Territoriality: What, How, and Why it Matters in Species’ Reintroductions

Many animals are territorial as adults. This strategy often makes evolutionary sense since animals can defend clumped resources more efficiently if they stake out a space of their own.

Territorial species’ social systems have adapted around this concept, which shapes some of what the animals learn and how they communicate. Animals will learn the boundaries and owners of adjacent territories, which reduces the need for conflict once territories are laid out. Territoriality has also led to powerful, yet sometimes beautiful modes of species’ communication across the animal kingdom.

For instance, intricate bird song, haunting duets by gibbon pairs, and wolves’ displays of strength and submissive body postures all relate back to territory defense.

In species’ reintroduction programs, the territoriality of released animals often needs to be considered when planning where and how many animals to release.

Meanwhile, after release, the onset of territorial behavior can serve as a clue into whether animals are settling into their new home.

As a natural species-specific behavior, monitoring the development and display of territoriality helps us better understand the movements and interactions of individuals. For instance, when animals are first forming territories, it is not unusual for brief periods of conflict to erupt, as individuals start defending areas and figuring out the boundaries of where they want to defend. 

In ‘alalā, we have begun to see precursors to territory formation, which is a huge milestone in the program. Not only does it mean that the birds released in 2017 have survived long enough in the wild to reach maturity, but territorial defense is also an encouraging sign these birds may attempt to breed in future.

The morning dawns are now punctuated with territorial broadcast calls from different areas of the forest, as some of our older males have begun stating their intentions to the others. Some birds are showing signs of joint territory defense and are even engaging in pair-bonding behavior.

For example, one male and female (Ho’oikaika and Lili’uwelo) have taken to streaming through the branches together, calling and warding off younger birds from a section of the forest. This potential pair is often seen making cooing noises to each other and preening (grooming each other) as their relationship and bond deepens. They still take long distance ventures to various corners of the natural area reserve where they live, so it seems they haven’t yet solidified their territory, but their behavior is encouraging. 

We have also responded to some of the challenges of territory formation. The act of forming territories can lead to conflict, which is a natural part of the life cycle of many territorial species. We recently had to return one of the birds, Kalokomaika’i, to our conservation breeding facility for a stint of rehab, following an injury from a territorial fight.

The team had been closely watching potential aggression between males and was able to quickly rescue him. He is currently receiving veterinary care under consultation with the vets based in San Diego and locally in Hilo, Hawai’i. He is planned for re-release once his injury heals.

Additionally, we have been proactive in moving food around the landscape to minimize aggression between older and younger birds in anticipation of potential conflict. So far, the majority of birds have been coexisting well, but we expect more pairings and territory formation in the future, which would be a great thing for the success of the species. 

As the team continues to track the sights and sounds of territorial behavior, we have yet another indication that the ‘alalā are returning to the wild. We won’t be able to control their behavior, nor should we try to necessarily.

However, it is more important than ever that we are able to track the birds’ behavior and support them when needed as they reach this new and exciting stage of life. 

(Photo above: A pair of 'alala foraging in the misty Hawaiian forest.)

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