The finch, a bird that lives in colonies and defends its nest against other species. They are territorial!
The Finch is a smallish songbird with an unusually large head for its size. Finches live in colonies and their nests are typically located on the ground or in trees near water.
The most commonly found species of finches feed mainly on seeds, fruits, plant buds and insects while some have evolved to eat only nectar (such as the Purple-throated Fruitcrow). All finches lay two eggs at a time which they incubate for about 12 days until hatching.
Finches form monogamous pairs during breeding season but will also pair up with another individual if one mate dies or disappears from the colony; replacing a mate is a common occurrence in finch species.
Finches are highly territorial during breeding season and will aggressively defend their nests from intruders (even other finch species).
Finches also tend to be aggressive towards other birds that get too close to their nests, even ones they may not have seen before.
The importance of territory for birds
While some suggest that there is a direct connection between the amount of territory an animal has and its reproductive success, others believe that it is more likely that territoriality evolved as a byproduct.
It’s worth mentioning, however, that birds, in general, are quite territorial especially when it comes to their nests; this behavior most likely evolved to protect their eggs and chicks.
Territoriality has been linked with reproductive success, in that female birds who maintain large amounts of territory tend to lay more eggs than those who are less territorial.
While there is no definitive reason for this, one possible explanation could be that as the number of nest intruders increases, so does the risk of predation.
The more nest intruders there are, the greater the chance that a predator will be successful and take one or more eggs.
However, this doesn’t mean that all territorial animals have greater reproductive success; this is only applicable to sexually mature birds who maintain a territory adjacent to a nesting site throughout the breeding season.
Different types of territories
Nesting territories are the nest and the surrounding area used by a single pair of birds. It is what they will fight for when an intruder approaches their nest.
These territories vary in size depending on the species; smaller birds tend to have larger nesting areas than bigger birds, but there are exceptions.
Nesting territories are characterized by the following:
- nest sites (the place where an individual breeds)
- a mating pair or single parent (usually male) guarding the site and their offspring. The breeding pair is usually located in the center of the territory, protecting it against intruders. Females will defend young chicks but only if they are not able to fly.
- a marked boundary such as a wall or cliff (common with some species of bird)
- the surrounding area, occupied by subordinate males known as satellite males who will defend the territory against other intruders. If one of the breeding males dies, then the dominant male in the territory will try to impregnate the remaining female.
- a site of communal roosting (as in the case with starlings, where they roost together each night).
Feeding territories are characterized by the following:
- a specific food source
- guard birds who defend the territory against intruders and gather food for the rest of the colony.
Depending on the species, feeding territories are located either in areas where food is abundant (such as where there is a large supply of insects or seeds) or it may be limited to specific portions of land.
The latter is common with birds living near human habitation, such as sparrows and pigeons who will defend the specific area they feed on (such as a sidewalk or rooftop) from other birds.
These are characterized by:
- definitive boundaries, formed by walls, cliffs, trees, and rocks
- a communal roost occupied each day holding dozens of individuals. There may be more individual birds in the territory, they don’t all roost every night.
The reasons for these territories are debated; some believe that the reason is to protect against predators and others say that it is to reduce competition between birds who do not have enough food or suitable nesting sites.
Defending And Mating Territories
These are not always clearly defined, and they may overlap with feeding and nesting territories.
Defending territories include breeding males who protect the nest (see above) as well as females when defending young chicks. Mating territories refer to areas where an individual or group pairs up. Males will fight for these areas in order to attract a female to mate with.
Males will also defend their mating territories in order to keep other males away from the female.
When it comes to territory, there are two main stances: territoriality and semi-territoriality.
Territorial animals exhibit aggressive behavior towards intruders, defending their territory (which is essential for breeding and survival) while semi-territorial animals exhibit aggressive behavior against intruders, but do not defend their territory.
So what does this mean for finches?
Finches are territorial birds who exhibit highly aggressive behavior towards other birds of the same species or even different species when they encounter them on their nesting sites (or feeding areas or roosting sites).
For instance, the territory of a house finch is typically about 900 square meters, while that of a tree finch is about 2.5 hectares.
Many defend their territories in different ways; some species will build nests with strong walls to protect against predators (such as sparrows) while others will use twigs or rocks to build their fortresses.
In addition, other species will lay several eggs at a time and scatter them around the nest so that if one is stolen, the rest of the brood is not lost. Some birds also attack intruders with a kind of hissing sound which acts as a warning.