Northern Cardinal Cardinalis cardinalis
Version: 2.0 — Published February 12, 2021
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Demography and Populations
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Measures of Breeding Activity
Age at First Breeding; Intervals Between Breeding
Males and females breed their first spring after fledging (46, 294). Time between date of young fledging and date of first egg in the next nest ranges from 5–33 d (conservative estimates; 293; D. Scott, personal communication). Intervals are longer when more than 1 young fledges, potentially because the female feeds the fledglings for a longer period (293, 67; see Breeding: Parental Care). If the nest is destroyed after more than 1 egg has been laid, the interval to renesting does not appear to vary with the stage of the nest when it failed (first egg is laid an average of 5.53 d ± 1.36 SD after failure of previous nest; 302). In two cases in which a nest was destroyed within hours of the laying of the first egg, an egg was discovered in a replacement nest 3 days later. Re-laying intervals in southern Ontario are longer and more variable in April and May than in early June, after which they increase slightly; renesting intervals are also longer with colder-than-average temperatures (302).
Typical clutches include 2–3 eggs; range 1–5 eggs, though records of single eggs questionable given possibility of undetected predation (100, 277, 40); 3 eggs is the median and mode in most locations (311), though local variation occurs. See also Breeding: Eggs.
Mean clutch size appears to be slightly higher closer to the center of the continental North America than on the East coast, and lower in Bermuda than on most of the U.S. mainland (311). Reports differ on whether clutch size varies across the breeding season; clutch sizes decrease as the breeding season progresses in southern Indiana and northern Arkansas (67, 326), but there is no significant correlation between clutch size and laying date in southern Ontario or southwestern Ohio (293, 266).
Annual and Lifetime Reproductive Success
See Appendix 2. Annual reproductive success in central Ohio was 2.1 ± 0.09 fledglings per female (range 0–7, n = 306 females) (54). In urban and rural forests in central Ohio, average 1.8 young fledged/successful clutch (cowbird eggs not removed; maximum number of fledglings = 3; n = 461 clutches) (54).
Among successful clutches in southern Indiana (nests from which Brown-headed Cowbird eggs were removed), an average of 2.0 young fledged/clutch (n = 10 clutches) on an urban university campus, and 2.3 young fledged/clutch (n = 6 clutches) in successional field habitat with shrubby borders (294).
Lifetime reproductive success is not known.
Number of Broods Normally Reared per Season
Over 3 years (2005–2007) in rural and urban riparian woodlands in central Ohio, females had 0.76 ± 0.75 SD successful nests per year (range 0–3, n = 306 females) (DPS, A. Rodewald, unpublished data). In a southern Ontario population, ≥ 1 cardinals fledged from 1.67 nests/pair ± 0.82 SD (range 1–3, n = 6 pairs) in 1955, and from 0.71 nest/pair ± 0.76 SD (range 0–2, n = 7 pairs) in 1956 (293). Successful fledging of young reported in up to 4 nests/pair/season (303, 99).
Proportion of Total Females That Successfully Rear at Least One Brood to Nest-Leaving or Independence
In central Ohio (2005–2007), in 306 annual female nesting histories, ~40% produced no successful nests, 45% produced 1 successful nest, 13% produced 2 successful nests, and 2% produced 3 successful nests in a given year (DPS, A. Rodewald, unpublished data). In a southern Ontario population, at least one nest fledged young for 6 of 6 females in 1955 and 4 of 7 females in 1956 (293).
Life Span and Survivorship
Oldest reported wild female was at least 15 yr 9 mo (327); oldest reported wild male at least 13 yr 2 mo (328). Of 85 cardinals recaptured or found dead in a 12-year banding study of 1,621 individuals, “many” were recaptured or found dead between the ages of 2 years and 3 years (100). Thirty birds were known to have survived for at least 3–6 years: 16 birds were last seen in year 3; 9 birds in year 4; 3 birds in year 5; and 2 birds in year 6 (100).
Eggs and Nestlings
See Appendix 2. In central Iowa, 14% of eggs that were in the nest at hatching time failed to hatch (292). In southern Indiana, mean mortality rate for eggs was 5.1%/day during incubation (n = 212 eggs); mean mortality rate for nestlings was 5.2%/day (n = 108 nestlings; 67). Survivorship curves were close to linear for both eggs and nestlings, indicating a nearly constant daily rate of loss throughout the incubation and nestling periods. Higher success rate among later nests than earlier nests appears to be common (67, 43, 54). Kinser (67) hypothesized that this difference might be due to lowered predation by snakes later in summer; reduced brood parasitism by cowbirds (293, 38) may also increase the success of later nests. Amur honeysuckle, a preferred nesting substrate, provides early-season cover due to early leaf emergence relative to native shrubs, but early-season nests in honeysuckle have lower survival than nests in native species or later nests in honeysuckle (52), perhaps due to nest predators focusing their searches in honeysuckle during the early breeding season. However, 2-ha patches of urban forest from which honeysuckle was experimentally removed had higher levels of nest predation over the next 4–5 breeding seasons than did control urban sites where honeysuckle was left in place, perhaps due to a lag in replacement of the removed honeysuckle with more protective nesting habitat (cardinals included in a combined analysis of 7 understory-nesting species with cardinal nests accounting for 62.6% of nests followed; 329).
Fledglings and Immature Birds
Survivorship of fledged young to 28 days after fledging was 80% in southern Ontario (based on direct observation of fledged young; 208). Of birds banded as nestlings or young fledglings, 21% were found locally in early May of the following year; others may have dispersed farther (208). In central Ohio, fledgling survival to 71 days was 44%, as estimated with radio telemetry (325).
Approximately 65% of breeding birds in a southern Ontario population returned to the same study area in the following breeding season (46). In central Ohio, 59% of breeding males and 57% of breeding females were observed in the subsequent breeding season (54). Apparent annual survival estimates for adult cardinals ranged from 50.5% ± 10.3 SE to 78.3% ± 7.6 SE across 14 forested study sites spanning an urban to rural landscape (304). For first-year breeders, 49% (23/47) were found in a North Carolina study area during the next breeding season, as were 75% (12/16) of second-year breeders (251). An annual survival rate of 60% ± 6 SE was calculated for cardinals in Maryland, based on a mark-recapture study with analysis permitting heterogeneous time-specific capture probabilities; the data best fit a modified Jolly-Seber model that allowed variation in capture probability, but assumed constant survival probability and equal survival for newly and previously banded individuals (330).
Disease and Body Parasites
Northern Cardinal has high rates of infection and high rates of survival for mosquito-borne diseases. Their use of shrub habitat at edges of forests and fields, in swamps, in riparian areas, and in plantings around residences exposes them to high encounter rates with mosquitoes. Data from genetic analyses of mosquito blood meals indicate that cardinals are among the birds most preferred by mosquito vector species (e.g., 331, 332). Cardinals play a relatively minor role as amplifying hosts for some mosquito-transmitted viruses.
Antibodies to eastern, western, and/or St. Louis encephalitis virus were detected in 86% [24 of 28] of wild-caught birds in Alabama; 333); based on mosquito feeding preferences and correlational data, Northern Cardinal may play a secondary role in amplifying eastern equine encephalitis in the northeastern and southern United States (334, 335, 336, 60). For West Nile Virus (WNV), antibodies have been detected in 2–69% of wild-caught cardinals (samples of 13–506 cardinals tested), with higher levels in suburban than in rural areas; Northern Cardinal may be a useful WNV sentinel species (337, 338, 339, 340). West Nile Virus mortality estimates of 11–35% in laboratory and field studies, possibly up to 50% in stressed individuals (338, 341, 59). West Nile Virus antibodies detected in 20% of 92 hatch-year birds and 30% of 40 adults tested in August 2002 in Slidell, Louisiana (N. Komar, unpublished data); lower percentages of hatch-year birds with antibodies could indicate lower infection rates or lower survival rates. Higher percentage of females with WNV antibodies in one study (342); higher percentage of males in another (N. Komar, unpublished data); no difference by sex in two others (343, 59). The Northern Cardinal may serve as important amplifying hosts for WNV in some regions, but are relatively unimportant in most regions (338, 58, 341, 344; A. M. Kilpatrick, personal communication). Breeding Bird Survey data from 10 states from 1994–2010 show no significant effect of WNV on cardinal populations (345).
Antibodies to Avipoxvirus, which can be spread by mosquitoes as well as by direct contact with infected birds, were found in 24 of 60 cardinals (40%) tested in Illinois (346). Inactive avian pox lesions were found on 1 of 51 cardinals tested in Hawaii, where pox virus lesions were more commonly found on other native and non-native species of birds tested (347).
Bacterial and Fungal Diseases
From U.S. Geological Survey (USGS) National Wildlife Health Center, unpublished data: Occasional lethal outbreaks of salmonellosis in cardinals, usually from contact with feces of infected birds at feeding stations; occasional lethal conjunctivitis (causal agent not specified), avian cholera, and aspergillosis. Antibodies to Mycoplasma gallisepticum, a causative agent of avian conjunctivitis, were found in 6 of 60 cardinals (10%) tested in Illinois (346); in the northeastern United States, higher numbers of cardinals were counted at feeders in areas with higher levels of infection in House Finches, suggesting that cardinals may be serving as a reservoir species that can transmit this bacterium to House Finches (348).
Percentage of 342 Northern Cardinals sampled in North America with each blood parasite (349): Plasmodium, the causal agent of avian malaria (28%), Haemoproteus (17%), Leucocytozoon (3%), and Trypanosoma (2%). In a survey of non-breeding cardinals in Mississippi, no evidence of Plasmodium infection observed (350). In a study mapping the distribution and diversity of Plasmodium and Parahaemoproteus among cardinal clades, DNA analyses of blood and/or tissue from 5–112 cardinals/clade revealed infection with one or both of these avian malaria parasites in cardinals from 5 of the 6 clades, at levels from 59.1–74.1% of individuals sampled (mean 67.4%, 351). Northern Cardinal was among the species found dead in an outbreak of respiratory trichomoniasis in Greene County, Ohio, 7 June–14 July 1983 (USGS National Wildlife Health Center, unpublished data). A Lankestrella-like coccidian was found in lung lesions of a cardinal in California with pneumonia (352).
Microfilarial nematodes were found in the blood of 5% of 342 cardinals sampled (349). Of proventricular parasitic nematodes, Dispharynx nasuta was found in 5 of 14 cardinals collected in central Florida (353); Tetrameres cardinalis was collected from a cardinal from Mexico (354). Oxyspiura petrowi and O. pusillae (nematode eye parasites) were each found in different single individuals among 20 cardinals collected in southern Louisiana (355).
Ectoparasites found on Northern Cardinal or in their nests include lice, flies, mites, and ticks. Lice include blood-sucking Myrsidea incerta and feather-eating Philopterus subfalvescens (356). Analgopsis and Knemidocoptes mites feed on cardinal feathers and skin on legs, respectively (356, USGS National Wildlife Health Center unpublished data). Hundreds to thousands of northern fowl mites (Ornithonyssus sylviarum) have been found in cardinal nests (357); the mite Neharpyrhynchoides novoplumaris is also reported from cardinals (358). Blood-sucking ticks (Amblyomma americanum (lone star tick), Amblyomma maculatum, Dermacentor variabilis, Haemaphysalis leporispalustris, Ixodes affinis, Ixodes dentatus (infected with Borrelia miyamotoi, a causative agent of relapsing fever), Ixodes scapularis, and Ixodes minor), and blood-sucking hippoboscid flies (Ornithomyia anchineuria) have been found on cardinals (356, 359, 360, 361). Five species of ticks were found on cardinals on a single Georgia barrier island (359). The Lyme disease spirochete Borrelia burgdorferi has been isolated from cardinal blood (362); in lab tests, wild-caught cardinals were able to infect larval Ixodes scapularis ticks with the B. burgdorferi spirochete (363). Protocalliphora blowflies, whose larvae suck blood of nestlings, and biting midges (e.g., Culicoides travisi) are found in nests (279, 357). Limited quantitative data are available on the incidence and severity of ectoparasite infestations.
Loss of Head Feathers
Individual Northern Cardinals lacking some or all head feathers are periodically reported; e.g., 7 of 1,621 cardinals mist-netted in Tennessee (100, ). Feather loss may be a delayed response to injury, but the cause is typically unknown; the skin of the head usually appears normal and not to be causing discomfort, and head feathers regrow at the next molt. Assessment of skin scrapings from a single bald male in Mississippi showed significant fungal hypha content, species unknown (JMJ).
Causes of Mortality
From a population perspective, the relative importance of exposure, predation, diseases and parasites, egg destruction by cowbirds, and interspecific and intraspecific competition are not known. See Behavior: Predation, Breeding: Brood Parasitism, Life Span and Survivorship, Disease and Body Parasites, and Conservation and Management: Effects of Human Activity (Pesticides and Other Contaminants/Toxics and Collisions With Stationary/Moving Structures or Objects).
Population Spatial Metrics
Defended territory sizes during breeding season range from 0.21 to 2.60 ha (mean 0.93–1.50) across data from southern Indiana (n = 47 territories; 67), southwestern Ohio (n = 122 territories; 266), eastern Tennessee (n = 20 territories; 211), and southern Arizona (n = 4 territories; 135).
Home Range Size
Breeding-season home ranges of adult males varied from a mean of 1.2 ha ± 0.16 SE (range 0.5–2.3, n = 10 males) in a dense population in western Tennessee, to a mean of 18.8 ha ± 1.38 SE (range 11.0–23.2, n = 10 males) in a sparse population in southern Ontario, where most individuals had no conspecific neighbors (191). Winter home ranges in central Kentucky, measured by a similar maximum polygon method, had a mean size of 21.2 ha (male mean 19.9, n = 4 males; female mean 23.1, n = 3 females); limited observation time may have caused underestimates of home range size (267). Over the course of the winter, cardinals may move back and forth between feeding stations up to 2.1 km apart, and up to 4.5 km in one direction (214, JMJ).
Natal home ranges of 20 birds in central Ohio, as determined from radiotelemetry, from 0–71 days post-fledging and before dispersal, varied based on estimation using 95% kernel-density estimates (2.33 ha ± 0.32 SE; range 0.43–6.75 ha) vs. 95% minimum convex polygon (0.93 ha ± 0.13 SE; range 0.18–2.74 ha) (210).
Using data from the North American Breeding Bird Survey (BBS), the Northern Cardinal population was estimated at 110,000,000 individuals for the United States and Canada from 2005–2014 (364). Point-count abundance data collected by breeding bird atlas projects estimated populations at 2,100,000 individuals (95% CI: 2,060,000–2,140,000) in Ohio from 2007–2011 (365), 1,400,000 birds (95% CI: 1,340,000–1,470,000) in Pennsylvania from 2004–2009 (366), and 500,000 individuals in Ontario from 2001–2005 (145).
During the breeding period, BBS data (1982–1991; 367) indicated that abundance on survey routes (each route is 24.5 miles long and includes 50 stops, ~0.5 miles apart, with a 3-minute count of birds seen or heard at each stop) was highest in southeastern states, particularly Louisiana (59.2 birds/route, n = 34 routes) and Mississippi (49.0 birds/route, n = 29 routes). In the Northeast, lower abundances ranged from 0.5 bird/route (n = 10 routes) in Maine to 16.5 birds/route in Delaware (n = 10 routes). Numbers were relatively high in the Midwest (Ohio, 26.6 birds/route, n = 49 routes), but declined to the north and west, in Nebraska (2.3 birds/route, n = 23 routes) and South Dakota (0.04 birds/route, n = 2 routes). In Canada, abundance was low: Ontario, 1.3 birds/route (n = 23 routes); Quebec, 0.2 birds/route (n = 3 routes). In the Southwest, abundance was high in Texas (27.4 birds/route, n = 90 routes) and low in Arizona (2.6 birds/route, n = 10 routes).
In central Ohio, density (individuals/ha) was greater in urban forests than in rural forests during both the breeding period (2.6 ± 0.32 SE in urban vs. 1.5 ± 0.21 SE in rural) and the wintering period (2.0 ± 0.26 SE in urban vs. 0.5 ± 0.10 SE in rural) (201). In southeastern Arizona, studies using Breeding Bird Census and Winter Bird-Population Study methods reported densities of < 6–11 birds/km2 in undisturbed to moderately disturbed paloverde–saguaro (Cercidium–Carnegia gigantea) habitat, 10–40 birds/km2 in "exurban" and suburban habitat, and 5–42 birds/km2 in urban habitat (368). During winter, Emlen (192) estimated mean of 167 birds/km2 across several habitat types in southern Texas; see also Habitat.
Abundance has increased in northeastern United States and southeastern Canada during the past 200 years, likely owing to natural and human-induced changes in habitat (see Distribution: Historical Changes to the Distribution). Some range expansions have been the result of sudden population increases, possibly following drought years (369; see also 49). Banding records to 1962 indicate that dispersal distances were highest for the decade 1933–1942, and the proportion of cardinals moving from the 10-minute latitude and longitude block in which they were banded was highest for 1953–1962 (49). First appearances of cardinals in northward range expansions have often been reported in fall, winter, or spring (review in 214); northward and northeastward movements have been reported in late summer and fall (62). Local range contractions and expansions have been reported, but there is no evidence that population sizes or movements are cyclic over wide areas (49). “Pioneers” have appeared to be first-year birds responding to dispersal pressure at the periphery of their range (49).
Over a 45-year period (1970–2014), the population in United States and Canada increased by an estimated 17%, based on BBS data (364). BBS data (1966–2019) showed the Northern Cardinal population increasing in the United States by 0.1% per year (95% CI: 0.0, 0.2; n = 2,410 routes) and in Canada by 3.8% per year (95% CI: 3.1, 4.6; n = 139 routes) (Figure 4; 367). Generally speaking, populations increased in much of the northern half of the species' range, including the Midwest, and tended to decrease most in the southeastern United States. Increases were significant in the majority of individual regions; significant decreases occurred in the Central Hardwoods (–0.2% per year; 95% CI: –0.4 to 0.0; n = 151 routes), Southeastern Coastal Plain (–0.5% per year; 95% CI: –0.7 to –0.4; n = 306 routes), and Peninsular Florida (–0.4% per year; 95% CI: –0.8 to –0.1; n = 66 routes) (367). Christmas Bird Count data showed fluctuation in numbers with no clear overall change.
Population modeling of cardinals nesting in riparian forest sites in central Ohio (2005–2011) showed a negative population growth rate (lambda = 0.868 ± 0.01 CI, 55). Also see Conservation and Management: Effects of Human Activity: Alteration of Habitat.
Few data. Winter bird-feeding seems to have been important in northward range expansion, and body fat levels at northern edge of range appear just adequate to maintain thermal homeostasis (see Diet and Foraging: Metabolism and Temperature Regulation), but no data on population declines after severe winters. Brood parasitism by the Brown-headed Cowbird has mixed impacts (see Breeding: Brood Parasitism by Other Species). Predation is the major cause of nest failure (292; see Behavior: Predation). Small clutch sizes, rapid renesting and the ability to make many renesting attempts may be an adaptation to high rates of nest predation (43). Estimates of population growth rate (lambda) across urban and rural forests in central Ohio were consistently below 1, indicating sink populations in this study area, however, the contributions of nonforest habitats (e.g., residential neighborhoods) were unknown, as were the causes of negative growth rates (55).