The currently accepted nomenclature and taxonomy of Giraffe places the nine different types into subspecies categories. Some authorities have suggested that Thornicroft’s Giraffe should be elevated into their own species, G. thornicrofti (Groves and Grubb 2011), while other scientists have concluded that they should be subsumed into the proposed species, G. tippelskirchi (Fennessy et al. 2016). The conflicting interpretations of Giraffe taxonomy have led to the proposal that a thorough scientific evaluation of the evidence be initiated to assess how many species of Giraffe exist (Bercovitch et al. 2017).

Thornicroft’s Giraffe is an isolated population that survives only in the Luangwa Valley, eastern Zambia. Their restricted distribution coincides with a limited population size. In the 1960s, their numbers were estimated at around 300 to 500 individuals and current estimates place their numbers at approximately 600 Giraffe, of which an estimated 420 are mature individuals. The current population seems to be stable. Given their restricted distribution to a single location, the limited number of mature individuals, their relatively slow reproductive rate combined with high neonatal mortality rate, and their small population size, this subspecies of Giraffe is listed as Vulnerable under criterion D1.

Thornicroft’s Giraffe are restricted in range to the Luangwa Valley, eastern Zambia (Berry and Bercovitch 2017a). In 1938, their core habitat was designated a protected zone with the establishment of South Luangwa and North Luangwa Game Reserves. In 1972, both areas became National Parks and are part of the Greater Luangwa Ecosystem that includes two other National Parks (Luambe, Lukusuzi) and five Game Management Areas (GMAs: Munyamadzi, Lumimba, Lupande, Musalangu, Sandwe) (Simukonda 2012).

The closest natural Giraffe population to the Thornicroft’s Giraffe is the Masai Giraffe (G. c. tippelskirchi) living in southern Tanzania (Berry 1973, Berry and Bercovitch 2017a), at least 500-600 km to the north. The Luangwa Valley is traversed along the north/south axis by the Luangwa River, a meandering waterway characterised by several oxbow curves and lagoons and bracketed on the western side by the Muchinga Escarpment. The northern limits of the Thornicroft’s Giraffe are unclear, but their range extends to the region near the confluence of the Chibembe and Luangwa Rivers (ca. 12°50’S). Similarly, the southern limits are unknown, but probably extend to the confluence of the Msanzara and Luangwa Rivers (ca. 13°45’S). Giraffe range primarily along the Luangwa River and its tributaries, most often observed within 3 km of a river, although sometimes sighted up to 7 km distant (Berry 1978). Areas further from the riverfront tend not to be suitable Giraffe habitat, quite possibly because their major dietary items are not found in the miombo woodlands further away from the Luangwa River. Giraffe have rarely, but occasionally, been noted outside the area described above.

Although Thornicroft’s Giraffe range outside of South Luangwa National Park (SLNP), their stronghold is in the NP and the adjacent Lupande GMA. Those two areas accounted for 75% of sightings during one aerial survey (Simukonda 2012) and 73% of sightings during a second aerial survey (DNPW 2016). The entire SLNP covers 9,050 km², but the Giraffe do not live throughout SLNP.

Thornicroft’s Giraffe range from the confluence of the Chibembe and Luangwa Rivers to the confluence of the Msanzara and Luangwa Rivers, approximately 250 km, and rarely range beyond 3 km from the Luangwa River or its tributaries (Berry 1978). Giraffe do not occupy the entire area, but range in discrete pockets along the riverine environment and adjacent areas.

Historical Records:
Thornicroft’s Giraffe was initially described by Lyddeker (1911). In the early 1900s the population was estimated to number only 30-70 animals, mostly ranging on the east bank of the Luangwa River in small herds, but the methods used to derive these estimates are unknown and most likely involved the impressions of the early British administrators (Berry 1973). However, the counts indicate that the Giraffe were either few and/or that sightings were uncommon. One report in the 1920s of over 500 Giraffe appears to be inaccurate, based upon subsequent information (Berry 1973). Darling (1960) estimated 200-250 Giraffes along the east bank of the Luangwa River from about 130 to 140 S, and a few “vagrants” on the west bank. By the end of the 1960s, when people began to compile more accurate records of Giraffe observations, the number of Thornicroft’s Giraffe was estimated at between 150 and 300 individuals, with their range expanding in both northerly and southerly directions (Berry 1973). Berry (1973) noted that a few Giraffe were present on the west bank, but most of the population lived on the east bank. He also noted that the greatest north-south distance between sightings of individual Thornicroft’s Giraffe was between 110°50’S and 140°18’S, but that these sightings were either lone bulls or small herds. In 1969, Berry (1973) estimated a population size of 270-300, with Dagg and Foster (1982) concurring that the maximum population size was approximately 300 individuals.

Berry and Bercovitch (2017a) compiled Giraffe census counts from 1973 to 2003. All counts were obtained either on foot or from a vehicle, so the methods were consistent across years. Based upon the number counted, they estimated approximately 0.51 Giraffes/km surveyed. Given the range of the Thornicroft’s Giraffe, they concluded that approximately 500 to 600 Giraffes have been present in the Luangwa Valley in the 30-year period from 1973 to 2003. In 2013, another survey was conducted that counted Giraffes using the same methods (see below: Berry and Bercovitch 2017a).

Current Records: Aerial Survey
Two recent independent aerial surveys of Zambian wildlife have included population estimates of Giraffes. These estimates from both reports are provided here but also suggest a caveat. Two studies of Giraffes in Tanzania (Caro 2011, Lee and Bond 2016) have documented that when aerial and ground surveys of Giraffe are compared, the former underestimate the actual population size of Giraffes.

One aerial survey was undertaken of the Luangwa Valley Ecosystem during the wet season in 2011 to establish the status of elephants and other large herbivores resident in the area (Simukonda 2012). The survey was conducted over an 18-day period in May 2011, covering an area of 19,995 km² with an overall sampling intensity of 11%. The observers counted 44 Giraffes during the aerial survey and estimated a population size of 407 individuals (95% CI 121-647). Giraffe were observed in four areas (SLNP; Munyamadzi, Lupande, and Sandwe Game Management areas). The survey of these four areas encompassed 1,296 km², yielding a density of 0.03 Giraffe per km².

The second aerial survey was conducted in the dry season of 2015 (DPNW 2016). In September 2015, an area of 32,819 km² of the Luangwa Ecosystem was subject to aerial survey transects with an average survey intensity of 5.6%. The observers counted 11 Giraffe in the Luangwa ecosystem and estimated that 99 Giraffe live in the area (95% CI = 30 to 170), with 72 resident in SLNP. They concluded that the SLNP Giraffe population has crashed by 61% since 2002. However, the report also notes that the estimated population sizes of many of the large herbivores was probably underestimated, and we concur in this assessment for these key reasons: (1) the lowest number of Thornicroft's Giraffe in the population estimate (n = 30) is below the actual number observed on a single day in 2013 in a small section of SLNP (n = 40; Berry and Bercovitch 2017a), (2) the greatest number estimated (n = 170) is lower than the minimum number established (n = 423) using photographic ‘capture/recapture’ data (see below), and (3) the conclusion of a decline in population size was based upon an assumption that differences across years would reflect linear patterns. Whereas a linear trendline can be drawn that shows a decline in population size, an independent statistical analysis of the data revealed no increase or decrease, but stability (rs = 0.8, N = 4, p = 0.20). Hence, we omit the findings and interpretations from this report in this Red List Assessment of Thornicroft's Giraffes, due to the likely underestimation of population size and lack of clarity regarding population trends.

Current Records: Photographic “Capture/Recapture” Survey
Between March and October 2009, Giraffe were opportunistically photographed when encountered in the Luangwa Valley for purposes of conducting a photographic ‘capture/recapture’ study based upon individual coat pelage differences. Giraffes were identified using Wild-ID software (http://www.dartmouth.edu/~envs/faculty/bolger.html) (Halloran et al. 2015). Additional photographs collected since that time, and subject to the same software identification process, have resulted in a current estimate of a minimum of 423 Thornicroft’s Giraffe residing in the 2,775 km² survey area, or a density of 0.15 Giraffe/km², and an estimated population of 600 individuals (Becker, pers. comm., 2018).

Current Records: Giraffe Counting Survey
In 2013, a systematic count of Giraffe using direct ground observations was conducted in the SLNP to estimate Giraffe population size. The surveys consisted of two independent road counts that recorded herd size, composition, and, when possible, individual identity. Neither road survey adopted DISTANCE sampling because the limited sample sizes and environmental conditions precluded establishing a reliable detection probability (Caro 2011).

The first survey included six days of counting Giraffes in September 2013 that covered 67.9 km (Berry and Bercovitch 2017a). During the survey, the density of Giraffe ranged from 0.38/km to 0.53/km, with an average of 0.44/km. Giraffe were encountered in discrete areas rather than sighted all along the survey area. Given a Giraffe density of approximately 0.44/km along the Luangwa River, an approximate length of 250 km for the Luangwa River between the confluence with the Chibembe River and the confluence with the Msanzara River, and that Giraffe are rarely observed more than 3 km from a river (Berry 1978), then an estimated maximum of 660 Thornicroft’s Giraffe live in the Luangwa River Valley.

The second survey included collection of data over a 64-day period (4 September to 7 November 2013) that covered an average of 30 km/day. During this survey an average of 14.8 Giraffes were counted each morning and the density of Thornicroft’s Giraffe was 0.49 Giraffe/km driven. Following the same assumptions as in the above paragraph, the second survey produced an estimated maximum of 735 Giraffe in the Luangwa River Valley.

Conclusions:
Despite the differences in approach, all the reliable independent methods for estimating the current Thornicroft’s Giraffe population size converge on similar values. The lowest estimate was 121 Giraffe, the highest estimate was 735 Giraffe, and the surveys concur in suggesting that a reasonable estimate of population size in the Luangwa Valley is 600 individuals.

Between 1963 and 1965, 87% of the population consisted of mature individuals (Berry 1973). The field observations using direct counts in 2013 recorded between 71% and 74% of individuals as ‘mature’. Using a database of 20 reports generated from 15 research sites across Africa revealed that, on average, 70% of individuals within these Giraffe populations were mature (Muller et al. 2016). The relatively high proportion of mature individuals is probably a reflection of the relatively low calf survival rate (Bercovitch and Berry 2010b, Dagg 2014). Therefore, the population of Thornicroft’s Giraffe probably contains between 70% and 75% mature individuals. Given that the best estimate of the number of Giraffe is 600 individuals, then a population consisting of 70% mature animals would contain 420 mature Thornicroft’s Giraffe occupying an area of less than 5,000 km².

The Luangwa Valley has distinctive wet (November to April) and dry (May to October) seasons, with approximately 95% of the annual precipitation falling during the wet season (Bercovitch and Berry 2010b). The average annual rainfall in the Luangwa Ecosystem is reported to range from around 400 to 800 mm/year (Simukonda 2012). A diverse landscape characterises the Luangwa Valley, with Giraffe ranging in a variety of habitat types. The habitat consists of riparian forest (populated by Trichelia emetic, Tamarindus indica, Diospyros mespiliformis, Faidherbia aldiba, Kigelia africana, and others), mopane (Colophospermum mopane) and munga (mostly Acacia, Combretum, Terminalia) woodlands, miombo (Brachystegia, Julbernardia), thickets (Combretum, Acacia schweinfurtii, Capparis tomentosa), scrub brush, and open grassland (Astle et al. 1969, Fanshawe 1969, Berry 1973).

Giraffe subsist on an eclectic and variable diet, consuming flowers, leaves, stems, as well as grass, and feeding on at least 93 species of trees, plants, and fruits in the Luangwa Valley (Berry 1973, Berry and Bercovitch 2017b). Major dietary items include Kigelia africana, Tamarindus indica, and Capparis tomentosa, with the Giraffe restriction in distribution thought to depend upon the availability of Fluegga virosa (Berry 1973).

On average, first birth among Thornicroft’s Giraffe occurs at 6.4 years of age, with a mean inter-birth interval of 677.7 days (Bercovitch and Berry 2010b). Sex ratio among newborn calves is uniform, with a mortality rate of 45% in the first year of life. Maximum female lifespan is about 28 years (Bercovitch and Berry 2016), while maximum male lifespan is about 22 years, although most males do not live beyond 16 years of age (Berry and Bercovitch 2012). Variance in female reproductive success ranges from no births to production of 11 calves during a lifetime. Despite the pronounced seasonality in rainfall, Thornicroft’s Giraffe do not breed on a seasonal basis (Bercovitch and Berry 2010b). Given that the life history profile of female Giraffe includes a relatively late age at reproductive maturation, a low reproductive rate, and a high neonatal mortality rate, the maximum rate of population increase is low.

Since 1938, the sole range and habitat of the Thornicroft’s Giraffe has been protected, and local people are not considered to be a substantial threat to the Giraffe population. The tourist lodges in South Luangwa National Park and the neighboring GMAs employ many local people on their staff, with South Luangwa National Park visited by approximately 20,000 people per year. Ecotourism provides a buffer against threats posed to the Giraffe population. Although the local populations appear to pose little threat, other human activity and disease threats could pose future problems for the Giraffe population.

The human fertility rate in Zambia is one of the highest in the world, at 5.7 children per female (http://www.unicef.org/infobycountry/zambia_statistics.html), with a population growth rate of 2.7 to 2.8% over the last decade (Anon. 2011, UNICEF). Approximately two-thirds of South Luangwa National Park is within the Northern Province, with the remaining Thornicroft’s Giraffe range situated in parts of the Eastern and Central Provinces. The Northern Province has an annual population growth rate of 3.4%, while the Mpika District, within the Northern Province, has a population growth rate of 3.8%, one of the highest in Zambia. Mfuwe Village is the primary entry to South Luangwa National Park and lies within the Mambwe District in the Eastern Province. The Mambwe District had a population growth rate of 4.1% between 2000 and 2010. The growing population has fostered increased conversion of the natural habitat to agricultural areas and a diversion of water resources, which, if continued unabated, will result in Giraffe habitat loss. Any reduction in the regular flow of the Luangwa River and its tributaries for agricultural use could have devastating consequences for the Thornicroft’s Giraffe by drastically altering their only habitat

The confinement of the entire world’s population of Thornicroft’s Giraffe to the Luangwa Valley (none of the animals are present in any zoological collection in the world) renders them susceptible to extinction following any widespread catastrophic event. Diseases, such as anthrax, have had a history of devastating the wildlife population in South Luangwa National Park. In 1987, an anthrax plague swept the Luangwa Valley, killing over 4,000 hippopotami (Siamudaala 2003). The exact cause of the anthrax epidemic is unclear, but the area had sustained an extensive drought prior to 1987, and low rainfall, high temperatures, and poor drainage are some of the ecological factors that increase the probability of an anthrax outbreak (Siamudaala 2003). During the 1987 epidemic, the Thornicroft’s Giraffe was the second most vulnerable species, following the hippopotamus, with an estimated 7% of the population succumbing to anthrax (Siamudaala 2003). Anthrax re-occurred in the area in 1988 and 1989. The Times of Zambia (3 September 2011) reported that 120 human cases of suspected anthrax had been diagnosed in the Eastern Province, with all cases associated with contact with hippo carcasses from the Luangwa River. Anthrax remains a continuing threat to wildlife in the Luangwa Valley region.

The licensed hunting of Giraffe in Zambia was illegal until 2015. Although professional hunters can obtain a license to hunt Giraffes in Game Management Areas and on private land in Zambia, the stronghold containing a preponderance of Thornicroft’s Giraffe in Zambia is the South Luangwa National Park, an area off limits to legal hunting. The local populations in areas around SLNP are averse to eating Giraffe meat (Berry 1973) and within the last several years, only a single documented case of the direct poaching of Giraffe has been recorded. Snaring poses a direct threat to Giraffe, although the snares are probably aimed at other animals. Recently, up to five Giraffe per year have been reported to have been snared (R. McRobb pers. comm. 2014). Although snaring, poaching, and hunting of Giraffe pose potential threats to their existence, none of these human activities appears to be a major threat influencing Thornicroft’s Giraffe population size at present.

The increased mining activities in Zambia are a major cause of future concern. Although South Luangwa National Park is not directly affected by the mining industry, the lifeblood of the park is the Luangwa River. Should the river become a key source of water for mining, or polluted from mining extracts, or altered as a consequence of plans to build a dam downriver, then the wildlife within SLNP will confront a major problem. Zambia has the world’s second largest reserves of copper, with China the biggest foreign mining operation, extracting not only copper, but also coal, nickel, uranium, and gemstones (Okeowo 2013). Chinese investors are expanding mining operations in Zambia, including some that are illegal (Charles Sakata, Zambia Reports, 8 April 2014, 23 April 2014). In 2011, an Australian mining company was granted a 25-year lease to mine copper in the Lower Zambezi National Park (Steyn 2014), creating a situation where the wildlife resident in a national park is not necessarily protected from mining or other extractive industries. Although the Zambian Court ruled that the granting of the permit was illegal, thereby revoking the permission to mine, the threat remains. The continued expansion of mining operations in Zambia poses a threat to the wildlife of the country, including Thornicroft’s Giraffe. At present, the Zambian government is considering the Ndevu Gorge Power Project, which would involve construction of a dam about 1,000 km south of the southern boundary of SLNP. The dam, if built, would interfere with the flow of the Luangwa River, create a lake that extends north into SLNP, and could have detrimental and serious consequences for Thornicroft’s Giraffe and other species (Conlen et al. 2017).

Natural catastrophes and environmental stochasticity can wreak havoc on small populations. Any drought or extensive fires within the Luangwa Valley could have a severely negative impact on wildlife. The Thornicroft’s Giraffe is an isolated population of about 600 individuals living in a single location with an EOO of less than 5,000 km². The major threats to the Thornicroft’s Giraffe are anthropogenic factors deriving from a population explosion accompanied by mineral extraction and resource use that could hinder the free-flow of the Luangwa River.

Because Thornicroft’s Giraffe resides in only one limited location, should anthropogenic factors, such as climate change, water pollution, diversion of water for agriculture or mining, worsen, or epidemic diseases, such as anthrax, infect the population, then the entire subspecies could be devastated.

No significant use and tarde.

Since 1938, the range and habitat of Thornicroft’s Giraffe has been protected. Giraffe are a protected species under the Zambia Wildlife Act of 2015. Since 2015, permits may be applied for to hunt Giraffe in Game Management Areas a(GMA) and on private land. However, Thornicroft’s Giraffes reside primarily in a national park where legal hunting is forbidden. Their stronghold is in South Luangwa National Park (SLNP), and the adjacent Lupande MA.

Thornicroft’s Giraffe are not found in any zoological institutions.