Blog #330 Dominance Hierarchy

(L-R) Chick #1 pecks Chick #2 with Chick #3 in the background. 

The three chicks at the Salt Point Natural Area nest have been growing and are forming a natural dominance hierarchy. On several occasions yesterday, the eldest hatchling,  we’ll call it C1 for now, was bullying its younger siblings (middle hatchling C2 and last  

Ophelia feeding fish to her offspring.

chick C3) by pecking and knocking them over. Each time it was just before Orpheus  brought fish to the nest, which abated the conflicts. Bullying and other dominance  behaviors, such as pushing siblings aside to get the first mouthfuls of fish, is a natural  part of establishing this dominance hierarchy. 

Later in the day, Ophelia left the nest for five minutes, a risky move with such young  nestlings. While Ophelia was gone, the siblings got into a free-for-all with the two largest  chicks (C1 and C2) pecking the smallest (C3) and the two largest chicks (C1 and C2) wrestling and pecking each other. Usually the mother’s brooding does not allow room for this behavior. Follow the nestling’s development on Salt Point Osprey Nest Cam  2021. 

Escalating bullying the younger siblings can be a form of brood reduction, a common  strategy in raptors if food supplies suddenly decrease. The first two hungry hatchlings  peck the youngest and smallest sibling to death.  

Brood reduction, necessary for the sake of a healthy generation, adjusts the brood size  to levels at which fishing can be sustained and minimum growth rates in the young can  be maintained. The staggered birth order insures the survival of at least the oldest  nestling to fledging. The average survival rates of hatchlings from multiple risks,  including food availability, predation, parasite load, collisions, and disease rates are  >95% for C1–C3 are >95%, 88%, and 38%, respectively.  

Mombrella with three five-week old chicks, courtesy of Flicker. 

However, brood reduction is not taking place in the Salt Point nest as there is plenty of  food. C1’s rough actions toward its siblings is how chicks establish their dominance over  the others and will sort itself out. Besides, it’s in the 90sº and too hot to rough house. 

Ophelia also spends most of her time playing mombrella, using her body to shade the  young from the sun. Her physical presence maintains a level of law and order. 

Once the size-based hierarchy is established, feedings are based on it. The largest,  oldest sibling, with the highest probability of surviving to fledging, pushes its way to  Ophelia to feed first. When satiated, it moves aside to allow the second hatchling to  

feed. Ophelia and her third hatchling eat what is left. It’s easy to tell when a bird is  satiated because its crop, a food storage pouch below the throat, is bulging.  

The hatchlings, still in their downy coats, are growing before your eyes. Compare the  nest cam footage from one day to the next to see the difference in their size,  coordination, and ability to get around the nest. Ospreys gain 70% of their adult body  weight in the first month of their lives! Keep watching on Salt Point Osprey Nest Cam  2021 to see just how quickly they grow! 

Just after 5 am in the morning in the nest. Notice the chicks’ size differences. 

With his offspring growing rapidly Orpheus now brings 3-6 fish a day to the nest,  ranging from unidentifiable headless specimens to perch, largemouth bass, brown  bullheads, and foot and a half long white suckers. Occasionally, Orpheus will bring

Orpheus with a fresh catch for the family, courtesy of Karel and Cindy Sedlacek. 

colorful goldfish and koi. Trout, a spring favorite, have gone deeper into cooler waters and are rarely on the summer menu.  

Eyes to the sky! 

Candace  

Candace E. Cornell  

Friends of Salt Point  

Cayuga Osprey Network 

Lansing, NY  

cec222@gmail.com

EYES ON OSPREYS  

WATCH! 

Salt Point Osprey Nest Cam 2021 

READ! 

On Osprey Time—A Blog on the Ospreys of Salt Point 

VISIT! 

Cayuga Lake Osprey Trail 

HELP PROTECT OSPREYS  

• AVOID GETTING TOO CLOSE TO NESTING SITES DURING THE BREEDING SEASON. IF AN ANIMAL  VOCALIZES WHEN YOU'RE NEAR, YOU ARE TOO CLOSE! BACK OFF IMMEDIATELY. 

• CARRY BINOCULARS TO VIEW WILDLIFE FROM AFAR. 

• RESTORE, CLEAN, AND PRESERVE LAKESHORE AND WETLAND HABITAT. • RECYCLE USED FISHING LINE, WHICH CAN BE HAZARDOUS TO OSPREY.  

• JOIN THE CAYUGA OSPREY NETWORK AND VOLUNTEER TO HELP MONITOR OSPREY NESTS. WRITE TO: CEC222@GMAIL.COM.

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