Sandpipers are small shorebirds that are known for their running and chasing behavior. It is common to see large flocks of sandpipers scurrying across beaches and mudflats, chasing after each other. But why do they engage in this seemingly playful and energetic behavior? There are several reasons why sandpipers chase each other.
Territory Defense
One of the main reasons sandpipers chase each other is to defend their feeding territory. Though they forage in large flocks, each bird maintains its own small territory where it feeds. The territories provide enough food resources to sustain individual birds. When other sandpipers encroach on a bird’s territory, the defending sandpiper will chase the intruder out. The chasing and posturing establishes boundaries and reinforces territories within the flock.
Courtship Display
The chasing behavior is also a courtship display in breeding sandpipers. The males will chase females as part of their mating ritual. This shows off the male’s strength, speed, and agility. Females seem to prefer males that are adept chasers, so the courtship chasing has likely evolved as a sexually selected trait. The chases stimulate the female sandpipers and facilitate pairing.
Establishing Dominance
Sandpipers are hierarchical and establish a “pecking order” within flocks. Higher ranking birds chase and peck at lower ranking birds. The aggression helps maintain the social order and access to the best feeding areas. The chasing displays are a constant battle for dominance as sandpipers jostle for position in the flock hierarchy.
Communication and Coordination
The chasing also seems to communicate information and coordinate flock activity. The movements influence foraging behavior and synchronize activities like roosting and migration. Chasing initiates movement and flight in a flock. Additionally, some scientists think the chased birds may be sentinels that signal about predators. So the chasing has an important communication function.
Play Behavior
Some chasing in sandpipers may simply be play. The young birds especially will chase each other exuberantly like children playing tag. This play chasing helps the birds practice flying skills and predator evasion. It also strengthens social bonds between the birds. The fun and play can provide essential development and cohesion benefits to the flock.
Staying Active
The near-constant chasing also helps sandpipers stay active and alert. This energetic activity allows them to ward off predators and react quickly to disturbances. The movement and stimulation seems to create a level of vigilance for potential threats while foraging. So the chasing consists of functional motion rather than idle standing.
Visual Cues
Lastly, the conspicuous chasing behavior provides good visual cues to guide and orient migrating flocks. Landmarks are scarce on open beaches and mudflats, so the dynamic chasing motions give birds visible focal points. The flocks can track the chasers and maintain coordinated movements. So the chasing provides a type of directional “beacon” across wide open spaces.
Conclusion
In summary, sandpipers chase each other for a variety of important reasons. The chasing establishes territory boundaries, displays courtship, creates a pecking order, communicates information, provides play opportunities, keeps the birds active, and offers visual guidance during migration. While the chasing seems haphazard and funny to human observers, it actually has many significant functions related to survival, reproduction, and flock coordination. The chasing behavior evolved over time to support key aspects of sandpiper ecology and behavior.
Sandpiper Chasing Facts and Details
Common Species That Chase
The sandpipers that are most known for chasing behaviors include:
- Western sandpipers
- Semipalmated sandpipers
- Least sandpipers
- Baird’s sandpipers
- Dunlins
- Sanderlings
These species forage in large mixed flocks and migrate long distances in groups, so the chasing helps coordinate flock activities.
How Fast and Far They Chase
Chases are usually short burst flights up to 30 feet. However, longer pursuits of 100 feet or more are not uncommon. The brief bursts reach estimated speeds around 13-15 mph. This is considerably slower than the sandpiper’s maximum flight speed, indicating chasing is not meant to be escapable.
How Much Time They Spend Chasing
During foraging and migration, sandpipers may spend 10-20% of their active time engaged in chasing behaviors. Some estimations indicate sandpipers chase up to 2000 times per day during peak activities!
Key Locations for Observing Chasing
Prime spots to observe chasing behaviors include:
- Coastal mudflats and estuaries during migration – Gray’s Harbor, WA
- Breeding grounds of northern Canada during summer – Yukon Delta, Alaska
- Wintering grounds of Latin America – Marismas Nacionales, Mexico
- Spring and fall stopover sites – Cheyenne Bottoms, KS
Any major migratory stopover site worldwide offers chances to see chasing displays.
Times of Year with Peak Chasing
The most chasing activity occurs during:
- Early fall – August-September
- Spring migration – Late April-Early May
However, chasing can occur year-round as needed.
Season | Chasing Activity Level |
---|---|
Spring Migration | High |
Summer Breeding | Moderate |
Fall Migration | Very High |
Winter | Low |
Unique Aspects of Sandpiper Chasing
Aerobatic Maneuvers
Chased sandpipers will employ sharp, evasive maneuvers to escape pursuit. Twisting, diving, and zig-zagging try to shake their pursuer. Some executes aerial rolls and 180 degree turns rarely seen outside of chases. The escaping sandpipers also gain valuable evasion practice.
Constant Chatter
Sandpipers chase each other while making constant ticking and rattling calls. These vocalizations likely communicate pursuit or surrender. The sounds also help coordinate the flock’s movements and maintain contact.
Exaggerated Running
On the ground, chasing involves exaggerated running with wings flapping. This conspicuous display allows birds to identify chasers and chased from a distance. The vocalizations continue during running as well.
Jumping and Foot Paddling
Sandpipers will jump and foot paddle at each other on the ground. The jumping displays the bird’s strength and startles opponents. Foot paddling rapidly kicks up water or mud to displace a rival from a territory.
Why Foot Paddling Occurs
Foot paddling specifically displays dominance and deters territorial intruders. The splashing mud and water is threatening and unpleasant for more submissive birds. Thus it reinforces territories and hierarchy through physical discomfort.
Scientific Insights into Sandpiper Chasing
Tracking Studies
Scientists have gained insights by attaching radio tags and unique color bands to sandpipers. Tracking individual birds reveals that the chasers are often dominant males or birds defending nest sites. Also, chased birds tend to be subordinates or intruders into other’s territories.
Dominance Hierarchies
Detailed observations of banded birds shows that sandpiper flocks have linear dominance hierarchies. Each bird ranks either dominant or subordinate relative to other individuals. Chasing reinforces these hierarchies for accessing resources.
Energy Expenditure Research
Metabolic research indicates the average sandpiper spends 8% of its daily energy budget on chasing behaviors. While not trivial, this is sustainable thanks to the rich food sources in mudflat habitats. The energy spent establishes territories that enable feeding.
Habitat Carrying Capacity
Ecologists propose chasing intensity relates to habitat carrying capacity and food availability. More chasing suggests increased competition and defensive behavior in crowded or resource-poor areas. Less chasing occurs in high quality habitats.
Impacts of Habitat Loss
Habitat loss may increase chasing frequency and intensity. With fewer feeding areas available, the terrains become more crowded. This leads to heightened competition and chasing to defend territories.
Habitat Quality | Chase Frequency |
---|---|
High | Low |
Moderate | Moderate |
Low | High |
Predator Detection Research
Studies show sandpipers feeding in high density flocks have lower individual vigilance for predators. Chasing may help counter this effect by keeping more birds alert through motion and stimulation.
Unique Predator Defense Adaptations
Sandpipers combine chasing behaviors with specialized adaptations to detect and escape predators in open environments including:
Large Eyes
Sandpipers have very large eyes relative to their body size. This improves visual acuity to spot predators from a distance.
Cryptic Coloration
Their plumage’s mottled browns, grays, and whites blend into the coastal sediments where they feed. This helps camouflage sandpipers from predators.
Vigilant Scanning
Individuals will regularly lift their head up to scan for potential threats while feeding. Their lateral vision facilitates scanning a wide area.
Early Warning Calls
Sentinel birds that spot a predator will emit high-pitched alarm calls. This quickly alerts the flock to take evasive action.
Distraction Displays
When a nest is threatened, the adult sandpiper may perform a distraction display. This involves dragging its wing on the ground to lure the predator away from the nest.
Mass Evading Maneuvers
The highly coordinated flock will take instant evasive action as one unit. Their speed and zig-zagging helps confuse predators.
Conclusion
Sandpipers have many fascinating adaptations to enhance predator detection and avoidance. The combination of cryptic plumage, scanning vigilance, warning calls, distraction displays, and chasing-inspired evasion allows sandpipers to minimize losses. These adaptations help shorebirds survive in expansive coastal environments despite heavy predation pressure.
Fun Facts about Sandpiper Chasing
- People sometimes call sandpipers “wind-up toys” due to their constant chasing and nervous energy.
- The old name “stints” for small sandpipers came from their propensity to stint or skip while chasing.
- In human culture, “sandpiper” is sometimes used metaphorically to mean someone restless, energetic, or flighty.
- Fossil evidence shows proto-sandpipers were chasing each other 34 million years ago.
- Sandpiper chasing intensity inspired biologist Nikolaas Tinbergen’s study of “competitive panic” reactions in animals.
- Sanderling sandpipers chase in circles around flock mates before migratory takeoff. This behavior is called “wheeling.”
- Dunlins perform aerial “moth flights” where they rise quickly then zig-zag down while being chased.
- A group of sandpipers being chased is called a “bevy” while the pursuers are termed a “bind.”
- The record for most sandpipers seen chasing simultaneously is 427 individuals!
Conclusion
While sandpiper chasing may look haphazard and funny to people, it has important evolutionary roots. The chasing behaviors play key roles in territory defense, courtship, communication, predator detection, and flock coordination. Next time you see sandpipers energetically chasing each other, remember they are conducting important business, not just playing! The chasing helps ensure the survival and success of these long-distance migratory shorebirds.