Assess Potential Habitat of Extirpated
Formosan Sika Deer
(Cervus nippon taiouanus)
In Taiwan
Introduction
Traditional Economic Value for Sika Deer
The high economic value of Sika deer was a major factor contributing to the over-exploitation
and the extirpation of Sika Deer. This favorable market value for deer also influenced
by the Chinese diet culture. There is an ancient belief that a person will gain
the particular attributes and special nutritional properties by eating the part of
the animals with those specific remarkable attributes, especially in traditional
Chinese medicine. For example, the partially developed antlers of deer are considered
magical, because this is a fantastic vivid growing part of the bodies while observing
the dominant buck with a doe herd. The other useful products include bone marrow,
meat, penis, tendon, fat, blood, teeth, bile and skin. From a historic viewpoint,
this wide array of deer parts makes the deer the most economically valuable animal.
In addition, deer products are so important to have notable values as a cultural
symbol, because deer are considered good fortune, bringing a family health and long
life. Even in today's modern society in Taiwan and Hong Kong, the preference of
deer products crosses all social classes, irrespective of income capability, education
background and social status. This cultural tradition affects the market value for
deer, and still continues throughout geographical distribution of Chinese people
today.
Review of Formosan Sika Deer Status
The Formosan Sika Deer (Cervus nippon taiouanus) is a Taiwanese endemic subspecies,
and the only extirpated deer in Taiwan. They were once widespread and abundant over
the island of Taiwan. About 300-400 years ago it occurred in the plains and low hills
below 300 meters in altitude (Keno 1940, Su 1984), which the lowland area covers
about 40% of Taiwan. Deer have an important economic value and have been traditionally
utilized in many ways. In the early history of Taiwan, the migrant and indigenous
people hunted deer for food and by-products. In the late 1800's, as many as 50,000
Sika deerskins a year went to Japan (Kano 1940), and the deer pelt exports peaked
at 100,000 per year (Kuo 1994). After World War II, the native habitat was destroyed
by expanding agriculture and development. By 1969 the combination of severe exploitation
and habitat degradation led to the sika deer's extirpation in the wild (McCullough
1973), and the only remaining deer were in captivity (zoos or private gardens) for
exhibition and economic use.
The Origin of the Sika Deer Re-introduction Project
In 1974, IUCN listed the Formosan Sika Deer as one of the most threatened deer species
worldwide. As the result of its extinction in the wild from the entire island, the
Taiwan government and the public began to reflect on Taiwan's conservation policies
in the 1980's. For many decades, the government and people thought that industrial
and economic development had a supreme priority over environmental protection. When
the land was heavily industrialized and densely populated, a civic movement of conservation
gradually developed. The will and demand of civic society also influenced government.
The government finally passed its environmental policy plans for sustainable development
including ecological perspectives. In 1982, the Council of Agriculture in Taiwan
appointed reintroduction specialist group to integrate the Sika Deer Recovery Plan,
which was composed of professionals of ecology, behavior, vegetation history and
animal husbandry. Because the captive Sika deer in private husbandry field were
susceptible to hybridize with Japanese subspecies, the reintroduction specialist
group selected the strain population in Taipei City Zoo as the recovery source population.
After two year preliminary research in the zoo, they also chose Kenting National
Park as the recovery site to begin the re-introduction project of Sika deer.
Big Events (population census: m=male deer,
f=female deer number, table 1)
Jul 1984 & Mar 1986 - Selection of recovery core population from Taipei City
Zoo (Wang 1986).
Jul 1984 - The source deer population from Taipei City Zoo (5m : 17f) arrived at
the fenced Sheting Reintroduction Park (120 hectares) in Kenting National Park of
South Taiwan.
Jan 1987 - Survey of parasites and wildlife diseases in the reintroduction park (Shia
1988).
Dec 1988 - Six deer in source population (2m : 4f) were moved to food habit test
field to understand the impact toward local vegetation. The artificial supplement
was gradually stopped and Wang (1989) observed the adaptability of natural diet in
the wild.
Dec 1990 - The secondary source of recovery population from Tung-Hai University in
Taichung arrived in Area "Far Look" (10m : 8f) (Wang & Shie 1991).
Jan 1991 - Twenty-nine deer (19 radio-collared) were released into the fenced Area
I (4m : 6f), II (6m : 8f), and III (3m : 2f) ) (Wang et. al. 1992).
Mar 1993 - The gates between Area III and "Far Look" were open to regulate
the population structure and size (Wang et. al. 1994).
May 1993 - According the census by deer-driving count in Area I, Conservation managers
estimated the total population size was about 100 deer in Sheting Area I to III,
including Area "Far Look" (Wang et. al. 1994).
Jul 1993 - Assessed the recovery potential of Sika deer in Yang-Ming-Shan National
Park of North Taiwan (Wang & Cheng 1994).
Jan 1994 - Because the local population density of deer was as high as 3 deer per
hectare, managers released 10 deer (3m : 7f) out of the enclosure through the long
gateway between Area II & III into the wild (2m : 2f died in the same year) (Wang
et. al. 1994).
Apr 1995 - Release 10 deer (5m : 5f) by transporting (Wang et. al. 1996).
Jan 1997 - Release 30 deer (5m : 17f : 8 calves) by transporting. Estimated wild
population ranged from 70 to 80 (Wang et. al. 1998).
1999 - Updated population: inside the closure 300 deer; outside 150+ deer (COA 1999)
The Recent Status of the Re-Introduction Project
The Formosan Sika Deer recovery project began 15 years ago. Important factors to
evaluate the success of this single-species project relate to a self-sustainability,
potential habitat, genetic diversity, and public relationships. After releasing 10
deer into the wild in 1995, the recovery project of Formosan Sika deer entered the
most important stage. Within four reproductive seasons from 1995 till 1999, the deer
population outside the enclosure has increased rapidly to about 150 individuals.
As the administer, the Kenting National Park Headquarter not only needed to have
a basic project to monitor the population dynamics of the few radio-collared deer,
but also looked for researchers to study the surrounding potential habitat for suitability
for the re-introduced Sika deer. In this post-release stage, it is very important
to examine the up-to-date outcome continually, and assure deer population's self-sustainability.
Through 1999, this recovery project cost appropriately $6 million USD to establish
a self-sustainable and healthy population in the wild (COA 1999). Without any hunting
pressure, wild dogs and traps set (for boar and hare) were the primary sources for
the deer mortality (Wang & Cheng 1994). The deer population outside the enclosure
has been estimated to increase rapidly to 150+ individuals in 1999. The browsing
effect gradually included soil erosion, degradation of vegetation succession, changes
in forest composition and abundance, and the relative avian biodiversity changes.
In this paper, I integrate the limited recent knowledge of Sika deer, and follow
known ecological and social criteria to assess the potential habitat of recovered
Sika deer with Geographical Information System (GIS) in Taiwan. I also address the
conservation issues in both biological and sociological perspectives, and apply the
recent ecological and land use knowledge to develop suggestions and strategies to
sustain Sika deer and human communities. Below are 5 parts to analyze the potential
habitat and the future of Formosan Sika Deer in a human-dominated ecosystem:
Potential Habitat Estimation
Part A. Lowland (0-300m elevation)
Part B. Suitable Vegetation (Type I, II, III)
Part C. Lowest Category of Human Density (<270 people /Km2)
Part D. Other Conservation Concern: Poaching, Public Awareness...
Part E. Three Accessible Areas for Deer Recovery in the Future
Part A.
Lowland (0-300m elevation)
According to the historic records and the previous distribution in Japanese colony period, the habitat of Formosan Sika Deer was limited in the lowland plains and slow hill up to 300 meters in elevation (Kano 1940, Su 1985), including plains and open forests (Cowan & Holbway 1978). The middle to high altitude mountainous area is not potential habitat for Sika deer's survival. Finally, I select the lowland part (0-300 meters) of Taiwan as the potential habitat in a broad definition.
However, in the post-modern industrial period in Taiwan, most low-altitude area has
been developed as farmland, urban development, and industrial parks. Even though
Taiwan government adopts the similar protected area (PA) design as North America
and manages a number of preserved areas, it is still too late to protect the native
lowland forests. There is nearly 10 percent of Taiwan's land area in a multi-tiered
conservation system, including 6 national parks, 18 nature preserves, 20 nature reserves,
and 3 wildlife sanctuaries. Only 6% of PA area established in the crowded lowland
Taiwan below this historic distribution boundary of 300 meters of altitude for Sika
deer (only Kenting NP and other small reserved areas).
Part B
Vegetation as Food Supply and Shelter
Assess the Potential Habitat from Vegetation Viewpoint
From my observation between 1993 and 1994, Sika Deer adopted a more flexible strategy
to browse the forage plants in different height and maintain a dynamic relationship
with vegetation community (Hu et. al. 1994). The behavior of this locally largest
herbivore also shaped the microhabitats for other biomes and influenced the function
and structure of ecosystem. Because vegetation to Sika deer plays roles as food plant
and habitat, Sika deer feeded a widespread and exotic legume (a1, Leucaena glauca
(L.) Benth.) as much as 35% of intake time. Besides, Sika deer also kept a wide diversity
for 60% diet from 15 native species. Su (1985) reviewed the literatures about Sika
deer distribution and surveyed the historic habitat. The natural vegetation in Sika
deer habitat includes:
Type I: Tropical evergreen and broadleaf forest - Ficus / Machilus Type
The dominant canopy species are Ficus and Machilus as shelter trees. In the understory,
there is abundant ground layer to support diverse food source. This vegetation zone
most ranges in the middle slope and valley in the slow hill. Kenting National Park
and the whole neighboring Hengchun peninsula also locate within this area (fig 1).
Mulberry a4 (Broussonetia papyrifera (L.) L'Herit. ex Vent.) is the representative
tree as second-best nutritive choice.
Type II: Semi-deciduous mixed forest in lowland
This vegetation community includes plenty of evergreen Ficus, and a number of mixed
deciduous trees. It used to occur in plain, slow hill, and dry slope, which associated
with grassland. Because of economic and agricultural development, this habitat was
almost gone by 1970's. People changed the land use of this lowland to several artificial
plantations, such as bamboo, lowland orchard, and cropland with rice, tea (in the
north Taiwan) and sugarcane (in the middle and south Taiwan). Grass f1 (Miscanthus
floridulus (Labill.) Warb. ex Schum. & Laut. ) and mulberry a4 (Broussonetia
papyrifera (L.) L'Herit. ex Vent.) are common representative species as in Kenting.
Type III: Acacia confusa plantation and lowland secondary forest
The third important vegetation is Acacia (tree a33). Due to its fast-growing and
good-generating characteristics, humans planted this native tree as a fuel wood by
1970's and it replaced most vegetation in lowland and slow hill, after the logging
of native mixed forest (type I & II) (fig 1). In Kenting, even though in the
understory of Acacia, there are few ground plants germinating due to the toxins in
seed and leaves toward the other plants. Deer still seem to take advantage of Acacia
as shelter, and browse the neighborhood of the mosaic vegetation communities.
In Kenting, these three vegetation communities existed and used by deer. I observed
these native vegetation communities supported as much as 60% of deer diet in 1993-4,
and the other diet was from the exotic legume a1 (Leucaena glauca). This exotic legume
also invaded into the other possible habitat of Sika deer (vegetation type I, II,
III) (Su 1984). Based on the similar natural environment with Kenting, it is safe
to say food supply and shelter selection should not be a serious problem for Sika
deer recovery in the other possible vegetation.
Part C
Lowest Category of Human Density (<270 people /Km2)
All these above potential habitat (Lowlands with suitable vegetation) are
also impacted by the urban sprawl issue and crowded human population. Human population
density might be a good index to estimate where deer can recover. For example, In
the heavy human-populated area of lowland Taiwan, there was much road density and
human activities impacting the recovery deer population. The previous vegetation
which supported Sika deer 300 years ago had totally converted to heavy-cultivated
farmland (rice, tea and sugarcane) with rare fragmented forests (most of them were
secondary). Kenting National Park is located in the lowest category of human density
area (<270 people per square kilometer), which we think is the minimum base line
to recover Sika Deer. The deer might disperse to other crowded human populated area,
but in the beginning stage to establish a pioneer population , I would consider the
lowest human populated area as the most possible area to establish a self-sustainable
deer population.
Part D.
Other Conservation Concern:
Poaching
Hunting is illegal after Taiwanese government banned gun holdings and any
kind of wildlife hunting in 1976. In Kenting, there were still several cases for
boar or hare hunting around the Kenting National Park. Because of the frequency and
trap size/method, my estimation of potential habitat of recovered Sika deer assumes
there is not severe problem for poaching.
Human-Deer Conflicts: Public Relationship and Natural
Resource Community
Ecosystem management integrates knowledge of ecological relationships within a socio-political
value framework (Easter-Pilcher 1996). But in the beginning, the whole re-introduction
project was mostly centered on a self-sustainable deer population in a single-species
scale. The project ignored the socio-economically acceptability and the social changes
in rural communities. In the preliminary interviews (1996), most residents refused
to support the deer re-introduction because they were dissatisfied with the management
of Kenting National Park in several regulations of landuse and economic development.
The human-park or human-deer conflicts also resulted from the low degree of public-involvement
in the decision-making process, and the residents didn't realize the benefits from
the re-introduction project. There is an urgent need for this social debate to continually
monitor the restoration program in a human dimension sense, which allows all of the
stakeholders to keep learning, building their own experiences, and adjusting their
strategies to achieve the goals of the restoration as efficiently as possible.
Management effectiveness should be considered with resident attitudes and reactions,
either in behavior or perception. A self-evaluated, qualitative survey in a local
community scale is needed. It can be done mainly by interviewing the local opinion-leaders
and county institutions. Study factors will be various types of recreational, environmental,
economic benefits and problems, which the eco-restoration either directly provided
or caused. The research will provide a better understanding toward recovery project
in the rural communities near the PA Complex in South Taiwan. This attitudinal survey
can effectively offer guidance for further management adjustment, as well as provide
baseline data to assess eco-restoration policies (Scott et al. 1996). While working
with the local people and economic-politic organizations who face the changes from
eco-restoration, this advanced understanding in human dimension will greatly improve
the Sika deer recovery project, and enhance the participation of local people as
stewards. The ultimate goal of this eco-recovery project will be directed to look
forward upon the total ecosystem management with a view of broad human-environment
sense.
Human-Dominated Ecosystem Management
The conservation plan with an ecosystem point of view will focus on landscape and
ecological level, which emphasizes the function and structure of diverse ecosystems.
To human society, the health of ecosystems will maintain the necessary and treasured
service, such as clean water, fresh air and desirable living environment. In the
ecosystem management project, Sika deer are treated as a symbol to rebuild several
lost components in landscape. Functionally speaking, to maintain a successfully self-sustainable
deer population, human society has to make a mass decision to restore the reclamation
with proper and required vegetation communities. The diverse vegetation will provide
the habitats and shelters for wildlife like Sika Deer, and that restored environment
also work for human residents. This expensive recovery project of Sika Deer symbolizes
the contemporary conservation effort in Taiwan, especially the relative biodiversity
for Sika deer's survival and the whole environment are highly endangered today. It
has been identified that the potential habitat of Sika Deer is at severe risk, such
as wet and seasonally dry lowland deciduous broad-leaved forests. Strong habitat
loss and fragmentation in Taiwan are due to the conflicting utilities with human
economic development in the plains and basins. However the government and local non-government
organization (NGO) still work on the conservation of ecosystem and biodiversity.
We should seek any chance of the win-win situation of sustainable development, and
put the tax money on the ecosystem conservation with both economic efficiency and
environmental preservation in the future. Sika Deer will become a working goal and
a live symbol as an umbrella species, which endangered key species need a recovered
environment to coexist with the reflecting human society in the future.
Part E.
Three Accessible Area for Deer Recovery in the Future
I overlapped the GIS-based map with lowland, suitable vegetation type, and lowest
human density. We can identify 5 potential habitat for further dispersal of Sika
deer (fig 2).
1. Hengchun peninsula (fig 4):
Recently, the range of recovery project only limited in Kenting National Park. On
a fine scale, the Sheting re-introduction park (120 hectares) was almost overabundant
by the deer population growth. After the release in 1995, deer could expand their
range to disperse outward in 17,731-hectare Kenting National Park. On a broad scale,
we can treat the Heng-chun, including the Kenting National Park, as the area of natural
dispersal in the future. There is no need for transportation to move the recovery
population in this area.
2. The slow hill in Kaohsiung county (fig 3):
Relocation is needed for deer to occupy this area. This is the secondary ideal choice
next to the Hengchun peninsula. The area size is 2.5 times than Hengchun peninsula.
But the issue is there is no large protected area here. Conservation managers need
to deal with the possibility of local protected policy to recover the Sika deer.
3. Long Valley in Hualian-Taitung (fig 3):
Transportation is needed in this area. This location is also where the last deer
hunt recorded in 1969 (McCullough 1974). Due to the barrier of Central Mountain Ridge,
the Long Valley and the whole East Taiwan are still in low density of human population.
Relatively there are more wilderness keeping and fewer road impacts there. The possible
issue is the shape of feasible lowland habitat is long and narrow. Conservation managers
have to concern the population fragmentation and the relative difficulty of population
exchange for deer recovery.
Conclusion : The Future of Sika Deer
Three to four hundred years ago, the landscape in subsistence farming days was diverse,
with cultivated land mixed with land that could not be cultivated because it was
too wet, steep or rocky, and land that was devoted to pasture or wood production.
This mix of landscape elements provided potential habitat for great biodiversity.
But because of unregulated human over-exploitation, the species favored for food
or other use were often absent from extensive human habituated regions. The pattern
of landscape in the industrialized nations has changed from an earlier ecologically
diverse situation to an ecologically homogeneous current situation (Lal 1991).
Huge area of forest and small subsistence farms was replaced by larger scale of commercial
use and urban residence. This leads to that the diverse habitats characteristic of
woodland, wetlands, rocky areas, small fields with weedy, shrubby borders--were,
with the aid of powerful machines, transformed into large leveled, drained fields
growing single crops or becoming an intensively-populated area. In addition, the
industrial waste and by-product, and the agricultural chemicals used for fertilizer,
weed control, and insect control had unintended consequences in polluting streams
and poisoning food chains in ecosystem (Rowe et al. 1992). Finally the practices
of conservation plan in Taiwan need to make a big difference for these environmental
issues.
The eco-recovery of Sika Deer is a point to start. To protect the landscapes and
improve the environmental benefits for both human and wildlife, the modern society
is responsible for recognizing and rebuilding the balanced relationship interacting
between man and land. The natural biotic life styles and human economic activities
co-exist for a long time in human history. When we review this historic viewpoint,
it is the urgent mission for us to adjust our mixed cultural/natural landscapes and
ecosystems to function as well as before.
References
Council of Agriculture in Taiwan. 1999. The recovery result and expectation of Formosan
Sika Deer. Taipei City Zoo. Pp.1-23.
Cowan, I. M. & C. W. Holbway. 1978. Conservation status of the threatened deer
of the world in IUCN Threatened Deer.11p.
Easter-Pilcher, A. 1996. Implementing the endangered species act. Bioscience 46(5):355-363.
Ewel, J.J., Mazzarino M.J., & Berish C.W. 1991. Tropical soil fertility changes
under monocultures and successional communities of different structure. Ecol Applic
1: 289 302.
Feldhamer, G.A. 1980. Cervus nippon. Mammalian species. No.128, 7p.
Hu, C.H. & Y.Wang. 1994. A Preliminary Study of Food Habit of Formosan Sika Deer
( Cervus nippon taiouanus ). Biological Bulletin of National Taiwan Normal University
29(1):11-20.
Hu, C.H. G.J. Chen & Y. Wang. 1994. Seasonal Foraging Behavior of Formosan Sika
Deer ( Cervus nippon taiouanus ). Biological Bulletin of National Taiwan Normal University
29(1):21-26.
Hubbell, S.P. 1979. Tree dispersion, abundance and diversity in a tropical dry forest.
Science 203:1299-1309.
Kano, T. 1940. Zoogregraphical status of Tsugitaka Mountain of Taiwan Shibusawa.
Inst. Ethnogr. Res., Tokyo. 145p.
Kuo, Kuo-wei. 1994. The study of field behavior and habitat use of Formosan Sika
Deer (Cervus nippon taiouanus). M.S. thesis. National Taiwan Normal University,
Taipei, Taiwan.
McCullough, D. R. 1974. Status of larger mammals in Taiwan. Tourism Bureau, Taipei,
Taiwan, R. O. C. 35p.
Nowak, R.M. 1991. Walker's Mammals of the World. 5th Eds. Volume II. Johns Hopkins
Univ. Press. Baltimore and London. 1379p.
Noss, R., M. O'Connel, & D. Murphy. 1997. The science of conservation planning.
Island Press.
Lal, R. 1991. Myths and scientific realities of agroforestry as a strategy for sustainable
management for soils in the tropics. Adv in Soil Science 15:91-137.
Rowe, R, N. Sharma, & J. Browder. 1992. Deforestation: Problems, Causes, and
Concerns. Pp. 33- 45 In: Managing the World's Forests (ed N Sharma), Kendall/Hunt
Publishing.
Scott, T., M. Tear, & L. S. Mills. 1995. Socio-economics and the recovery of
endangered species: biological assessment in a political world. Conservation Biology
9:218-220.
Su, H.J. 1984. Studies on the climate and vegetation types of the natural forests
in Taiwan (I): analysis of the variations in the climatic factors. Quarterly Journal
of Chinese Forestry 17(3):1-14.
Taber, R.D. 1993. The mammals of Taiwan: Am introduction to their biology and conservation.
Pacific Cultural foundation. Taipei, Taiwan.
Wang, Y. 1985. The behavior of Formosan Sika Deer. Conservation report, no.18. Kenting
National Park. Pp.102-179.
Wang, Y. & S.S. Jan. 1987. The behavior of Formosan Sika Deer. Conservation report,
no.38. Kenting National Park. Pp.63.
Wang, Y., H.K. Wang & T.J. Shia. 1989. The behavior of Formosan Sika Deer. Conservation
report, no.561. Kenting National Park. Pp.1-41.
Wang, Y., H.S. Chen, S.J. Wu & M.I. Su. 1992. The behavior and habitat of Formosan
Sika Deer. Conservation report, no.78. Kenting National Park. Pp.41.
Wang, Y., G.W. Kuo & M.Y. Yen. 1993. The native habitat survey and release accessibility
estimation of Formosan Sika Deer. Conservation report, no.88. Kenting National Park.
Pp.60.
Wang, Y, K.W. Kuo, C.H. Hu & M. T. Chen. 1994. The tracking of released Formosan
Sika Deer. Conservation report, no.91. Kenting National Park. Pp.83.
Wang, Y., S.C. Chen, G.S. Shung, J.T. Lin, & S.F. Liao. 1996. The ecological
study of released Formosan Sika Deer. Conservation report, no.18. Kenting National
Park. Pp.102-179.
Wang, Y., S.C. Chen, J.T. Lin, S.S. Jan, & J.J. Cheng. 1997. The population monitor
and ecological impact of released Formosan Sika Deer. Conservation report, no.98.
Kenting National Park. Pp.45.
Wang, Y.,, S.S. Jan, S.C. Chen & F.H. Cheng. 1998. The population monitor and
ecological impact of released Formosan Sika Deer - GIS system application. Conservation
report, no.100. Kenting National Park. Pp.65.
Table 1. Population Life Table Analysis for Sika Deer in Kenting, Taiwan
Fundamental Setting:
1. f=female deer; m=male deer
2. calf needs about 1.5 years to reach sexual maturity
3. calf is born by July every year
4. the life span for Formosan Sika Deer is about 10-15 years.
5. In Sheting, Area O (field station), I, II, III, VI, V (Far Look) , and VI (ex-vegetation
control area) are available to recover Sika Deer.
Inside the closure:
A. Area O, I, II, III, VI and VI
Date m-adult f-adult m-calf f-calf total remark
Jan 1991 13 16 29
Jul 1991 13 16 8 8 45 Assume sex ratio is close to 1.
Jul 1992 21 (=13+8) 24 (=16+8) 8 8 61 Calves are from 16 f-adult.
Jul 1993 29 (=21+8) 32 (=24+8) 12 12 85 Calves are from 24 f-adult.
Jul 1994 41 44 16 16 117
B. Area V (Far Look)
Date m-adult f-adult m-calf f-calf total remark
Jan 1991 10 8 18
Jul 1991 10 8 4 4 26
Jul 1992 14 12 4 4 34
Jul 1993 18 16 6 6 46
Jul 1994 24 22 8 8 62
C. True Deer Census
May 1993 O (30), I(15), III+IV(19), VI(19) => total = 97
In Area VI: Dec 1988 2m+4f (6) --> 5 yr / 4 reproductive seasons --> May 1993
7m+8f+4calves (19)
In Area I: Jan 1991 4m+6f (10) --> 5 yr / 4 reproductive seasons --> April
1996 (40)
Outside the closure:
Date m-adult f-adult m-calf f-calf total remark
Jan 1994 3 7 10
Jul 1994 1 (=3-2) 5 (=7-2) 2 3 11 2f+2m died after release
Jul 1995 3 8 2 3 16
( additive herd 5 5 2 3 April 1995: release 5f+5m by transportation)
Dec 1995 8 13 4 6 31
Jul 1996 12 19 6 7
Jan 1997 18 26 na na
( additive herd 5 17 4 4 release 5f+17f+8c) population est = 80
Jul1997 23 43 17 17 (=13+4)
Jul 1998 40 60 21 22
Jul 1999 61 82 30 30 203 population est = 150+