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The information compiled here is part of:
Borries, Lu, Ossi-Lupo, Koenig (202x). Data from: Timing of conceptions in Phayre’s leaf monkeys: energy and phytochemical intake [Dataset]. Dryad. https://doi.org/10.5061/dryad.n02v6wx3v
which is related to an accepted manuscript in American Journal of Biological Anthropology, (Borries, Lu, Ossi-Lupo & Koenig, AJPA-2023-00136.R1)

The data were observational in nature. Of the 78 total conceptions used in the analyses, 71 were based on the day of detection of a newborn in the study groups from which the mean gestation length (205 days) was subtracted to find the conception date. The 7 additional conceptions were determined via hormone analysis of fecal material (Lu, Borries, Czekala & Beehner, 2010).

Due to a few gaps in observations, not all births were known to the day and were estimated based on the state of infant development as well as skin and coat color at the time of detection. Phayre’s leaf monkeys are born with a pale pinkish skin and a bright orange fur which changes gradually and predictably to the adult grey color over the course of several months, thus facilitating age estimates of small infants (Borries, Larney, Lu, Ossi & Koenig, 2008; Larney, 2013).

File ‘all_conceptions’
This file lists all 78 conceptions included in the analysis with each row representing one conception. They refer to 39 females from 4 study groups during 21 complete group years between July 2001 and June 2008.

From left to right, the columns contain:

‘parity’ of the female, coded as

• multiparous = adult female known to have had at least one prior offspring.
• primiparous = the first conception of a nulliparous female.
• unknown = female could be primiparous or multiparous.

‘current_offspring’ of the female, coded as:

• dead = female had an offspring which had died or disappeared by the time of this next listed conception.
• living = female has a living offspring at the time of this next listed conception.
• none = primiparous female, has not yet given birth for the first time and has no offspring.
• unknown = female was not yet known at the time of conception but was known when she gave birth so that the conception date could be calculated.

‘group_of_residency’ of the female, coded as:

• same = the conception listed here took place in the same group as the previous one (when the current offspring was conceived), i.e., no dispersal took place between these 2 conceptions.
• new = female dispersed into another group between conceptions.
• unknown = female residency unknown at the time of conception but known when she gave birth.
• irrelevant = primiparous females have no prior conception for comparison. Per definition, they conceive for the first time in their life.

‘conception_day’ provides the conception day of the month to illustrate how the ‘conception_day_of_the_year’ was found.

‘conception_month’ provides the conception month to illustrate how the ‘conception_day_of_the_year’ was found and to facilitate plotting of the data.

‘conception_day_of_year’ provides the conception dates in day-of-the-year format (considering the respective (leap) year) for testing of seasonal effects and between subsamples.

‘conception_known_or_calculated’ coded as

• calculated = the conception date was found by subtracting 205 days (the mean gestation length, Lu et al., 2010) from the date of parturition.
• known = the conception date was determined based on changes in hormone levels extracted from fecal samples (Lu et al., 2010).

File ‘re_conceptions’
The file provides information on the period leading up to re-conceptions by listing presumed conditions regarding high fecal progestin concentrations and positive energy balance for the respective time period. The data refer only to multiparous females with a living offspring at the time of re-conception and excludes females who dispersed into another group. The listing begins with the seventh month after parturition (third column) for each individual female (first column) / infant (second column) combination because the earliest re-conception in the population occurred in month 8 postpartum.
Each month is characterized (1/0) as

• high fP period, i.e., consecutive months when fecal progestin metabolite concentrations were significantly elevated. It is assumed that this effect is related to the intake of leaves and fruits from Vitex trees (Lu et al., 2011). Each year the high fP period was set to begin one month after the onset of the respective wet season (when at least 50 mm of rain fell per month, Walter, 1990) and to last until September inclusively.
• high energy period, i.e., consecutive months which begin after the energy balance is assumed to have been positive for at least three months. Based on data from a complete year (Suarez, 2013) fruit feeding increased 3 months after the onset of the wet season. Therefore, the beginning of increased fruit feeding (i.e., a positive energy balance) in other years was determined relative to the wet season. After 3 consecutive months of positive energy balance, the high energy period begins. It is estimated to last until December inclusively each year. Depending on the respective year (variable onset of the wet season), the high energy period is estimated to last either 3 or 4 months.
• re-conception, the month when the female conceived again was indicated as ’1’ and thereafter the female is removed from the sample for this re-conception.
  Females and infants are anonymized as numbers, but females contributing more than once to the dataset are identified by the same number. Consecutive offspring numbers for an individual female do not necessarily represent the birth order, because offspring who died prior to re-conception were not included here.

Relationship between the two datasets
The data compiled in the file named ‘re_conceptions’ are a subsample of the data compiled in the file named ‘all_conceptions’. Only re-conceptions in multiparous females with a living offspring at the time of re-conception were considered (28 cases for 17 females) in the file ‘re_conceptions’. For these 28 cases, additional information is provided in the file ‘re_conceptions’ beginning with month 7 after parturition. We excluded 22 additional conceptions because the multiparous female had not conceived again when the study ended (some females disappeared, others dispersed, or the last parturition took place very late in the study).

File ‘interbirth_intervals’
Interbirth intervals [in months] for multiparous females with a living offspring at the time of re-conception are listed in relation to when the conception occurred (peak versus off-peak, details below). There is no direct relationship to the data in the other two files.

From left to right, the columns contain:
‘peak_versus_off_peak’

• peak = the conception leading to the birth of the first infant of the interbirth interval occurred during the conception peak from May to August
• off-peak = the conception leading to the birth of the first infant of the interbirth interval occurred during off-peak from September to April.

‘interbirth_interval’

• Holds the numeric value of each interbirth interval [in months] that began with the respective conception.

References

Borries, C., Larney, E., Lu, A., Ossi, K., & Koenig, A. (2008). Costs of group size: lower developmental and reproductive rates in larger groups of leaf monkeys. Behavioral Ecology, 19, 1186-1191. https://doi.org/10.1093/beheco/arn088.

Borries, C., Lu, A., Ossi-Lupo, K., & Koenig, A. (in revision). Timing of conceptions in Phayre's leaf monkeys: energy and phytochemical intake. American Journal of Biological Anthropology.

Larney, E. (2013). The influence of genetic and social structure on reproduction in Phayre's leaf monkeys (Trachypithecus phayrei crepusculus) dissertation thesis. Stony Brook University, Stony Brook.

Lu, A., Beehner, J. C., Czekala, N. M., Koenig, A., Larney, E., & Borries, C. (2011). Phytochemicals and reproductive function in wild female Phayre's leaf monkeys (Trachypithecus phayrei crepusculus). Hormones and Behavior, 59, 28-36. https://doi.org/10.1016/j.yhbeh.2010.09.012.

Lu, A., Borries, C., Czekala, N. M., & Beehner, J. C. (2010). Reproductive characteristics of wild female Phayre's leaf monkeys. American Journal of Primatology, 72, 1073-1081. https://doi.org/10.1002/ajp.20866.

Suarez, S. A. (2013). Diet of Phayre's leaf-monkey in the Phu Khieo Wildlife Sanctuary, Thailand. Asian Primates Journal, 3, 2-12.

Walter, H. (1990). Vegetation und Klimazonen. Stuttgart: Eugen Ulmer.