Birds build nests for a variety of reasons, including for laying and incubating eggs, sheltering young, and even just for resting. Given how much time and effort goes into building a nest, it’s understandable that we might assume birds rarely abandon or move their nest sites.
However, it turns out that nest moving is actually quite common in the avian world. There are a number of reasons why birds may opt to relocate or build a completely new nest during breeding season.
Why Birds Move Their Nests
Here are some of the top reasons birds may move their nest location:
- Predation – If a nest is threatened by predators, birds may move to a safer location. This is especially common in bird species that nest on the ground or in cavities, which are more vulnerable.
- Disturbances – Major disturbances like habitat destruction, human interference, or storms may cause birds to find a new, more peaceful site.
- Parasitism – Birds whose nests are overrun by parasites will often abandon them and start fresh elsewhere.
- Competition – Crowding and jostling over prime nesting spots may drive some birds to less desirable areas.
- Changing food sources – Birds may relocate closer to new food and water sources.
- Mate availability – Some birds, like eagles, will move nests to be closer to a new mate.
- Better nest sites – Even if a nest site has been satisfactory, birds may move to an even better or more protected spot.
- Nomadic tendencies – Some birds are naturally inclined to wander and nest in multiple locations within a season.
Additionally, certain species have evolved specifically to move nests on a regular basis:
Burrowing Owls
These owls nest underground in abandoned burrows made by prairie dogs, ground squirrels, and other mammals. They frequently change burrows over a breeding season for reasons scientists don’t fully understand. Possible explanations include parasite avoidance, reducing competition, and ensuring territory ownership.
Buff-breasted Sandpipers
Unlike most shorebirds, buff-breasted sandpipers have a unique nesting strategy. Females build up to six different nest scrapes during egg laying, rotating which ones they use. They often shuttle eggs between nests, possibly to distribute resources or confuse predators.
Flamingos
Flamingos nest in large colonies with nest mounds made of mud. They will frequently build new mounds and move between them, for reasons still being researched. Sharing duties, marine tidal changes, and parasite avoidance are possible factors.
How Often Do Birds Move Nests?
Nest moving frequency depends on the bird species. Here are some examples:
- Small songbirds – Usually only move once per season, if at all.
- Waders/shorebirds – May build multiple nests over breeding season and rotate among them.
- Eagles – Often maintain and reuse the same nest for years.
- Parrots – Will reuse cavities or nest boxes across seasons.
- Wild turkeys – Frequently establish new nest sites, sometimes as far as 100 miles away.
- Titmice – Males move nesting material from old nests to start new nests each year.
The table below shows reported rates of nest moving for select bird species:
Species | Rate of Nest Moving |
---|---|
Kentish plover | 67% moved at least once |
Lapwing | 45% moved at least once |
European bee-eater | 56-87% moved |
Upland sandpiper | 30-95% moved |
Grasshopper sparrow | 65% moved |
As seen above, some species such as plovers and bee-eaters are serial nest movers, while others such as eagles and owls are more fixed.
What Type of Nests Do Birds Move?
All types of nests are subject to moving, including:
- Cavity nests – Built in holes in trees, stumps, cliffs, or the ground. Used by owls, woodpeckers, parrots, bluebirds, etc.
- Scrape nests – Shallow depressions scratched out in the dirt. Used by shorebirds, falcons, gulls, terns, etc.
- Cup nests – Circular nests woven from grass and twigs in tree branches or shrubs. Used by most songbirds.
- Platform nests – Larger nests built on a flat surface of branches high up in trees. Used by hawks, eagles, osprey.
- Mound nests – Piles of mud, vegetation, or matted reeds. Used by flamingos, swans, coots, ibises.
- Burrow nests – Underground tunnels used by some seabirds, kingfishers, and burrowing owls.
- Cliff ledges – Bare spaces on cliffs, also called scrapes. Used by gulls, vultures, falcons.
In general, open and exposed nest types like scrapes, mounds, and cliff ledges appear to be moved more often than enclosed nests like cavities or cups.
What Are the Dangers of Moving Nests?
Frequent nest moving does come with some risks and downsides:
- Increased predation – New nests may get discovered by predators before birds can defend them.
- Greater energy expenditure – Finding materials and constructing new nests is energetically costly.
- Higher weather exposure – New sites may lack cover and be more vulnerable to elements.
- Egg loss – Eggs can be damaged or fail to hatch after being moved.
- Brood separation – Young may get left behind if parents move nests.
- Missed breeding season – Late nest moves may prevent pairs from breeding if time runs out.
Birds must weigh these potential downsides against the benefits of having a new nest location.
Do Nest Improvements Count as Moving?
What about cases where birds don’t wholly abandon a nest site, but instead just improve or rebuild their existing nest during incubation and brooding?
Many species engage in “nest sanitation” by removing old nesting material. Others may reinforce the nest structure by adding sticks, moss, or mud as the season progresses. Completely rebuilding a nest in the same exact location is also common.
Researchers don’t consider these in-situ nest improvements to be true nest moving. That label is reserved for instances where a pair establishes an entirely new nest in a different physical site, even if it’s just a few yards away.
So a bird renovating the original nest it built would not count as moving. But a bird building a brand new nest from scratch in a different tree or on new ground would qualify as nest moving.
Do Both Parents Move Nests Together?
When birds decide to switch nesting sites, are both the male and female involved in the move?
In most species, the male does the majority of work when it comes to nest building and selection. So in many cases, it’s the male who chooses the new nesting site while the female follows.
However, regional or seasonal differences in nest moving responsibility have been documented. Some examples:
- Male plovers selected initial nest sites in one population, while females chose replacement nests.
- Female lapwings relocated nests more than males during the early breeding season.
- Later in the season, male lapwings were responsible for most nest moves.
Overall, nest site selection and moving duty seem to be plastic behaviors that can vary within a species as circumstances dictate.
Do Birds Reuse Old Nests or Sticks?
When starting a new nest, do birds recycle any material from the previous one?
Some species do integrate old nesting material into new nests. For example:
- Titmice male birds will carry sticks from an old nest to the new site.
- Bushtits add feathers from a prior nest into their new one.
- Common swifts reuse feathers and sell in successive nests.
- Bank swallows incorporate pieces of old nests into burrows.
Reusing nest parts saves birds time and energy when gathering supplies. It also provides continuity between breeding attempts.
However, many species start completely from scratch when they move nest sites, opting for fresh materials. Birds may avoid old nest parts to decrease parasites or get higher quality components.
Do Cavity Nesters Reuse Cavities?
For birds reliant on cavities like woodpeckers and owls, do they reuse the same cavity across seasons?
Some cavity nesters are loyal to a cavity location, occupying the same tree hole for years if it remains standing. However, choosing a new tree is also fairly common.
According to one study tracking 77 cavity nests over 7 years, bluebirds reused the same cavity in consecutive years 17% of the time. Chickadees did so 31% of the time. Titmice reused 14% of cavities, and woodpeckers did so just 3% of the time.
So while cavities are occasionally reused, most cavity nesting species tend to move among tree sites from year to year.
Conclusion
In summary, nest moving is a flexible strategy used by many types of birds in response to various ecological pressures. While frequent nest relocation has risks, the benefits of finding better locations often outweigh the costs.
Rates of nest moving vary widely based on habitat, life history, nest style, and circumstances. But shifting nest sites within a single season is surprisingly common, even for species once thought to remain fixed.
Understanding the nuances of avian nesting behavior continues to be an active area of research. Tracking nest movements provides insights into the pressures birds face and their capacity to adapt nesting strategies for reproductive success.