Males are brilliant red. Females are warm brown with red accents on wings, crest, and tail. That colour difference is the most obvious distinction, but males and females also differ in behaviour, singing patterns, and parenting roles.
Side-by-Side Comparison
| Feature | Male | Female |
|---|---|---|
| Body colour | Bright red all over | Warm brown with reddish hints |
| Face mask | Bold black mask around beak and eyes | Faint grey mask, much less prominent |
| Crest | Red, slightly larger | Reddish-brown, slightly smaller |
| Beak | Bright orange-red | Orange-red, same shape |
| Size | Slightly larger on average | Slightly smaller |
| Weight | 42-48g | 40-45g |
| Length | 21-23cm | 21-23cm |
Behaviour Differences
| Behaviour | Male | Female |
|---|---|---|
| Singing | Loud, frequent, especially in spring | Also sings - unusual among songbirds, songs can be longer and more complex |
| Territory | Fiercely territorial, attacks reflections in windows | Defends nest area but less aggressive overall |
| Visibility | Conspicuous - perches in open, sings from treetops | More discreet, stays in dense cover |
| Nest building | Brings nesting materials | Builds the actual nest |
| Incubation | Feeds the female while she sits on eggs | Incubates the eggs (12-13 days) |
| Feeding chicks | Feeds chicks, often takes over when female starts second brood | Primary feeder in early stages |
Why Males Are Red
The red colour comes from carotenoid pigments in their diet - mainly from red berries containing rhodoxanthin. A male that eats more pigment-rich food is brighter red. Females prefer the brightest males because intense colour signals good health and strong foraging ability.
Females are brown for the opposite reason - camouflage. A brown bird sitting on a nest in a shrub is nearly invisible to predators. Being bright red on a nest would be a death sentence.
Both Sexes Sing
Female cardinals sing, which is rare among North American songbirds. Their songs can actually be more complex and longer than the male’s. Males sing primarily to defend territory and attract mates. Females sing to communicate with their partner, signal readiness to breed, and sometimes to defend the nest.
Mated pairs also perform duets - coordinated songs that strengthen their bond and warn rivals.
Cardinal Vocalisations
| Call type | Who uses it | Purpose |
|---|---|---|
| Territorial song | Mostly male | Warns rival males away |
| Mating song | Both | Attracts mate, signals readiness |
| Duet | Mated pairs | Strengthens pair bond |
| Chip call | Both | General contact, mild alarm |
| Sharp metallic call | Both | Predator alert |
Window Attacks
Both sexes attack their reflection in windows, mistaking it for a rival. Males do this more often and more aggressively during breeding season. The bird sees a “rival” that will not back down and keeps fighting. Window decals or external screens solve the problem.
Male cardinals are bright red to attract mates. Females are brown to hide on the nest. Both sing, both feed chicks, and both defend territory. The colour is different, but the partnership is equal.
