Vertical dotted lines = time of putative conception (left dotted line) and sibling birth (right dotted line). Data points represent the proportion of time and circle size the underlying sample size (square-rooted; ranges: riding 3–44, all other behaviors 3–303). All smooths are not controlled for age to show cumulative pattern. 95% confidence intervals are plotted. Left-hand plots (A, D, G, J): sex-specific trajectories around sibling birth (blue: males; red: females). Middle plots (B, E, H, K): age-specific trajectories around sibling birth for offspring that were older (purple) or younger (yellow) than the median value of 5.1 years at sibling birth. Right-hand plots (C, F, I, L): interaction plots visualizing how trajectories around sibling birth change with increasing offspring age at sibling birth (scale from dark green [lowest levels] to brown [highest levels]; white space: extrapolation would be unreliable due to lacking data) for the respective perspective plots, see Figure 2—figure supplement 1. (A–C) Proportion of time spent suckling decreased to zero already before sibling birth (A) and was largely absent in older offspring (B, C), without a sudden change at sibling birth. (D–F) The proportion of time riding on the mother showed a significant and sudden decline at sibling birth (D), but this cut was evident only in offspring younger than 5 years old at sibling birth and not anymore in older offspring (E, F). (G–I) The proportion of time spent in body contact with the mother showed a significant and sudden increase at sibling birth, irrespective of the sex or age of the offspring. (J–L) The proportion of time in 5 m proximity to the mother decreased around sibling birth, but this effect was indiscernible from a general age effect. There was no significant sudden change at sibling birth (J), and there was no significant effect of offspring age at sibling birth (K, L).