How Birds and Other Creatures Use Medicinal Plants
“‘Not all pharmacists are human.’ So begins a 1993 review article on the use of medicinal plants by animals. Reading on, we learn that pharmacists can be chimpanzees, Kodiak bears, starlings and grackles. As we learn more about how animals use plants to prevent and treat ailments, this list has only continued to grow. It now even includes caterpillars.
Self-medication defined: When a substance is deliberately sought out that prevents or cures a condition and its use results in increased survival and reproduction.
For example, if you get an infection, you take antibiotics that cure the infection which might otherwise kill you.
A non-human example concerns starlings. These birds deliberately choose specific plants (that they find with their sense of smell) to include in their nests. The aromatic compounds emitted by these plants boost immune systems of chicks and reduce their bacterial loads.
Yarrow (Achillea millefolium) is one of the plants used by starlings, along with goutweed (Aegopodium podagaria), hogweed (Heracleum sphondylium), elder (Sambucus niger), cow parsley (Anthriscus sylvestris) and white willow (Salix alba).
A subsequent experiment added yarrow to the nests of tree swallows, which don’t normally use medicinal plants. The result: the abundance of blood-sucking fleas was reduced in nests containing the plant.
Corsican blue tits also add plant material to their nests. They use lavender (Lavandula stoechas), mint (Mentha suaveolens) and an aster (Helichrysum italicum).
These birds add fresh plant fragments throughout the nesting period. When researchers experimentally removed these aromatic plants from their nests, the birds quickly replaced them.
For good reason it seems – chicks in nests with aromatic herbs had higher body and feather growth rates. The herbs also reduce the amount of and diversity of bacteria living on chicks.
Eagles and wood storks choose nesting material from trees and shrubs containing insect-repellent resins. Bonelli’s eagles preferentially use pine boughs for nest construction. Nests with a greater pine composition have lower parasite levels and fledge more young eagles.
Research demonstrated that cigarette butts reduce the parasites in nests.
The twist is that, as we’ve learned ourselves, synthetic chemicals can have unintended consequences. In the case of house finches, chicks from nests full of cigarette butts have increased chromosomal abnormalities.
Remarkably, every single plant mentioned above has a long history of medicinal uses by humans…”