Status of Hirola in Ishaqbini Community Conservancy J. King, A. Wandera, M. I. Sheikh, Y. H. Muhumed & I. Craig May 216
SUMMARY Monitoring of Hirola in the Ishaqbini Community Conservancy has been carried out by Conservancy Rangers since 28 using a simple ranger-based monitoring system established by NRT, called the Wildlife-Conservancy Management Monitoring System (Wildlife-CoMMS). This report provides a summary of the data collected by rangers on the demography of Hirola inside and outside the predator proof sanctuary since the sanctuary was established in August 212. It also includes data from aerial surveys conducted by NRT in both the sanctuary and wider Conservancy providing population estimates of other key wildlife species. A summary of the status of Hirola populations in the sanctuary and Conservancy is given below. Sanctuary Population has doubled in just over 3 ½ years to approximately 1 individuals Average annual population growth 2% Breeding season pattern changed from seasonal peak associated with rains in October December, to births throughout the year Proportion of sightings of adult females to adult males has changed from 3.4:1 in the 1 st year to 1.8:1 in the 4 th year Conservancy Low sightings of calves (-6mth age group) in the wider Conservancy compared with sanctuary suggests possibly low birth rate and/or low calf survival Higher proportion of sightings of adults in Conservancy than in Sanctuary highlighting the low proportion of calves in this population Summary statistics for the Hirola population in the Sanctuary and Conservancy for period since the sanctuary was established. Summary statistics Sanctuary Conservancy August 212 April 216 Adult sightings 72% 85% Sub-Adult sighting 8% 7% Calf sighting (-6mth) 2% 8% Ratio of sightings Adult Female: Adult Male 2.6 : 1 2.3 : 1 Calf mortality rate 3% 44% * Average herd size 7.5 5.4 Maximum herd size 23 16 Estimated population Feb 216 97 63 Priority next steps for the Hirola recovery program in Ishaqbini include: 1. Expansion of the Sanctuary 2. Implement a Disease Surveillance and Livestock Health Program 3. Improved monitoring of Hirola outside the sanctuary by Ishaqbini rangers * Abdullahi H. Ali pers. comm. 1
1 Methods Monitoring of Hirola in the Ishaqbini Community Conservancy and Sanctuary is carried out by Conservancy Rangers as part of their routine patrols and integrated into NRT s ranger-based wildlife monitoring system Wildlife-CoMMS. Data is collected on paper datasheets and entered into the W- CoMMS database in situ which provides the Conservancy with the ability to immediately analyse the data and generate relevant reports. Four rangers are dedicated to monitoring within the sanctuary, gathering information on Hirola demography (new births, age and sex structure of herds), other wildlife sightings and wildlife mortality. Outside the sanctuary rangers gather similar information including illegal activities and human-wildlife conflict. However, the level of monitoring effort outside the Sanctuary has been much lower than inside. There are very few literate rangers who can gather data and changes in personnel have meant that data collection in the wider Conservancy has not been consistent (for the period between August 212 April 216 there were 87 records of Hirola with demographic data i.e. age and sex of individuals, compared with 177 records of Hirola demography in the sanctuary). The results on the demography of Hirola outside the Sanctuary therefore need to be viewed with caution. Two total aerial counts (using a Piper Super-Cub, 2-seater aircraft) combined with a ground count were carried out in November 214 and February 216 to estimate as accurately as possible the population of Hirola and other large mammals in the Sanctuary, and the wider Conservancy. Within the sanctuary the aerial survey used a 5m strip width; each Hirola herd observed by the ground teams were also verified by the aerial team and vice versa. Outside the sanctuary the aerial survey used a strip width of 1km, Hirola herds observed by ground teams within the Conservancy were also verified by the aerial team. Results from aerial and ground teams were mapped to compare and remove any duplicates from the final totals. 2 Status of Hirola in the Sanctuary Table 1: Summary of status of Hirola sanctuary population from August 212 to April 216: Estimated Founder population size Number of births Number of deaths Estimated sanctuary population size Population increase (%) 48 63 14 1 (97-13) 12 % 2% Av. Annual population increase % p.a. Population Size The population of Hirola in the sanctuary has grown from founder population of approximately 48 individuals in August 212 to approximately 1 individuals by the end of April 216, a doubling of the population in just over three and a half years. The total number of Hirola based on births and deaths recorded by Conservancy rangers was 97 at the end of April (Fig.1). Two aerial surveys have been carried out since the sanctuary was established, in November 214 and February 216. Population estimates based on the aerial surveys have consistently given a slightly higher figure (+8 and +6 individuals), suggesting that the actual population is between 97-13 individuals. The average annual growth rate since the sanctuary was established was 2% (range 17-24%). 2
Aug-12 Oct-12 Dec-12 Feb-13 Apr-13 Jun-13 Aug-13 Oct-13 Dec-13 Feb-14 Apr-14 Jun-14 Aug-14 Oct-14 Dec-14 Feb-15 Apr-15 Jun-15 Aug-15 Oct-15 Dec-15 Feb-16 Apr-16 Aug-12 Oct-12 Dec-12 Feb-13 Apr-13 Jun-13 Aug-13 Oct-13 Dec-13 Feb-14 Apr-14 Jun-14 Aug-14 Oct-14 Dec-14 Feb-15 Apr-15 Jun-15 Aug-15 Oct-15 Dec-15 Feb-16 Apr-16 12 1 8 6 4 2 48 Figure 1: Hirola sanctuary population size - based on reported births and deaths August 212 - April 216 97 popln size Aerial survey total Births and Deaths A total of 63 births and 14 deaths of hirola have been recorded by rangers since the sanctuary was established. A change in the pattern of births has occurred, from an initial obvious seasonality in the first two years with a major peak in October December during the rains (62-65% of calves born in these three months in 213 and 214), to a longer birthing season with births being recorded the whole year round (Fig. 2). In 215 births were recorded in all but one month (February), with 6-18% of calves born per month for the remaining months. It is likely that as a result of improved vegetation cover in the sanctuary, due to exclusion of livestock, the constant availability of water and food means that breeding is no longer seasonally restricted in the sanctuary population. This shift in breeding pattern has been observed in other antelope species in captivity whose birthing correlates with rainfall season in the wild 1. 9 8 7 6 5 4 3 2 1 - Figure 2: Hirola births and deaths in the Sanctuary August 212 - April 216 New births Deaths 1 Schuler P Y, Hammer C, Clauss M & S Hammer 29 Birth seasonality in captive bovides at Al Wabra Wildlife Preservation (AWWP), Quatar. Proc. Int. Conf. Dis. Zoo. Wild. Anim. 3
% sightings Two calves were reported to have died immediately after birth, this represents a 3% mortality of the -3mth age group, compared with 41-7% mortality of this age group in wild Hirola reported by Andanje 2, and 42% in zoo-born hirola 3. No calves in the 3-6mth age category were reported to have died. Six deaths were reported since the previous NRT report (which covered the period August 212 April 214): 2 were calves which died immediately after birth; 3 were adults presumed to have died from old age (worn horns and teeth), and one was a sub-adult female which died in the sanctuary fence reportedly trying to reach a herd that was on the other side of the fence. The sub-adult female death could be as a result of being pushed out of the herd. In natural conditions lone females pushed out of herds would come together to form a new herd, as the population grows in the sanctuary habitat and space for new herds may become restricted causing intra specific fighting between females (M. Fisher & C. Penny pers. comm.). Male-male fighting has been observed once and resulted in the death of 2 males in March 214. Social factors constraining population growth, such as intra-specific fighting, are being monitored as one of the indicators over-population in the sanctuary. Population Demography 8 7 6 5 4 Figure 3: % sightings of sex and age classes each year since the sanctuary was established 3 2 25 19 1 9 Yr1 Yr2 Yr3 Yr4 (7 mths) Adult Female Adult Male Total Adults Sub Adults Calves (-6mth) 73 46 The proportion of sightings of Hirola different ages and sexes is used as an indicator of the age and sex structure of the population. Over the three and a half years since the sanctuary was established there has been an increase in sightings of adult males (from 15 to 25%), and a decline in sightings of adult females (from 54 to 46%). Sightings of calves (-6mths), sub-adults and adults overall have remained relatively stable (Fig. 3). The founder population was skewed towards adult females which were the majority of individuals translocated into the Sanctuary. The ratio of sightings of Adult Females : Adult Males has declined from 3.4 : 1 in Year 1 to 1.8 : 1 in Year 4. In an unconfined situation young adult males would naturally disburse and be pushed out of the area by territorial males, this is obviously not possible in the fenced sanctuary. This needs to be closely monitored and if there are signs of aggressive male-male competition and declining rate of population growth it may be necessary to remove excess males from the Sanctuary into the surrounding Conservancy. 2 Andanje S A 22 Factors limiting the abundance and distribution of Hirola (Beatragus hunteri) in Kenya. PhD thesis: University of Newcastle Upon Tyne, UK. 3 Probert J & Andrews J 216 The past, present and future of Hirola in captivity. Unpublished report. 4
% sightings There are approximately 9 mixed herds in the sanctuary that are of relatively stable composition, although it appears that individuals join and leave the herds at times. Maximum herd size reported between May 214 to April 216 was 23 individuals. Average herd size in the sanctuary based on all sightings reported by rangers is 7.5 individuals. There are several bachelor male herds in the sanctuary ranging in size from 3 16 individuals at different times. 2 Status of Hirola in the Conservancy Population Demography The proportion of sightings of Hirola of different ages and sexes can be used as an indicator of the age and sex structure of the population. Sightings of Hirola outside the sanctuary (within the wider Conservancy) were analysed over the same period since the sanctuary was established (August 212 April 216). Overall the proportion of sightings of Adults in the Conservancy was 85%, compared with 72% in the Sanctuary, and sightings of calves (-6mths) was 8% compared to 2% in the Sanctuary (Fig. 4). Sightings of sub-adults were almost the same both inside and outside the sanctuary. 9 8 7 6 5 4 3 2 1 Figure 4: Proportion of hirola sightings of different sex and age classes inside the Sanctuary and Conservancy, Aug 212 - Apr 216 56 5 24 19 85 72 7 8 8 Adult Female Adult Male Total Adults Sub Adults Calves (- 6mth) 2 Conservancy Sanctuary These results support anecdotal observations that there are fewer calves born and fewer surviving in the Conservancy compared to the Sanctuary. Rangers have not gathered data specifically on calf mortality in the Conservancy, however, preliminary results from A. Hussein Ali s PhD study 4 show average of 44% calf mortality rate in the Conservancy. In 22, Andanje 2 reported calf mortality rates in the wild as between 41.2% and 69.8% which correlate with findings from recent research and would explain the low number of sightings of Hirola calves in the Conservancy. Predation on Hirola calves is likely to still be a constraint to population growth outside the Sanctuary. It is not clear whether low birth rate is also a factor affecting population growth in the wider Conservancy. 4 Abdullahi H. Ali pers comm. 216 5
The ratio of Adult Females to Adult Males sightings was 2.3 : 1 in the Conservancy over this timeperiod (compared with 2.6 : 1 for the Sanctuary). Average herd size in the Conservancy over the past two years was 5.4 individuals (compared to 7.5 in the Sanctuary) with a maximum herd size of 16 individuals reported on two occasions in May 215 and March 216. Only six Hirola carcasses were found by rangers outside the Sanctuary since August 212 April 216, 2 as a result of predation, one from poaching and three from unknown causes or old age. It is likely that rangers are not finding all the carcasses of Hirola that die, as mortality reporting is low compared with years prior to establishment of the Sanctuary. 3 Aerial Surveys & Other Wildlife NRT has carried out four aerial surveys in Ishaqbini Conservancy since we began working in the area; July 28, February 211, November 214 and February 216. The 211 survey was part of a wider ecosystem survey together with KWS, the others surveys have been specific to the sanctuary and Conservancy. Survey blocks that are counted (east of the Tana River) are shown in the adjacent map. Figure 5: Aerial survey blocks of Ishaqbini carried out by NRT Because these surveys have been carried out at different times of year, and season estimates of some species vary considerably; particularly Giraffe and Buffalo. In general wildlife moves in a north-west to south-east pattern depending on rainfall, with wildlife moving into the drier northwestern part of the Conservancy in the season, and to the south-east towards the edge of the Boni forest where there is permanent water and more pasture in the season. However, whilst numbers change most species are resident in the conservancy throughout the year. Lesser kudu, warthog, dik dik and gerenuk are abundant throughout the Conservancy and Sanctuary, however they are either relatively small, or cryptic and prefer bushy areas and therefore difficult to count accurately from the air. Estimates of these species are not given in the following graphs and tables as they are considered to be underestimates. Estimates for key species in February 216 in the Sanctuary and wider conservancy are shown in the table below. Of note is the herd of approximately 47 elephants in the Conservancy in 216; 6
prior to the Conservancy establishment, elephants were rarely seen in the area however there are now groups of elephants in the Conservancy throughout the year. A herd of 7 elephants broke through the Sanctuary fence in 214 and have remained in the sanctuary, with one female giving birth to a calf. The pair of oryx translocated into the sanctuary in August 212 has given birth to 2 calves. Similarly a pair of buffalo which broke through the fence have given birth to a calf. The Topi numbers have not increased, although there have been 4 births, one calf died immediately after birth and 3 adults died from hitting the fence. As wildlife numbers build up in the Sanctuary it may be necessary to remove some individuals, by dropping a section of fence and herding them out with a helicopter. The impact of giraffe on trees is being monitored. Browsing by giraffe is likely to open up areas of thick Acacia bush and encourage grass growth, which will be beneficial for Hirola. However if the impact on vegetation is considered too high and body condition of giraffe and other browsers declines, then some animals may be removed. Table 2: Aerial and ground survey population estimates of medium-large mammals in Ishaqbini sanctuary and Conservancy in February 216 February 216 Sanctuary Conservancy Hirola 97 63 Giraffe 147 42 Elephant 8 47 Topi 7 66 Buffalo 3 499 Oryx 4 - Zebra 31* 73 Eland - 7 Waterbuck - 27 Ostrich 2* 5* *underestimate 2 15 1 5 Figure 6: Hirola population estimates from aerial & ground surveys Ishaqbini Conservancy & Sanctuary 28 29 21 211 212 213 214 215 216 Conservancy Sanctuary Results from aerial surveys of Hirola (combined with ground counts in 211, 214 and 216) in the Sanctuary and wider Conservancy are shown below. Numbers of Hirola in the Conservancy have declined since 28, although some of these formed the sanctuary founder population of approximately 48 individuals in 212. Current estimates across the wider Conservancy are a less than half of the 28 estimate, however, when combined with the sanctuary population the overall number of Hirola has recovered to at least 16 individuals in Ishaqbini. Most Hirola in the Conservancy were found to the west of the Sanctuary in the core conservation area and Tana River Primate National Reserve (see maps Figure 11). Trends in other key species are largely affected by seasonal differences in survey time of year, with stable Giraffe and Zebra populations and possibly increasing Buffalo and Topi (see graphs Figures 7-1). Densities of giraffe and buffalo in Ishaqbini are some of the highest in the entire country. 7
Figure 7: Giraffe population estimates from aerial & ground surveys Ishaqbini Conservancy & Sanctuary Figure 8: Buffalo population estimates from aerial & ground surveys Ishaqbini Conservancy & Sanctuary 8 7 6 5 4 3 2 1 28 29 21 211 212 213 214 215 216 Conservancy Sanctuary 6 5 4 3 2 1 28 29 21 211 212 213 214 215 216 Conservancy Sanctuary Figure 9: Zebra population estimates from aerial & ground surveys Ishaqbini Conservancy & Sanctuary Figure 1: Topi population estimates from aerial & ground surveys Ishaqbini Conservancy & Sanctuary 12 1 8 6 4 2 28 29 21 211 212 213 214 215 216 Conservancy Sanctuary 8 7 6 5 4 3 2 1 28 29 21 211 212 213 214 215 216 Conservancy Sanctuary 8
Figure 11a: location of Hirola in the sanctuary and conservancy during aerial and ground counts in Feb 216 Figure 11b: Location of key species observed in the wider conservancy during aerial survey in Feb 216 (note distribution of these species inside the sanctuary is not shown) 9
Wildlife-CoMMS Results from ranger-based monitoring of wildlife (Wildlife-CoMMS), collected by rangers while on daily patrols both inside the sanctuary and the wider conservancy, show that sightings of most species, except elephant, are either stable or increasing over the past 3 years since the sanctuary was established. Giraffe were the most commonly reported species, followed by Plains zebra and Buffalo. Figure 12: Graphs of cumulative sightings of key species by rangers between 213 215 for the conservancy and sanctuary combined. Graphs show cumulative sightings for the sanctuary and conservancy combined. There were increased sightings of Buffalo, Giraffe, Ostrich and Plain s Zebra; stable sightings of Gerenuk, Lesser Kudu, Warterbuck and Topi and decreased sightings of Elephant. There were relatively few sightings of Lion, Cheetah, Wild Dog and Leopard (none inside the sanctuary which is predator proof), in these three years with no obvious trend. 1
4 Next Steps & Recommendations Sanctuary Expansion Hirola in the sanctuary are breeding well and the population is increasing at an average of 2% per year. It is likely that we will soon experience problems associated with over population and saturated carrying capacity of Hirola and other wildlife inside the sanctuary. NRT, through the Ishaqbini rangers are closely monitoring key indicators that will serve as triggers for management intervention (population growth, calf and adult mortality, body condition, social interactions and disease risk and habitat condition). NRT and Ishaqbini have reviewed different options for Phase 2 of the Hirola recovery program including: expansion of the sanctuary; establishment of a second sanctuary in Ishaqbini or elsewhere in the Hirola range; translocation of Hirola from the sanctuary to other sites within and outside the Hirola range; and free release into the wider conservancy. In discussion with the community the most preferred option is to expand the existing sanctuary to maximize on the existing infrastructure and management capacity already in place in Ishaqbini. Discussions have begun with the wider communities of both Ishaqbini and neighboring Ndera Community Conservancy on the feasibility of this expansion to determine community support for such a project and the implications for other wildlife and habitats. More detailed assessments will be carried out in the second half of 216 before submitting a formal proposal to KWS for review. Disease Surveillance & Livestock Health Mitigating disease risk is a priority for the sanctuary. In March 216 NRT together with the Ministry of Livestock and Pastoral Economy carried out a mass vaccination of livestock in the vicinity of the sanctuary. Over 16, head of livestock, including cattle, sheep and goats were vaccinated. Sheep were vaccinated against Peste Des Petit Ruminates (PPR) after a severe outbreak of this disease was reported. Goats were vaccinated against Contagious Caprine Pleuropneumonia (CCPP) and cattle against Black Quarter and Anthrax (BQ) or Contagious Bovine Pleuropneumonia (CBPP). The aim of the vaccination campaign was to both address the current disease outbreaks as well as reduce incidence of disease in livestock ulitising areas adjacent to the Sanctuary, thereby reducing the risk of transfer of these diseases to wildlife, particularly Hirola. This vaccination was the first step in a proposed Disease Surveillance and Livestock Health Program that NRT is planning to establish, in partnership with KWS, San Diego Zoo and the Ministry of Livestock and Pastoral Economy. Improved monitoring of Hirola outside the Sanctuary Analysis of the CoMMS data has highlighted the weakness in wildlife and Hirola demography monitoring outside the Sanctuary. The low level of literacy in rangers is a challenge and there is a need to recruit additional rangers in Ishaqbini who are literate and can carry out wildlife monitoring. NRT has recently recruited a Research & Monitoring Assistant for NRT-Coast who will oversee and support wildlife monitoring in Ishaqbini on a more regular basis. 11