Harlequin ducks are a small sea duck species found along rocky coastlines in the northern hemisphere. They are known for their ability to dive to great depths in search of food. But just how deep can these agile divers go?
Quick Facts on Harlequin Duck Diving
Here are some key points about the diving abilities of Harlequin ducks:
- Harlequins can dive to depths of over 60 meters (200 feet).
- Most dives are in the range of 2-20 meters (6-65 feet).
- They have specialized physiology that allows them to endure the pressure at depth.
- Dives typically last around 30 seconds, but can be longer than a minute.
- They dive to find food like mollusks, crustaceans, and other invertebrates.
Harlequin Duck Diving Physiology
Harlequin ducks have several adaptations that allow them to be such proficient divers:
- Dense plumage – Their feathers are specially structured to retain air and provide insulation in cold water.
- Compact body shape – Their compact, stocky shape reduces drag while diving.
- Powerful wings – They use their wings to “fly” underwater.
- Webbed feet – Their partially webbed feet provide propulsion and steering.
- Slow heart rate – They can slow their heart rate to conserve oxygen while underwater.
Additionally, Harlequins have solid bones rather than air-filled bones. This helps them avoid buoyancy issues at depth where the pressure would otherwise compress air-filled spaces.
Dive Depth Records
Most Harlequin duck dives are relatively shallow, but they are capable of diving quite deep on occasion. Some recorded dive depths include:
- 65 m (213 ft) – Long Island, Alaska
- 61 m (200 ft) – Scotland
- 46 m (151 ft) – Japan
- 36 m (118 ft) – California
These record depths are remarkable for a duck that weighs less than 1 kg (2 lbs). By comparison, the deepest diving bird is the emperor penguin at 564 m (1,850 ft).
Dive Durations
In addition to diving deep, Harlequins can stay underwater for an impressively long time. Some observed dive durations include:
- 72 seconds – Long Island, Alaska
- 63 seconds – Coastal British Columbia
- 54 seconds – Scotland
- 46 seconds – California
However, most dives are much shorter, in the 15-30 second range. Dive times tend to increase with depth, since longer is needed to descend, search the bottom, and ascend.
Dive Locations and Habitats
Harlequins demonstrate their remarkable diving abilities across their coastal range. Some of the specific dive sites and habitats include:
- Rocky intertidal zones
- Kelp forests
- Submerged rocky reefs
- Underwater caves and crevices
- Protected bays and coves
- Island coastlines
Food availability tends to determine their dive depth. In warm, shallow waters they can find ample food near the surface. But in colder northern areas, they dive deeper to reach sufficient prey.
Dive Purposes
Harlequins primarily dive for one main purpose – finding food. The foods they target while diving include:
- Mollusks – mussels, clams, snails
- Crustaceans – crabs, shrimp, isopods
- Worms
- Amphipods
- Other invertebrates
Their dives are focused on probing crevices and flipping rocks to uncover these small marine creatures. Males will also dive while courting females.
Diving Ability Comparisons
Harlequin ducks rank among the world’s deepest diving duck species. Here’s how they compare to some other diving ducks:
Duck Species | Maximum Recorded Dive Depth |
---|---|
Long-tailed duck | 60 m (200 ft) |
Common eider | 48 m (157 ft) |
Greater scaup | 18 m (59 ft) |
Harlequin duck | 65 m (213 ft) |
The similarly sized long-tailed duck matches the Harlequin’s diving abilities. But larger eider and scaup ducks don’t dive nearly as deep.
Threats to Deep Diving Abilities
Harlequin ducks have evolved to dive impressively deep. But some modern threats may be impacting their diving abilities:
- Oil spills – Oil ruins the insulation of their feathers.
- Fishing gear entanglement – Lines and nets can limit their movement.
- Prey depletion – Overfishing decreases their food sources.
- Disturbance – Human activity alters their behavior.
Protecting Harlequin habitats and food supplies will be key to preserving their unique diving skills into the future.
Remaining Questions
While Harlequin diving abilities are well documented, some questions remain:
- How do fledglings learn to dive proficiently?
- Do they cooperatively dive in pairs or groups?
- What is their stroke efficiency compared to other diving birds?
- How do populations vary between shallow and deep diving specialists?
Further research with video cameras and telemetry tags could help shed light on these remaining areas of their diving behavior.
Conclusion
Harlequin ducks hold the distinction as one of the deepest diving waterfowl species. Thanks to a suite of specialized adaptations, they are capable of plunging over 60 meters to probe the seafloor in search of food. Understanding how they exploit their coastal habitats can lead to better protection for these acrobatic sea ducks.