Penguins are highly social birds. They swim and feed in groups. When they come ashore, they nest in huge colonies called rookeries. There may be hundreds of thousands of penguins in a rookery. Within the rookery, they form small groups of 5 to 20.
One of my questions is, “How do they find one another among the thousands?” From one penguin to the next, there is not much difference in appearance. The trusty internet tells me that vocalization is the method they use.
Perhaps this is similar to you being in a big crowd when someone says your name. Your ears perk up when you hear your name. You wonder if it is someone trying to get your attention or if it is someone talking about you? Either way, they have your interest.