A recent study published in Communications Biology found that wolves infected with Toxoplasma gondii in Yellowstone, USA, were more than 46 times more likely to become pack leaders than uninfected wolves.
These findings show for the first time how parasitic infections affect wolf decision-making and behavior.
Researchers analyzed data on wolf pack behavior and distribution over a 26-year period (1995-2020), as well as Toxoplasma antibodies in blood samples from 229 wolves, and identified an association between parasite infection and high-risk behavior in both females and males.
Compared to uninfected wolves, Toxoplasma-positive wolves were 11 times more likely to disperse from the pack and 46 times more likely to become pack leaders.
Males were 50% more likely to leave the pack within 6 months of infection with the parasite, compared to about 21 months for uninfected individuals.
Previous studies have found that Toxoplasma gondii infection is associated with an increase in bold and adventurous behavior in hyenas and increased testosterone production in rats.
The researchers hypothesize that there are similar mechanisms driving the risk-taking behaviors observed in wolves that test positive for the parasite.