI/IUCN/MDRA, Bissau, Guinea-Bissau. studies the ecology and conservation of threatened birds.
Oryx, 2017, 51(2), 222–229 © 2016 Fauna & Flora International doi:10.1017/S003060531500109X
Downloaded from https://www.cambridge.org/core. IP address: 46.4.80.155, on 23 Sep 2021 at 23:33:30, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms
. https://doi.org/10.1017/S003060531500109XYou can also read
