Reproduction and Development of the Released Przewalski's Horses (Equus przewalskii) in Xinjiang, China

Abstract

In China, the first Przewalski’s horse (Equus przewalskii) group was released in Kalamaili Ungulate Protected Area in Xinjiang, in August 2001. The objective of this study was to investigate reproduction and development of released Przewalski’s horses in Xinjiang, China from 2002 to 2006. Twenty-four descendants were naturally born, average reproduction rate was 38.7%, and average survival rate of foals was 69.1% in this interim. Frequent alternation of the leading stallion and infertility in female horses due to environmental factors were main causes for the low reproduction rate. The infant mortality rate of released Przewalski’s horses was 25.0%, and 83.3% of death in infants was due to the leading stallion infanticide. The released Przewalski’s horses exhibited seasonal breeding, 70.8% of infants were born in May and June. The fertility rates were 8.3% in April and 37.5% in May, which were lower compared to those of the captive Przewalski’s horse groups (18.3% and 44.3%, respectively). Furthermore, the fertility rate in June was 33.3% and higher than the captive groups (18.3%). These findings showed that the breeding peak of the released Przewalski’s horse groups was later than the captive groups, and suggested that the altered survival environment and food supplies were the main reasons contributing to the delayed breeding peak.

Retracted: Przewalski's Horses in Western China: When will reintroduction succeed?

“…Our study shows that food shortage is the main reason for the low reproductive rate of Przewalski's Horses in the wilderness in the Gobi Desert (Chen et al 2008).…”

Gut Microbiomes of Endangered Przewalski’s Horse Populations in Short- and Long-Term Captivity: Implication for Species Reintroduction Based on the Soft-Release Strategy

“…To enhance the ability of a founder group to settle during release, soft release strategies, wherein animals experience a period of confinement at the release site, are regularly used for animal reintroduction (Clarke et al, 2002;Hardman and Moro, 2006). In Xinjiang, China, the first captive PHs were released into the Kalamaili Nature Reserve (KNR) in 2001 (Chen et al, 2008;Xia et al, 2014). This reserve is located in the northeastern part of the Junggar Basin with a harsh continental-type local climate.…”

“…Before driven into captivity, Stipa, Pamirian, Artemisia and Anabasis are the major food plant genera of Przewalski's horses (Meng, 2007). PHs range freely from spring to late fall, and then are driven back into captivity during the severe winters to allow them to adapt to the local environment step by step (Chen et al, 2008;Xia et al, 2014).…”

Reproduction and Mortality of Re-introduced Przewalski’s Horse Equus przewalskii in Hustai National Park, Mongolia

“…The reproduction rate of free-roaming mares in Hustai National Park was 25.0-89.0% on average. It is higher than the 38.7% Chen et al (2008) of the Kalamaili Ungulate Protected Area in Xinjiang, China [5], 50% Feist and McCullough (1975) state for feral horses in the USA [6], but goes along with the 61% Keiper (1985) reports for feral ponies [7]. High percentage of reproduction rate may correlate with the even sex ratio of between stallions and mares.…”

“…The low reproduction rate among released Przewalski's horses in Kalamaili Ungulate Protected Area in China, caused by frequent alternation of the leading stallion and its infanticide, Ref. [5] suggests an even male-female ratio. Initially the sex ratio of horses transported to Hustai NP in Mongolia was 1 male: 2.5 female with actual numbers of 24 and 60 respectively.…”