Northern & Southern Giant-Petrel (Macronectes giganteus, Macronectes halli)

Here are both species of Giant-Petrel side-by-side. An adult Northern Giant-Petrel on the left shows a reddish bill tip while a dark morph adult Southern Giant-Petrel on the right shows a pale greenish-gray bill tip. Note light eyes indicating adults. Southern is marginally larger than Northern and has a slightly paler head. Mixed pairs comprise up to 2% of the South Georgia population but identification of hybrids after they leave the nest remains elusive. Northern breed earlier than Southern limiting potential hybridization (Brown et al. 2015).