Snowy plovers are small shorebirds that live in coastal areas around the world. They have light colored plumage that helps camouflage them against sandy beaches. Snowy plovers eat a variety of small invertebrates that they find along the shoreline and in tidal areas, including flies. Flies make up a significant part of the snowy plover’s diet, especially during summer months when fly populations increase. Snowy plovers have evolved some interesting behaviors and adaptations to help them successfully catch and eat flies.
Running and Pecking
One of the main ways snowy plovers catch flies is by running around pecking at them. Snowy plovers have large eyes positioned on the sides of their head, giving them nearly 360 degree vision to spot flies while probing the sand. When they see a fly, snowy plovers will quickly run after it on their long legs and then peck to grab the fly in their bill. Snowy plovers peck extremely fast, making it hard for flies to escape. This running and pecking method allows snowy plovers to cover a large foraging area and catch many flies.
Fly-catching Technique
Snowy plovers also use a fly-catching technique called “foot trembling.” While standing still, snowy plovers will begin rapidly vibrating one foot up and down in the substrate. This vibration mimics the movement of larval insects and attracts flies down to investigate. When the fly gets close, the plover strikes with its bill and consumes the fly. This foot trembling adaptation allows snowy plovers to conserve energy instead of running around, while still being able to catch flies.
Head Tilting and Orienting
Another interesting behavior snowy plovers use when fly hunting is head tilting and orienting. Snowy plovers will tilt their head side to side to help detect flies above them. They can also reorient their body position to face into the wind. This allows them to see flies more easily as the wind blows them closer, and helps the plovers time their pecks accurately. Head movements help snowy plovers zero in on flies and line up effective pecking attacks.
Foraging in Optimal Habitats
Snowy plovers primarily hunt for flies in habitats where flies tend to congregate. Mudflats, tidal pools, wet sand, and shoreline debris like seaweed and driftwood accumulate flies due to moisture, food sources, and protection from wind. Snowy plovers will actively seek out these fly hotspots and focus their foraging in these areas where flies are abundant and can be caught more readily.
Taking Advantage of Environmental Conditions
Certain environmental conditions can increase fly activity and snowy plovers take advantage of these scenarios. On calm, warm days, flies are more active and snowy plovers will seize these opportunities to hunt. During early morning and late afternoon when temperatures are cooler, flies are more sluggish and easier for plovers to catch. After summer rains, snowy plovers will immediately target any tidal pools or puddles where flies aggregate.
Foraging in Flocks
Snowy plovers often forage for flies in loose flocks. This may help flush more flies up for the group to catch. It also allows the plovers to cover more ground and reduce competition over resources. The birds will run rapidly together through prime fly zones while pecking. This coordinated group strategy likely improves their collective success catching flies.
Predator Avoidance
While focused on catching flies, snowy plovers must also remain vigilant against potential predators. Their open coastal habitats leave them vulnerable to birds of prey and other predators. Snowy plovers rely on camouflage and their large scanning eyes to detect threats overhead or on the horizon. If danger approaches, the plovers give alarm calls and then flee rapidly on foot away from the predator. This interrupts their fly catching, so plovers tend to forage in sprints, maximizing feeding before needing to retreat for safety.
Aggressive Defense of Resources
Snowy plovers will aggressively defend prime fly catching spots from other snowy plovers. They frequently exhibit territorial disputes and attempt to chase competitors away by lunging at them, pecking, and vocalizing threats. This ensures each bird has adequate access to flies without overload competition. However, snowy plovers must also balance resource defense with the need to remain vigilant for predators.
Effect of Disturbance
Human disturbance can negatively impact snowy plovers’ ability to effectively catch flies. Recreational activities on beaches frequented by snowy plovers often interrupt their foraging patterns. The birds must expend more energy avoiding people and pets, leaving them less successful at fly catching. Human disturbances that alter fly habitats like tidal pools can also reduce food availability. Minimizing disturbance is key to supporting snowy plover fly foraging.
Adaptations for Eating Flies
Snowy plovers have some helpful adaptations suited for consuming flies once caught:
- Serrated bill edges – help grip and cut up flies
- Rapid swallowing – down flies quickly before they escape
- Digestive enzymes – break down fly exoskeletons
- Energy efficient – flies provide substantial nutrition for small plovers
These features allow snowy plovers to take full advantage of the flies they work hard to catch.
Differences Based on Age and Season
Snowy plover feeding strategies differ slightly based on the bird’s age and the season:
Age
- Chicks – get fed flies by parents for first few weeks, then begin self-feeding
- Juveniles – less efficient at fly catching initially but improve with experience
- Adults – most adept at fly catching techniques
Season
- Summer – focus is on flies due to peak populations
- Spring/Fall – flies supplemented with other insects and crustaceans
- Winter – fewer flies available, rely more on marine invertebrates
This flexibility allows snowy plovers to thrive across seasons and life stages.
Conclusion
In conclusion, snowy plovers are remarkably adapted for catching and eating flies, an important part of their coastal diet. They use strategies like foot trembling, head movements, foraging in flocks, and targeting prime habitats to maximize their fly hunting success. Fly catching comes instinctually but improves with age and experience. Snowy plovers’ ongoing reliance on flies as a food source highlights the importance of protecting their fragile coastal ecosystems. Maintaining healthy tidal zones and undisturbed beaches will be key to ensuring snowy plovers can continue exhibiting their amazing fly-catching behaviors and flourish into the future.