Blog #434 Verbal Communication (repost of Blog #246)

Fledgling Osprey: mid-level intensity solicitation or begging for food, courtesy of Andy Morffew.

Ospreys are noisy birds as they are constantly interacting during the breeding period. Calls are given by both male and female, although some are for females only. Most Osprey vocalizations are accompanied by visual body postures or displays. Listen carefully and you will grasp the general ideas, if not the specific messages. Osprey vocalizations are simple—there are nest chirps, solicitations (food-begging), alarm and guarding calls, excited calls, and defensive screaming. However, there are many subtleties involving tone and intensity. Their calls are individualistic, allowing Ospreys to recognize each other by voice. Cornell Lab of OrnithologMacaulay Library (https://www.macaulaylibrary.org) has recordings of over 60 Ospreys from North and South America, allowing the listener to compare variations in their deliveries. Superficially, Osprey language seems rather limited, but Ursula and Orpheus have no problem expressing themselves and communicating.

Osprey family members make many vocalizations as they interact in the nest. When the breeding pair greet each other, their chirps are soft, almost sweet. The low, soft, reassuring chirps between parents and chicks are universal in the animal kingdom. Orpheus’s loud cries as he delivers a fish to his noisy family suggests dinner is ready! Chicks under two weeks of age give weak “guard calls” when fed. The nestlings learn to beg for food as their mother does. As they learn to flap their wings, they can sometimes give “screaming calls” in their excitement. Ursula’s sudden and harsh “alarm calls” announce danger and order her brood to lie pancaked in the nest for safety. Once the young fledge, their chirps are important in keeping the family in touch during the day.

Nestlings giving low level alarm calls, courtesy of Cindy Sedlacek.

In 1993 Bretagnolle and Thibault (Auk 110:736-751) catalogued the meaning and function of Osprey communication and found 11 visual displays and 5 acoustic signals, which they deduced from both the context in which they occurred and their effects on the receiver. The 11 visual displays are described in Blog #434 entitled, Visual Communication. The 5 acoustic signals or calls are described below.

ALARM CALLS consist of short, clear whistles that fall in pitch—Cheereek! Cheereek! Cheereek! Alarm calls are staccato, insistent, short whistles that fall in pitch and then morph into more excited high-pitched screams as the threat—be it human, fox, eagle or raven—approaches. This startling call is the only Osprey vocalizations convey signals without the addition of a visual displays; the alarm display is most often performed prior to the call. This call is usually given when the perpetrator is within 50-100 yards from the nest, depending on the type of disturbance and the individual’s habituation. Both male and females give alarm calls, but the male’s is higher pitched than the larger bodied female. Alarm calls often changes to “excited calls”—harsh, guttural croaks—when birds are stressed by humans close to their nests.

SOLICITATION OR BEGGING CALLS: The solicitation or food begging calls consist of a series of rapid short call notes given only by the female mostly in the presence of a male. These repetitive cries, heard throughout the breeding season, sound like a series of high-pitched squeaky Cheeerp! Cheeerp! Cheeerp! strung together. Solicitation calls are one of the types of calls most frequently heard during the breeding season. Ursula and her chicks solicit or beg for food from Orpheus when they are hungry and want fish. The calls become intense if they see him nearby with a fish.

Begging calls may begin with quiet rounds that become louder and more frequent if the male does not respond. These solicitations can be of three intensities from low to high: the more intense the need, the longer and shriller the cries become. The highest intensity occurs when the male has a fish. The female often assumes a submissive posture as she cries, holding her body horizontally, with her crest-feathers slightly erected and her wings held close to her body. Regardless of the intensity, these solicitation cries mean one thing, and one thing only: FEED ME!

Nestling begging for good, courtesy of Cindy Sedlacek.

Females will also make solicitation calls when the male is perched in a nearby tree. Calls in these circumstances may not be intended to beg for food and their purpose and meaning are unclear.

Osprey are as different from each other as are humans. Some females can be noisier than others. Males respond to their mate’s begging cries differently. Responsive males like Orpheus react immediately and surrender their fish. Less motivated idlers and males stressed to their energetic limits are less responsive, ignoring begging cries for hours. High intensity begging calls are loud and unrelenting, and the longer a female is ignored, the more adamant she becomes. Considering their excellent hearing, it is difficult to understand how a male can disregard these urgent messages. The selective hearing of the males and amplified calls from the female is shared by humans.

If a female is not fed enough by her mate, she may solicit food and even copulate with intruder Ospreys, which is not in the best interest of her mate. Although Ospreys usually mate for life, the rare separation ensues if a female is not fed adequately during incubation or if the clutch starves. The longer Osprey pairs are together, the better they communicate and respond appropriately. It takes some males years to learn to share their catches with their mates. Better communication means fosters cooperation, which leads to efficient nesting, successful breeding, and raising of the young.

Male giving female a fish, courtesy of Andy Morffew.

GUARDING CALL and DEFENSE SCREAMS. Guard calls consist of a series of high pitch calls interspersed with screeches. Guard Calls are a series of slow, whistled chirps, descending in pitch, sometimes followed by two or three more intensive wavering notes if the threat persists. Some liken the sound to a teapot letting off steam. Osprey expert Alan Poole describes the call as whistled, down-slurred notes—tioop-tioop …tiiiioop— slow and wavering at the end. These are the first lines of defense against an intruder approaching the nest. If the intruder continues to approach, escalating the threat, the call becomes an intense, higher-pitched, quicker defensive scream. These calls are given by both sexes and are heeded immediately. If Ursula gives this call, her brood will immediately camouflage themselves lying in the nest and Orpheus will come to the nest to help repel the danger.

If the intruder continues closer, guard calls from Ursula and her grown chicks escalate into screaming defensive calls. These furious squeals—Cheereek! Cheereek! Cheereek!—intensify with the approach of the threat. The screaming nest owner will assume a threatening posture discussed in blog #438. The frantic calls become higher pitched during fights. If the intruder continues its threat, Orpheus will instigate a high-speed chase to drive the bird away. The call becomes explosive if the threat escalates —such as the approach of an eagle, raven, or great-horned owl.

Fledge giving a defensive scream.

The meaning of Osprey guard calls can be confusing at times as both birds also give it apparently just to communicate when no intruder is within sight.




MATING CALL OR SCREAMING CALL: To claim Ursula’s full attention while he courts her with a sky dance, Orpheus lets out modified long screeching whistles or “defensive screaming call—"Cheereek! Cheereek! Cheereek! —similar to the alarm call. However, to attract Ursula instead of scaring her away, Orpheus morphs the call by taking away its defensive edge and performs his enticing courtship maneuvers. The meaning of Osprey guard calls can be confusing at times as both birds also give it apparently just to communicate when no intruder is within sight.

Orpheus and the other males also give screaming calls—Cheereek! Cheereek! Cheereek! —as part of their aerial courtship displays, which reminds us of the many functions of this vocalization: attracting mates, claiming territory, and alerting neighbors and mates to danger.

Adult male screaming and chasing an intruder, courtesy of Karel and Cindy Sedlacek.

EXCITED CALL: The alarm call can change to an “excited call” when the birds are highly stressed. The excited call is a harsh, rasping, guttural “ick-ick-ick! and often punctuates long strings of screaming or solicitation calls, sounding like a teapot letting off steam. When Ursula is extremely hungry, especially on hot afternoons, she often adds several rounds of “ick-ick-ick!” to the end of her begging cries. Perhaps it is her way of muttering under her breath something about Orpheus being a slacker. An example of this can be found at https://bit.ly/2YZEDCm (choose second sound clip by Chris Wood, set counter to 0.25).

Upon detecting a predatory bald eagle near the nest, the male and female Osprey start giving guard calls that turn into excited calls if the eagles get too close to the nest. Under circumstances of close imminent threat guard, calls can sound like screams.

Understanding Osprey-speak can be challenging in the beginning because some of their calls have multiple meanings. As is common throughout the animal world, defensive displays seem similar to breeding behaviors. The calls may sound the same but the behavior and body position of the caller make the different intentions clear.

Eyes to the sky!
Candace

Candace E. Cornell
Friends of Salt Point, Lansing, NY
Cayuga Lake Osprey Network
cec222@gmail.com

Featured Photographers: British photographer Andy Morffew splits his time between Hampshire, England and the Gulf coast of Florida when not travelling to far off place to photograph birds and the rest of the animal kingdom. From spending so much time in the natural environment, Andy is outspoken on how we are damaging the ecosphere.

Cynthia Sedlacek, musician and Director of Data Administration and Reporting at Cornell University, is a surprising artistic talent. Cynthia’s affection and admiration for raptors are evident in her exciting photographs primarily of Ospreys nesting around Cayuga Lake and the red-tailed hawks of the Cornell Campus. Her photographs of local Ospreys are incomparable as she captures their essence, their jizz, and their inner bird. From the hard-to-see nestlings to the fast-flying adults, Cindy goes beyond the pale to catch all aspects of Osprey life in the Cayuga Basin. “My camera allows me to capture their beauty in many ways that the human eye can’t see,” she says, “like their spectacular wing positions and detailed feather patterns.” Cindy and her husband Karel are also avid nest monitors for the Cayuga Lake Osprey Network and video stream footage of the campus hawks.

EYES TO THE SKY!

WATCH!

Salt Point Osprey Nest Cast

READ!

On Osprey Time: Ospreys of the Finger Lakes

VISIT!

Cayuga Lake Osprey Trail Nests Driving Tour

Complete Cayuga Lake Osprey Trail


HELP PROTECT OSPREYS:

•Stay 300 feet away from nests during the breeding season. If the Osprey vocalizes, you are too close! Back off Immediately.

•Carry binoculars to view wildlife from afar.

•Help keep local waters clean, healthy, and safe.

•Recycle used fishing lines, twine, and nets, which can kill Osprey.

•Join the Cayuga Osprey Network and volunteer to help monitor Osprey nests: cec222@gmail.com.