Adding herbs to bird nests makes starlings better parents

June 6 (UPI) — Starlings with aromatic herbs in their nest exhibit improved parenting behaviors, according to a new study by researchers at North Carolina State University.

For the study, scientists swapped out 36 natural starling nests for artificial nests. Half of the nests featured dry grasses and a combination of aromatic herbs, including milfoil, hogweed, cow parsley, black elder, goutweed and willow. The other half featured only grasses.

Artificial eggs with temperature sensors were added to the each nest’s clutch, helping scientists monitor the birds’ incubation performance.

“Egg temperatures and nest attendance were higher in herb than nonherb nests — particularly early in the incubation period,” ecologist Caren Cooper said in a news release. “In addition, egg temperatures dropped less frequently below critical thresholds in nests that contained herbs, and those parents started their active day earlier.”

The herbed and non-herbed nests yielded the same percentage of successfully hatched eggs, but chicks from herbed nests showed signs of accelerated development and were quicker to gain body mass after hatching.

Though the data suggests the presence of herbs has a positive effect on the health of parents and chicks, researchers aren’t sure how or why.

“It’s possible that one or more of the herbs have pharmacological effects on the parents,” said Helga Gwinner, researcher at the Max-Planck Institute for Ornithology in Germany.

Some of the herbs starlings choose to decorate their nests with are also used in folk medicine remedies. Several have sedative effects, which could encourage birds to remain on their nests, limiting their egg’s exposure to less-than-optimal temperatures.

Researchers published their findings this week in the journal Proceedings of the Royal Society of London B.