Hummingbirds engage in a dedicated nesting season, a demanding period primarily undertaken by the female. Understanding their nesting patterns reveals their adaptability and the environmental cues guiding reproduction.
Typical Nesting Periods
The nesting season for hummingbirds varies significantly depending on their geographical location and species. In the southern United States, breeding can commence as early as March, while in cooler, northern or mountainous regions, it may not begin until July. Some western species, such as the Anna’s Hummingbird, are notable for starting their nesting activities with the first winter rains, sometimes as early as November or December, and continuing through May or June.
Ruby-throated Hummingbirds, prevalent east of the Mississippi River, typically lay eggs between March and May, with the exact timing influenced by latitude. In areas like Georgia, Ruby-throated Hummingbirds are known to nest twice a year. Rufous Hummingbirds, which breed in the Pacific Northwest, Alaska, and Canada, generally lay their eggs later in the year, usually between April and July. Black-chinned Hummingbirds commonly begin nest construction in April across their widespread range from deserts to mountain forests.
Influences on Nesting Timing
Several environmental factors synchronize hummingbird nesting with optimal conditions for raising young.
Photoperiod, or daylight length, is a primary cue. As days lengthen in spring, physiological changes prompt reproductive behavior.
Temperature also plays a role in nesting decisions. Females prioritize areas where temperatures remain below 96°F to prevent eggs from overheating, as extreme heat can be fatal to embryos. Some species in hotter regions time nesting with cooler months or higher elevations. Wind conditions are also considered, as females select sheltered locations to protect nests from damage and prevent chilling of eggs and chicks.
Food source availability, primarily nectar and insects, is another determinant for nesting success. Hummingbirds require abundant energy for reproduction. Seasonal flower blooms and insect emergence provide sustenance for adults and young. Nesting often aligns with peak floral resources in their habitat.
Multiple Nesting Cycles
Many hummingbird species can raise more than one brood within a single nesting season, particularly in warmer climates where the breeding season is extended. For example, in southern regions or areas where hummingbirds reside year-round, females may successfully raise two to three nests annually. Anna’s Hummingbirds, found along the Pacific Coast, often have two to three broods each year, especially when reliable food sources are present.
In contrast, hummingbirds in northern habitats, where the nesting season is shorter, typically raise only a single brood. The female hummingbird undertakes all nesting duties alone, from building the nest and incubating the eggs to feeding the hatchlings. If a first nesting attempt fails due to factors like predation or harsh weather, the female may build a new nest and re-lay eggs, provided it is early enough in the season.