The role of flower consumption in Howler Monkey Females’ diet: adjustment across reproductive states

Background Although the genus Alouatta is considered a folivore and frugivore species, the consumption of vegetative parts like flowers often represents a considerable percentage of their diet. Flowers are high in tannins and flavonoids, which are beneficial for the animals due to the antioxidant and anti-inflammatory properties. However, there is a notable lack of knowledge regarding the role of flowers in howler’s diet, especially for the specific needs of females. The objective of this study is to gain further insight into the role of flowers for howler monkey females’ diets during lactation. Methods Between 2021 and 2023, we collected data on the feeding behavior of 20 wild Alouatta palliata mexicana females during non-lactation, early lactation and late lactation on the Agaltepec Island, Mexico. Results In 670 contact hours, a total of 1,471 feeding sessions were recorded. From 29 documented feeding items, five were flowers from the trees of Andira galeottiana , Bursera simaruba , Dendropanax arboreus , Gliricidia sepium and Spondias mombin . Documented feeding items were collected and evaluated for their tannin and flavonoid content. The annual weight-based flower consumption was 12.5%, which increased to 30.3% during blooming months. The tannin content of the flower species exhibited considerable variation, with levels ranging from 0 to 2,038.0 µg/g. In contrast, the qualitative evaluation of principal groups of flavonoid content detected a pronounced presence of flavanones in all five species and flavones in three. Notably, early lactating females exhibited a higher consumption of flowers compared to non-lactating and late lactating females. Conversely, the floral tannin intake was the highest in late lactating and lowest in early lactating females. Our findings suggest that dietary choices of howler monkey females are influenced by seasonal flower availability, with polyphenols playing an important role, suggesting physiological and behavioral adaptations in response to reproductive demands.