Thanks to the association with a certain video game franchise, cardinals have gained something of a reputation as "angry birds", aggressively defending their territory.
But is this reputation fair and accurate? Are cardinals territorial, and if so, is their fierce defensive nature present all year round? We’ll take a look at whether cardinals are aggressive birds, so keep reading if you’re interested in finding out.
During the breeding season, Northern cardinals are highly protective of their nest site, mate, and any eggs or young. They chase off any threat to their territory, whether it’s another cardinal or other bird species. Once breeding ends, this feisty nature fades, and they form loose foraging flocks.
The defensive displays of a Northern cardinal can be quite explosive if an intruder strays into their patch at the wrong time, their crimson coloring adding to their fiery temperament.
Northern Cardinals are generally placid and sociable birds, until the breeding season, when they become highly territorial
Male Northern cardinals have even been observed in long-lasting stand-offs with their own reflections in windows, considering the ‘other bird’ a threat to their territory and embarking on an animated attempt to drive the rival off.
However, once the mating season is over and any young have successfully fledged and gained independence, Northern cardinals revert to a more passive, even sociable nature, forming larger foraging flocks to maximize their chances of finding food through the winter months.
Keep reading to find out more about the seemingly "split personality" of these striking songbirds, which seem to be able to seamlessly switch between being fierce defenders of territory to sociable flock members.
Male Cardinals are highly protective of their mate during the breeding season
Northern cardinals are notorious defenders of their nest site during the breeding period, which lasts from April to September each year. During these months, they will aggressively see off any threat to their mate, and any chicks or unhatched eggs. They are particularly vigilant against the presence of other male cardinals, although they are equally intolerant of unwanted visitors of any other species.
Breeding cardinals guard their nest site and will not tolerate the presence of other male cardinals on their patch. They become particularly vocal, and will fly at any intruding birds, pecking and biting at them to drive them away. Females may also join in, attempting to ensure their territory remains safe and uncontested so they can successfully raise their young.
Male Cardinal perched on a branch
The peak time for Northern cardinals to display territorial behavior is just ahead of and throughout the breeding season. In the early stages of nest site selection, males may exhibit increasingly aggressive behavior, attempting to drive off any competition from an area in which they are attempting to claim as their territory. Several males may compete for the area with the most suitable nesting spots, nearest to food sources.
Once a nest has been built, males and females will both engage in territorial displays, driving off any encroachment on their patch which they see as a potential threat to their eggs or young. Males will noisily defend brooding females from other male cardinals and will remain vigilant against any other threats from predators.
Outside of this period, which typically lasts from late March to September, Northern cardinals are generally placid, sociable birds. An exception might be in midwinter, when competition for food at bird feeders may be observed, with cardinals’ feisty side temporarily resurfacing when food availability may be lower than usual.
Male Cardinal feeding a female seeds
During the breeding season, cardinals are particularly territorial about the presence of other male cardinals near their nest site, and will actively drive them away with aggressive displays, flying at their rivals to scare them off.
Once the nesting period is over, their fierce and intolerant streak subsides, and they form feeding groups with other cardinals, which helps them to source food sites. Foraging together brings safety against predators, as well as improving their chances of finding food.
While it is the scarlet male Northern cardinal that has the main reputation as one of nature’s angriest birds, female Cardinals can be just as feisty during the breeding season and will join in with any required attempt to drive away intruders that threaten their nest sites.
Female Cardinals can be just as territorial as males during the breeding season
Cardinals are generally tolerant of human company and are reasonably trusting towards the presence of people, possibly associating them with the provision of food.
Nest sites are chosen that may be in close proximity to humans, and cardinals can learn to distinguish between individuals they have encountered before and those who might pose a threat.
If a human disturbs a nesting cardinal, there is every chance that they would see for themselves just how protective these birds can be, as they react to any potential predator with everything they have in their power to ensure the survival of their mate and their young.
Generally speaking, cardinals observed at bird feeders are calm and sociable and feed alongside other cardinals and different bird species without any aggressive interactions. One exception may be in harsh winter conditions when there is potentially more competition for limited food.
Such interactions are typically short-lived and largely limited to the northern extremes of their range, where colder temperatures increase cardinals’ reliance on food supplied by humans.
The survival instinct kicks in, and hungry cardinals will fight for food, with their head thrust forward and wings spread wide.
Male Northern Cardinal being territorial over a feeder with a female Red-winged Blackbird
Well-stocked feeders with plenty of available choices, spaced out across as wide an area as possible in your backyard, will ease any potential conflict between hungry, foraging cardinals.
Cardinals are ground feeders and will eat oats, buckwheat, breadcrumbs, and millet, as well as sunflower seeds and suet.
Feeding stations that offer a large foraging space, alongside feeder types that are not favored by cardinals (upright tube feeders with shorter perches, for example), will ensure all garden visitors have a chance to feed with as little stress as possible.
Cardinal sharing a feeder with American Goldfinches
If other birds pose a threat to a northern cardinal’s nesting spot, its young or its mate, then it will aggressively attempt to scare them off. Noisily posturing, flying at the potential intruder, and aggressively pecking at them, is usually enough for the encroaching bird to retreat.
Threats to nests, e.g., from larger birds of prey, are defended by feisty cardinals in the same way, creating a hostile environment and ensuring the safety of their eggs or young.
While most cardinals are quite non-confrontational outside of the breeding season, occasions may arise around bird feeders in winter, particularly when harsh conditions make it more difficult to forage for food naturally.
Hungry cardinals may jostle for position, claiming the top spot in the pecking order using aggressive pecking and flapping of wings to secure their claim.
Northern Cardinal in flight
Northern cardinals will enter into a fearless defense of their nesting territory when they sense it is under threat, and will stop at nothing to ensure their mate and chicks are safe.
As fairly lightweight birds, it is not unheard of for fights to end with the fatality of one of the pair engaged in the clashes, although in the majority of cases, the intruder is forced to retreat before it reaches this point.
Particularly feisty cardinals will take issue with what they think is an intruding bird, but in reality, is their own reflection in a glass window pane.
In such instances, the protective bird may repeatedly fly at the window in an eternally fruitless bid to drive off the persistent aggressor without realizing that it’s, in fact, itself that it is attempting to scare away.
Fatalities from collisions with windows do cause a number of deaths among both male and female cardinals.
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