Wingfield, J. C., Hau, M., Boersma, P. D., Romero, L. M., Hillgarth, N., Ramenofsky, M., et al. (2018). Effects of El Niño and La Niña Southern Oscillation events on the adrenocortical responses to stress in birds of the Galapagos Islands. General and Comparative Endocrinology, 259, 20-33. doi:10.1016/j.ygcen.2017.10.015.