The houbara bustard (Chlamydotis undulate) is a bird that inhabits dry scrublands in Northern Africa. The bird suffers one of the downfalls of growing older, and one that afflicts several other animal species. This is a declining reproductive fitness.
In relation to this biologists are studying a decade of data gathered from birds involved in a captive breeding program. The research has provided an interesting assessment at just how bad it gets for older bustards, especially males.
Houbara bustards can live in excess of 20 years. Despite this relative long longevity, scientists have discovered that after age 6, both males and females experienced declines in the performance of their respective gametes.
On studying 10 years’ worth of data collected at a Moroccan breeding, where staff had monitored the artificial insemination of more than 1,000 birds, recording egg hatching success and growth in resulting chicks. With bustards ranging in age from 1 to 23, the scientists were able to monitor reproductive success as the birds aged.
The biologists found that eggs made from inseminating older females with sperm from older males were less likely to hatch. Furthermore, they discovered that males that were a decade removed from their reproductive prime—three to six years old—were 7 percent more likely to create eggs that wouldn’t hatch than younger males. Of the eggs that did hatch, those chicks fathered by older bustards grew slower through their first month of life than birds that resulted from a mating of younger parents.
The scientists suggest that the root of the age-related gamete decline lay in DNA that sperm deliver to egg cells. Older birds likely make sperm with more accumulated DNA damage and mutations than younger birds.
It is likely that the same thing exists in many species beyond bustards. This could include humans and this represents an area for further research.
The research has been published in the journal Nature Communications. The research is titled “The sperm of aging male bustards retards their offspring’s development.”
