Birds nest during the spring and summer months to raise their young. The exact timing of nesting varies by species and region, but most birds in temperate climates are done nesting by late summer or early fall.
When Does Nesting Season Start?
Nesting season corresponds with springtime and the availability of abundant food sources. The onset of nesting can vary from late winter through mid-spring depending on the climate. Some of the earliest nesters include:
- Robins – Begin nesting in late February and March in southern states.
- Red-winged Blackbirds – Start nesting in March and April.
- Hummingbirds – Start building nests as early as January in southern climates.
Other birds nest later in spring or in early summer, such as:
- Barn Swallows – Nest from April to June.
- Eastern Bluebirds – Start nesting in April or May.
- American Goldfinches – Nest from late May through July.
The exact timing depends on the normal spring temperatures in that area. Further north, nesting is delayed until late spring and early summer when temperatures are warmer and more food is available.
When Does Nesting Season End?
Most songbirds are done with nesting by late summer or early fall. Some reasons nesting tapers off include:
- Decline in food sources like insects and fruit.
- Shorter days provide less time to gather food.
- Some birds molt old feathers and are unable to fly well while new feathers grow in.
- Young birds from early broods are now independent.
Here are typical end dates for nesting season by region:
Region | Nesting Ends |
---|---|
Southern States | July – August |
Northeastern States | June – July |
Midwestern States | July – August |
Western States | June – July |
The last clutches are typically fledged by August or September in most regions. Some late nesters like American Goldfinches may continue into early fall.
Exceptions and Special Cases
While most birds follow similar timelines, there are exceptions:
- Double brooding species – Some birds nest twice per season such as Eastern Bluebirds, Blue-gray Gnatcatchers, and House Wrens.
- Year-round residents – Tropical birds like parrots nest year-round. Hummingbirds in subtropical climates may nest multiple times per year.
- Late nesters – American Goldfinches nest later, starting in June through September.
- Second attempts – If a nest fails, some birds will build another nest and lay again.
Additionally, backyard bird feeding and artificial nest sites can extend the normal nesting period. With a supplemental food source, some birds may nest earlier or lay more clutches.
Changes in Nesting Seasons
Climate change is altering nesting seasons for many species. Warmer spring weather is causing earlier nest initiation for over 30 species monitored in the US. However, not all aspects of the breeding season are shifting at the same rate.
Some observations include:
- Arrival at breeding grounds advancing by over 1 week from 1959-1993 in some species
- Egg laying and hatching occurring earlier by up to 9 days in tree swallows
- Mismatch between peak food availability and nesting in some areas
- Higher temperatures linked to lower reproductive success
These effects make breeding birds more vulnerable. However, the exact impacts on populations are still being studied. Moving forward, conservation efforts will need to consider the influence of climate change on nesting cycles.
How to Tell When Birds are Done Nesting
Here are signs that indicate birds in your area are done with nesting for the season:
- Singing and territorial activity decreases.
- Nestbuilding ceases.
- Adults are seen feeding fledglings on their own.
- Evidence of feathers and droppings around nest sites disappears.
- Nests are empty and disintegrating.
- Young birds form flocks in late summer.
Once all these indicators are observed, you can be confident birds have finished breeding for the year. This signals the start of other behaviors like molting and migrating south.
Conclusion
Most birds in temperate North America complete nesting activities from spring through late summer. Exact timing varies by species and region, with early nesters starting as early as February in southern areas. Late summer nesters like American Goldfinches may continue into September. Tropical species and backyard birds can extend the nesting season longer with supplemental feeding. But for most songbirds, breeding ends by late summer or early fall once food declines and days shorten. This marks the transition from raising young to other behaviors like molting in preparation for migration.