Caracara: breeding success

We are very interested in the variation of breeding success of the different caracara pairs. To monitor breeding success, we record matings and nest buidling behaviour, we visit each nest regularly to check the presence of eggs and chicks, and we follow the development of the chicks until fledging.

Caracara's mating

Caracara's mating

Most caracara's pairs produce two eggs, and they are usually able to raise both chicks until fledging, although there is some variation between pairs. Some very successful pairs are able to consistently raise three chicks seson after season.

Two chick of different size

Two chicks of very different size in the same

An interesting aspect of Sea Lion Island caracaras is their constantly high breeding success notwithstanding the variation in the status of their prey populations. This is probably due to caracaras very flexible diet, that permit them to change prey and food items depending on availability. Even in potentially bad seasons, most pairs are able to raise to fledging one or more chicks. This is in sharp contrast with other birds nesting at Sea Lion Island. For example, the skuas, that also feed on local marine bird eggs and chicks, can be strongly affected by resource availability (see link).

Caracara feeding two chicks

Caracara feeding two chicks

Caracaras actively defend their nests. Although there is a lot variation in the aggressiveness of different pairs, it is important to try to avoid as much as possible to approach nests at close distance, to reduce stress for the birds, and the risk for humans, caracaras can hit heads very hard ! Therefore, we visit each nest just once per week and very briefly. Until now, we had no case of nest abandoment due to our visits.

Caracara's territorial reaction

Aggressive reaction of a nesting pair


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