The Older the Better: Infanticide Is Age-Related for Both Victims and Perpetrators in Captive Long-Tailed Macaques
Karlijn Gielen1, Annet L Louwerse2, Elisabeth H M Sterck1,2
1Animal Behaviour and Cognition, Department of Biology, Utrecht University, 3508 TB Utrecht, The Netherlands.
Insights
Infanticide in captive primates, particularly long-tailed macaques, is linked to infant age and the age of new alpha males. Young males pose a risk, highlighting the need for careful male introductions to prevent infant mortality.
Area of Science:
- Primate behavior
- Animal conservation
- Reproductive strategies
Background:
- Infanticide is a significant threat in wild primate populations, especially during male takeovers.
- Understanding infanticide risk factors can help reduce infant mortality in captive settings during male introductions.
Purpose of the Study:
- To investigate wild-derived infanticide risk factors in captive long-tailed macaques (Macaca fascicularis).
- To identify specific captive-related risks, such as the "adolescent male risk hypothesis."
Main Methods:
- Analysis of demographic data spanning 25.5 years in captive long-tailed macaques.
- Testing hypotheses explaining infanticide in wild primate populations.
Main Results:
- Wild-derived factors explained some, but not all, captive infanticide cases.
- Infants with shorter interbirth intervals (<215 days) were at higher risk.
- Infanticidal males were significantly younger (by over 2.5 years) than non-infanticidal males.
Conclusions:
- Infant age and male age are critical factors in captive infanticide.
- Captive settings may present unique risks, with young, subadult males posing a threat (adolescent male risk hypothesis).
- Consideration of male and infant ages is crucial during captive male introductions to mitigate infanticide.
Abstract:
In wild primates, infanticide is a risk that is especially prevalent when a new male takes over the alpha position. Insight into risk factors related to infanticide may decrease the incidence of infanticide in captivity during male introductions. We investigated several risk factors of infanticide derived from hypotheses explaining infanticide in the wild and tested this in captive long-tailed macaques (Macaca fascicularis) using demographic data spanning a 25.5-year period. Factors that are related to infanticide in the wild explained a large proportion, but not all incidences, of infanticide in captivity. Consistent with the wild data, infants young enough to decrease the interbirth interval (<215 days) were at risk of being killed. In contrast to studies from the wild, infanticidal males were more than 2.5 years younger than non-infanticidal males. This indicates that captive settings can lead to new risks since relatively young males may gain the alpha position, promoting infanticide. Therefore, we propose the adolescent male risk hypothesis as a captive risk factor in which subadult males pose a risk of infanticide. In conclusion, the ages of both males and infants are related to infanticide in captivity and have to be taken into account during male introductions.
Related Concept Videos
00:55Parental Care
02:07Conservation of Declining Populations
01:27Correlation and Causation
Correlation versus Causation
If the dependent variable increases or decreases when the independent variable increases, there is a positive or negative...
01:20Attachment
01:29Life Histories
03:09Meiosis I
Prophase I is the most extended and complex step of meiosis I characterized by synapsis, chromosome pairing, and recombination of the homologous chromosomes. This process is facilitated by a proteinaceous structure called the...