Ovarian cycle approach by rectal temperature and fecal progesterone in a female killer whale, Orcinus orca

Dominance rank and the presence of sexually receptive females predict feces-measured body temperature in male chimpanzees

Quantifying the costs of mating is key for understanding life-history trade-offs. As a reflection of metabolic rate, body temperature is one metric for assaying these costs. However, conventional methods for measuring body temperature are invasive and unsuitable for the study of free-living populations of endangered species, including great apes. A promising proxy for body temperature is fecal temperature, the internal temperature of fecal deposits shortly following defecation. We validated this method with humans, finding that maximum fecal temperature is a reliable proxy for rectal temperature. We then applied this method to wild chimpanzees (Pan troglodytes schweinfurthii) at Ngogo, Kibale National Park, Uganda. We collected and analyzed 101 fecal temperature measurements from 43 adult chimpanzees (male: N = 28; female: N = 15). Chimpanzee fecal temperature ranged from 33.4 to 38.9 °C, with a mean of 35.8 °C. Although fecal temperature was not predicted by sex, age, or ambient temperature, male fecal temperature was 1.1 °C higher on days when sexually receptive females were present and was positively correlated with male dominance rank. Post hoc analyses showed that overall copulation rates, but not aggression rates, were positively correlated with fecal temperature, suggesting that sexual physiology and behavior best explain mating-related temperature variation. Together, these results indicate fecal temperature is a reliable proxy for core body temperature in large-bodied mammals, captures metabolic costs associated with male mating behavior, and represents a valuable noninvasive tool for biological field research.

Characterization and longitudinal monitoring of serum progestagens and estrogens during normal pregnancy in the killer whale (Orcinus orca)

The secretory patterns of progestagens and estrogens were characterized throughout 28 normal pregnancies until two month post-partum in eleven killer whales. HPLC analysis of serum from different reproductive stages (luteal phase, EARLY, MID, and LATE pregnancy) identified three major immunoreactive progestagen peaks; progesterone (P4), 5α-pregnane-3,20-dione (5α-DHP) and pregnanediol, with 5α-DHP approximately half of that for P4 in the luteal phase, and EARLY, but approximately 2/3 of P4 during MID and LATE pregnancy. At birth, 5α-DHP was the only significant (>10% immunoreactivity) immunoreactive progestagen detected in placental (umbilical cord) serum. Maternal recognition of pregnancy appears to occur between day 21 and 28 post-ovulation when a significant deviation in progestagen concentrations between conceptive and non-conceptive cycles was detected. Progestagen concentrations during pregnancy displayed a bimodal pattern with significant peaks (P<0.05) in EARLY (indexed month post-conception [IMPC] 2, 3, 4) and MID (IMPC 9, 10) before decreasing (P<0.05) over an 11day interval to luteal phase concentrations on the day of parturition. Among estrogens, estriol was secreted in the highest concentrations but only estrone (free and conjugated) and estradiol increased (P<0.001) during pregnancy, with peaks observed during the final month of gestation, and an influence (P<0.05) of fetal sex on estradiol production was detected. Collective findings indicate that P4 derived from the corpus luteum is the major biologically active progestagen during the luteal phase and pregnancy, and that 5α-DHP production, possibly from both luteal and placental sources, increases during the second half of pregnancy.