Here we examine the patterns of reproductive hormones (progesterone and estrone-3 glucuronide, or E1G) in one female hoolock gibbon (Hoolock leuconedys) housed at the Gibbon Conservation Center, throughout the maturation period. Three hundred forty-five fecal samples were collected from the individual over a 5-year period (2012–2017) beginning at the age of 6 years and ending at the age of 11. The average measured progesterone concentration increased from 19.572 ± 1.706 ng/g feces in 2012 to 107.922 ± 12.094 ng/g feces in 2016/17 (p < 0.00001). The average measured estrogen value increased from 1.234 ± 0.063 ng/g feces in 2012 to 2.783 ± 0.274 ng/g feces in 2016/17 (p < 0.00001). This was accompanied by the emergence of a clear hormonal cycling pattern in the 2016/17 samples that was absent in all earlier samples. These data are consistent with the known sexual maturation period for other gibbon species, which typically occurs between the ages of 6 and 8 but shows some variation. To our knowledge, this is the first hormonal study and first data on cycle length for a hoolock gibbon.

Keywords:
Hoolock gibbon, Cyclicity, Progesterone, Estrone-3 glucuronide
1.
Arbor Assays (2021a). DetectX estrone-3-glucuronide (E1G) enzyme immunoassay kit.
2.
Arbor Assays (2021b). DetectX progesterone enzyme immunoassay kit.
3.
Atsalis S, Margulis SW (2006). Sexual and hormonal cycles in geriatric Gorilla gorilla gorilla. International Journal of Primatology 27: 1663–1687.
4.
Bolechová P, Chaloupková H, Hradec M, Jánová E, Doležalová J (2019). Fur color change and hormonal development in captive females of northern white-cheeked (Nomascus leucogenys) and buff-cheeked (Nomascus gabriellae) gibbons. General and Comparative Endocrinology 282: 113219.
5.
Brown JL, Bellem AC, Fouraker M, Wildt DE, Roth TL (2001). Comparative analysis of gonadal and adrenal activity in the black and white rhinoceros in North America by noninvasive endocrine monitoring. Zoo Biology 20: 463–486.
6.
Choudhury A (1996). A survey of hoolock gibbon (Hylobates hoolock) in southern Assam, India. Primate Report 44: 77–85.
7.
Choudhury A (2006). The distribution and status of hoolock gibbon, Hoolock hoolock, in Manipur, Meghalaya, Mizoram, and Nagaland in Northeast India. Primate Conservation 20: 79–87.
8.
Dielentheis TF, Zaiss E, Geissmann T (1991). Infant care in a family of siamangs (Hylobates syndactylus) with twin offspring at Berlin Zoo. Zoo Biology 10: 309–317.
9.
Fan PF, Xiao W, Huo S, Ai HS, Wang TC, Lin RT (2011). Distribution and conservation status of the Vulnerable eastern hoolock gibbon Hoolock leuconedys in China. Oryx 45: 129–134.
10.
Geissmann T (1991). A reassessment of age of sexual maturity in gibbons (Hylobates spp.). American Journal of Primatology 23: 11–22.
11.
Geissmann T, Anzenberger G (2009). Hormonal correlates of the ovarian cycle in the yellow cheeked crested gibbon (Nomascus gabriellae), and a review of ovarian cycles in gibbons (Hylobatidae). Gibbon Journal 5: 61–73.
12.
Israfil H, Zehr SM, Mootnick AR, Ruvolo M, Steiper ME (2011). Unresolved molecular phylogenies of gibbons and siamangs (Family: Hylobatidae) based on mitochondrial, Y-linked, and X-linked loci indicate a rapid Miocene radiation or sudden vicariance event. Molecular Phylogenetics and Evolution 58: 447–455.
13.
IUCN (2021). The IUCN Red List of Threatened Species. Version 2021-1 (cited 2021 Jun 3]. Available from: https://www.iucnredlist.org.
14.
Lukas KE, Barkauskas RT, Maher SA, Jacobs BA, Bauman JE, Henderson AJ, Calcagno JM (2002). Longitudinal study of delayed reproductive success in a pair of white-cheeked gibbons (Hylobates leucogenys). Zoo Biology 21: 413–434.
15.
Margulis SW, Hálfdanardóttir MR (2021). Hormones and color change in female white-cheeked gibbons, Nomascus leucogenys. International Journal of Primatology 42: 201–219.
16.
Meyer TJ, McLain AT, Oldenburg M, Faulk C, Bourgeois MG, Conlin EM, et al (2012). An Alp-based phylogeny of gibbons (Hylobatidae). Molecular Biology and Evolution 29: 3441–3450.
17.
Mootnick AR, Fan PF (2011). A comparative study of crested gibbons (Nomascus). American Journal of Primatology 73: 135–154.
18.
Orgeldinger M (1989). Untersuchungen zum Verhalten von Siamangs (Hylobates syndactylus, Raffles, 1821) in zoologischen Gärten unter besonderer Berücksichtigung des Sozialverhaltens. Diploma thesis, Fakultät für Biologie, Ruprecht-Karls-Universität Heidelberg.
19.
Rafacz ML, Margulis SW, Santymire RM (2013). Hormonal and behavioral patterns of reproduction in female hylobatids. Animal Reproduction Science 137: 103–112.
20.
Schultz AH (1973). The skeleton of the Hylobatidae and other observations on their morphology. Gibbon and Siamang 2: 1–54.
21.
Takacs Z, Morales JC, Geissmann T, Melnick DJ (2005). A complete species-level phylogeny of the Hylobatidae based on mitochondrial ND3-ND4 gene sequences. Molecular Phylogenetics and Evolution 36: 456–467.
22.
Tilson RL (1979). On the behavior of the hoolock gibbons (Hylobates hoolock) during different seasons in Assam, India. Journal of the Bombay Natural History Society 76: 1–16.
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2021
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