Eastern Towhee - Timing of Major Life Events

Timing of Major Life Events

Arrival and departure of eastern towhees into summer breeding grounds varies with location. According to a literature review, eastern towhees typically arrive in New York in early April and leave by the middle of November. A review of eastern towhee in New Hampshire describes arrival in late April to May with the majority of eastern towhees departing in September. Further south, on the border of Tennessee and North Carolina, migration to high-elevation areas within the Great Smoky Mountains begins as early as March. Eastern towhees typically leave these sites in October. The Pipilo e. erythrophthalmus subspecies is the most migratory of the subspecies.

Breeding begins in spring and continues to late summer. Reports of eastern towhees nesting as early as late March in Florida and Georgia, in mid- to late April in some midwestern states, and as late as mid-May in northern New England were summarized in a literature review. Literature reviews also report nest construction by the female, which takes about 3 to 5 days. Egg laying typically occurs until August. For example, a review of eastern towhee in Indiana notes nesting from 15 April to 20 August. However, a literature review of eastern towhee in Florida included a report of an eastern towhee nest observed on 2 September 1983 that contained 2 eggs. According to several literature reviews, eastern towhees may renest after failed nesting attempts and can raise 2, and in the south sometimes 3, broods per season.

In a literature review, Greenlaw reports mean breeding territory size of 4 acres (1.6 ha) (range 1.6–6 acres (0.64–2.44 ha), n=24) in a mesic oak (Quercus spp.) forest where eastern towhees occurred at a density of 21 males/40 ha. In a xeric pine (Pinus spp.)-oak woodland where eastern towhee density was 32 males/40 ha, mean eastern towhee territory size was 3 acres (1.2 ha) (range 1.8–4 acres (0.71–1.65 ha), n=20). In Massachusetts, mean male eastern towhee territory size was about 1.3 acres (0.52 ha), and female eastern towhee territory size was 1.1 acres (0.45 ha). Territory size changed over the course of the breeding season and was not significantly (p>0.05) affected by reductions in food availability of 30% or less. During the winter eastern towhees are not as territorial and may be seen in mixed species flocks. Daily movement of eastern towhees in loblolly (P. taeda) and longleaf pine (P. palustris) forests and clearcuts in South Carolina averaged 325 feet (99 m) per day. Only 2 females, out of 11 females and 9 males, stayed within the stand where they were captured for the duration of a 10-week study.

Eastern towhees have fairly strong fidelity to breeding territories. In an oak forest in New Jersey, adult eastern towhee return rates were 20% the 1st year after banding and 43% in subsequent years. Between 1960 and 1967, the maximum number of eastern towhee returns to the site was 5. In a Pennsylvania woodlot observed between 1962 and 1967, an eastern towhee returned to the site for 4 consecutive years.

Several reviews report eastern towhee clutch sizes from 2 to 6 eggs, with means ranging from 2.45 to 3.6 eggs per nest. All 5 eastern towhee nests on Sanibel Island, Florida, contained 3 eggs. Eastern towhees in 2 pitch pine (P. rigida) barrens sites in New Jersey and New York had a later median egg laying date (mid-June) and significantly (p<0.05) smaller average early nest clutch sizes (NJ=2.67, NY=3.25) than those in an oak-hickory (Carya spp.) site, which had a median egg-laying date in early June and an average early nest clutch size of 3.88. Food availability likely explains at least some of the differences between the 2 habitat types. Eggs are incubated by the female for 12 or 13 days. After hatching both parents feed the young, which fledge 10 to 12 days later and are dependent on parental care for about another month.

A wide range of eastern towhee nest success values have been reported. On Sanibel Island, 1 of the 5 eastern towhee nests observed was successful. In Louisiana, average daily nest success rate was 95.3% on a bottomland hardwood forest site. The same study found a 92.6% average daily nest success rate in a 6-year-old managed cottonwood (Populus spp.) plantation in Alabama. Average eastern towhee nest success across mixed bigtooth (P. grandidentata) and quaking aspen (P. tremuloides) stands of varying ages in Pennsylvania was 48.1%. In South Carolina, only 1 of 10 nests was successful, and the mean daily nest survival rate was 62.9%. This low value was explained by high levels of predation. Due to lower nest success rates of Bachman's sparrow (Aimophila aestivalis) than the previous year, it is suggested that eastern towhee nest success may have been measured during a comparatively poor year.

Compared to nests, adult towhee survival rates are high. Average weekly adult survival rate of eastern towhees in a South Carolina study area was 99.3%. This rate was obtained from radio-marked eastern towhees and represented the pooled survival of both sexes and from 2 South Carolina sites, young and mature stands of loblolly and longleaf pine. Between 1962 and 1967 in Pennsylvania, annual survival of breeding eastern towhees calculated from mistnetting recaptures was 58%. According to a literature review, both males and females become reproductively mature in their 2nd year. Eastern towhees of over 12 years old have been reported in the wild.