Behavior

Walking, Climbing, Hopping, Etc.

Usually walk on ground rather than hop, run, or fly. Tail not bobbed up and down as waterthrushes do, but is often pumped in a wave-like fashion as Hermit Thrushes (Catharus guttatus) do (Forbush 1929). Often, tail is held high with wings drooping below it.

Flight

Low, firm, and steady. Maneuvers quickly around tree trunks and swoops from ground level to a canopy song perch.

Preening, Head-Scratching, Stretching, Bathing, Anting, Sunbathing, Etc.

Not known to ant. Head scratch under the wing in the wild, in captivity, and as nestlings (Burtt and Hailman 1978). This indirect method of scratching is thought to be an adaptation for keeping the wings clean in ground-dwelling warblers that primarily walk rather than hop or run. Described as “fond of bathing” (Forbush 1929), but no additional information given. Roosting, stretching, and sunbathing behaviors not described.

Daily Time Budget

Not reported in detail. In the breeding season, males sing actively from dawn to mid-morning (10:00–11:00; Lein 1980) and early evening to dusk (Bent 1953). Proportion of time spent in various behaviors is not known.

Physical Interactions

As boundaries of territories are being established, encounters between males are vigorous and prolonged (Weeden and Falls 1959). Chasing and vocalizing are primary methods used to ward off intruders. Physical contact is rare, and no injuries reported (Hann 1937, Weeden and Falls 1959).

Communicative Interactions

No known records of appeasement displays. Threat displays not described.

Individual Distance

While Ovenbirds are thought to be territorial on the wintering grounds (Faaborg and Arendt 1984), there is no information available on individual spacing. During the breeding season, boundaries of clusters of territories are known to be separated by 18.3 m (Stenger and Falls 1959).

Territoriality

In spring, territories are established by males immediately upon arrival on the breeding grounds. These are used for courtship, mating, nesting, and feeding for adults and young (Smith and Shugart 1987). Ovenbirds defend and maintain territories primarily through song. Singing is frequent and aggressive during the establishment period, but declines after pairs have formed (Hann 1937, Lein 1981, Gibbs 1988; see Songs and Calls, Phenology). During the nestling period and after young have left the nest, a few call notes from a territory holder are sufficient to drive an intruder away (Weeden and Falls 1959). Once established, territories persist throughout the breeding season except for minor shifts (Hann 1937, Weeden and Falls 1959). Territory size may vary during the breeding season. Territories are larger when food is being gathered for the young and smaller during the copulation period (Stenger and Falls 1959).

Many studies of territory size and density have been conducted across the range of the Ovenbird; these show considerable variation. Within a locality, density is often lower in fragmented forests. Territory size has been found to be inversely proportional with food supply, diminishing as prey becomes more abundant (Stenger 1958, Smith and Shugart 1987). During a spruce budworm (Choristoneura fumiferana) outbreak in Algonquin Park, Ontario, territory size decreased from 0.827 ha in a non-budworm year to 0.479 ha (Zach and Falls 1975).

In Missouri, a color-banding study showed territory size was similar in fragmented (2.58 ha ± 0.36 SE, n = 107) and contiguous (2.89 ± 0.11 ha, n = 116) landscapes, but density was significantly less in fragmented (1.6 ± 0.41 /10 ha) than contiguous (2.2 ± 0.32 /10 ha) landscapes (Porneluzi and Faaborg 1999). Earlier studies in Missouri reported territory size ranging from 0.88 to 1.40 ha (Wenny 1989) and average territory densities of 1.4 / 10 ha in small forest fragments and 2.2 /10 ha in large fragments (Gibbs and Faaborg 1990).

Similar results have been measured in a color-banding and telemetry study in central Saskatchewan (Mazerolle and Hobson 2004). Territory size was similar in fragmented and contiguous forest (1.42 ha ± 0.16 SE, n = 22 and 1.29 ha ± 0.15 SE, n = 13, respectively) but territory overlap was greater in fragments (34%) than in contiguous forest (20%). Density was significantly greater in contiguous forest (10.4 ± 0.9 / 10 ha) than fragments (5.3 ± 0.5 / 10 ha), suggesting more unused area in fragments. Territory size and overlap were not related to arthropod biomass, but larger and older males had larger territories. This study also emphasized that their use of radio telemetry showed that studies based on observations of singing males likely underestimate the area used by Ovenbirds, in their case by a factor of two (Mazerolle and Hobson 2004).

In Pennsylvania, a before-after controlled experiment showed no effect of adding lime to counteract acid deposition on mean territory size (0.864 ha ± 0.068 SE, n = 42) or density (0.292 ± 0.067 SE territories/ha, n = 42), though an increase was suggested in year three (Pabian and Brittingham 2007).

In Vermont, territories were significantly larger near the edge (0.53 ha ± 0.03 SD, n = 7) than the interior (0.39 ha ± 0.03 SE, n = 14) of fragments (Ortega and Capen 1999). This study also measured significantly lower densities in the edge (6.2 ± 0.8 / 10 ha) than the interior (9.9 ± 0.1 / 10 ha).

In n. Wisconsin, mean density was 3.1 / 10 ha (Flaspoler et al. 2001). In New Jersey, density averaged 1.4 / 10 ha in fragments and 7.7 / 10 ha in extensive forest (Wander 1985). In New Hampshire, density measured 12. 5 ± 4.0 SD / 10 ha (Holmes and Sherry 2001). Villard et al. (1993) measured density of 2.3 / 10 ha in fragments in Ontario and 4.5 / 10 ha in extensive forest in Quebec. In s. Ontario, density ranged from 0.33 / 10 ha on smaller fragments to 8.3 / 10 ha on the largest fragment (Burke and Nol 1998). Territory size in Michigan reported from 0.20 to 1.80 ha (Hann 1937), and in Ontario, from 0.61 to 1.60 ha (Stenger 1958). Such regional variation is expected because Ovenbirds breed in forests that vary in vegetation structure and corresponding invertebrate abundance.

Through removal experiments, Bayne and Hobson (2001) demonstrated that non-territorial floater males were present in contiguous forest, but rare in fragments in Saskatchewan.

Interspecific Territoriality. Not well described. In n.-central Missouri, Kentucky Warblers and Ovenbirds have been heard counter-singing during territory establishment (MVH), and Kentucky Warblers were caught in mist nets when the Ovenbird song was played (J. Faaborg, pers. comm.). In Algonquin Park, Ontario, the feeding ecology and food niche of the Ovenbird showed little overlap with those of other species, and interspecific territoriality was not observed (Stenger 1958).

Winter Territoriality. In Veracruz, Mexico, individuals of both sexes have been observed defending territories (Rappole and Warner 1980; Brown and Sherry 2008a), and mist netting studies in the Guanica Forest, Puerto Rico, suggest that Ovenbirds are territorial on the wintering grounds (Faaborg and Arendt 1984). Four-year telemetry study in Jamaica found that 83-92% of the population showed sedentary behavior with considerable overlap between solitary feeding and roosting home ranges (Brown and Sherry 2008a). There was little overlap in use of the core area (30% of observations) of home range. Most individuals also roosted within their core foraging area (Brown and Sherry 2008b). The remaining 8 – 17% of the individuals in the population were floaters showing a wide range of movement patterns. Some individuals were floaters in multiple winters and the tendency to be sedentary or floater did not differ between age and sex classes (Brown and Sherry 2008a). Territory defense occurred mainly during the early part of the winter season and through chance encounters and the birds generally showed inconspicuous “skulking” behavior and rarely vocalized.

Dominance Hierarchies. No evidence available.

All information in this section, unless cited otherwise, derived from Hann (1937). Chiefly monogamous, but polyandry (Hann 1940, King et al. 2000) and polygyny recorded. Detailed information on sex ratios unavailable.

Pair Bond

Courting performances and pre- and post-copulatory displays not described. Copulation takes place during nest building and egg laying periods on the ground, and occasionally, in trees. Ground copulations, while complaisant for both sexes, appear to be a struggle. When the male dismounts he usually flies to a nearby perch and the female shakes as if smoothing her feathers and then proceeds with daily activities. During copulation from a perch in a tree, the male mounts and dismounts quickly and may perch on the female's crest prior to copulation.

The pair bond is formed on the breeding ground and is terminated when the young fledge. The same pair may mate in successive years. In instances where nests are deserted or destroyed, the pair may renest together or find new mates and renest.

Extra-Pair Mating Behavior

Hann (1937) observed 2 nesting females copulating with neighboring males. In one case, the female solicited the copulation within a neighboring male's territory. Her mate attempted to follow her but was driven out by the male territory holder. In the second case, a neighboring male slipped into the territory, copulated with the female, and was then driven off by her mate.

Degree Of Sociality

Degree of sociality during migration unknown. Available information suggests solitary behavior on the wintering grounds (see Behavior: winter territoriality). Some evidence that conspecific attraction may lead to clusters of territories (Baker 1985, Wander 1985, Wenny 1989). Territory aggregation was linked to aggregation of ground cover and percent deciduous cover at the scale of 250 m but was not explained by habitat at the scale of 450 and 550 m (Bourque and Desrochers 2006).

Play

Unknown in adults. For young, see Breeding: immature stage..

Kinds Of Predators, Manner Of Predation

Egg predators include various snakes, Blue Jays (Cyanocitta cristata), and Brown-headed Cowbirds (Molothrus ater). Predators on eggs and young are red squirrel (Tamiasciurus hudsonicus), eastern gray squirrel (Sciurus carolinensis), raccoon (Procyon lotor), striped skunk (Mephitis mephitis), and weasels (Mustela sp.). Known predators on young and adults include Barred Owls (Strix varia) and Broad-winged Hawks (Buteo platypterus; Hann 1937, Bent 1953). Other suspected but unconfirmed predators include American Crow (Corvus brachyrhynchos), Common Grackle (Quiscalus quiscula), opossum (Didelphis virginiana), red fox (Vulpes vulpes), and domestic cat (Felis domesticus; Gates and Gysel 1978).

In a radiotelemetry study, King et al. (2006) note that nearly half of the dead fledglings (n=12) were recovered from chipmunk (Tamias striatus) burrows and several others were recovered from elevated perches, suggesting predation by Accipiter spp.

Response To Predators

Males fly at females and/or give an alarm call as a warning of approaching danger (Hann 1937). Male and female observed chasing predators with their mouths open and flying at predators (Hann 1937). Hann (1937) also described his hand being pecked by a female while examining her nest. King and DeGraff (2006) report video observations of adults defending their nest six times against mice (Peromyscus leucopus) and once against eastern chipmunk (Tamias striatus) within one week. The adult rushed at the predator with wings spread but the nest was ultimately abandoned and the nestlings consumed by the mouse.

When predators approach the nest the female sits tight until the last moment, then attempts to lead intruder away by feigning injury (described by Hann 1937). Female emits the seet vocalization during this display (Lein 1980). Behaviors, if any, exhibited by male while protecting brood not known.