Author: Matt Perry

Update for Monday, May 27, 2024

Almost every year, we face challenges in distinguishing male from female nestlings in the Utica nest. It’s quite common for us to mistakenly give a female a male name or vice versa. Fortunately, the birds never seem to mind or get offended by our mix-ups. One reliable method for differentiating between the sexes is through measurements, as there is a notable size difference between adult males and females. Female peregrine falcons are generally larger and heavier than males, a trait known as reverse sexual dimorphism. However, this size difference is not as pronounced in nestlings, making it challenging to assess with the naked eye. Detailed measurements of the nestlings’ tarsus (leg bone), beak, and overall weight can provide clues, but these often require careful handling and precise tools, which can be stressful for the birds.

If the Utica birds were subject to banding, then they would be measured and weighed, but since they are not, and it would not be safe to do so at their nest box, we can only make educated guesses regarding their measurements and weights. The complicating factor with gauging the size of our birds is the wide-angle lenses on our nest cameras. They always show a distorted view of the size of the birds and their legs. Generally, whichever bird is closer to the middle of the camera frame looks the largest. It is typically only when the nestlings start emerging from the box and going to the verandas or the cross perch that we get a true idea of their size. This is when we can see them with our roof cameras, which do not distort. This year, it seems particularly hard for us to determine gender via visual inspection. We are still reasonably sure that we have one definite female and one definite male, but the jury is still out, and we may not know for sure until fledging is upon us in a couple of weeks.

Update for Sunday, May 26, 2024

As the days progress, and as the nestling develop, they began to act more like young Peregrines and less like defenseless chicks. Interactions between sibling Peregrine Falcons in the nest are a blend of competition and cooperation, crucial for their development and survival. From hatching, these young birds engage in behaviors reflecting their struggle for resources and family dynamics. Competition for food is a prominent interaction; when a parent brings prey, the nestlings beg vigorously, displaying animated movements and loud calls. Dominant and assertive chicks often secure more food, creating a pecking order within the nest. This hierarchy helps more dominate chicks get the lion’s share of food, although lower ranked chicks rarely suffer from malnutrition since Peregrine parents often provide an overabundance of prey. Beyond food competition, sibling interactions significantly influence the physical and social development of young falcons. As they grow, they engage in play-fighting, including mock attacks, pecking, stealing food from each other, and grappling, which are essential for honing hunting and defensive skills. These activities develop their strength, coordination, and agility, vital for survival once they leave the nest. Additionally, cooperative behaviors such as wing-flapping practice and preening strengthen social bonds and prepare the young falcons for collaborative hunting and survival in the wild. These interactions equip the young birds with the necessary skills and social acumen to thrive as independent predators.

Update for Saturday, May 25, 2024

Ares does very well providing food for his family. Indeed, he spends much of the day and sometimes a good deal of the night hunting. Adult male peregrine falcons have adapted remarkably well to urban environments, achieving high hunting success rates thanks to the abundance of prey and suitable high perches like tall buildings and bridges. These structures mimic the natural cliffs that Peregrines use for nesting and hunting, allowing them to perform their signature stoops, diving at speeds exceeding 200 miles per hour to strike prey with great force. Cities provide a steady food source, with large populations of Pigeons, Starlings, and other birds that thrive on human refuse, making them prime targets for Peregrines. Of course, Ares also can exploit a wide range of prey species that live at the nearby Utica Marsh and other areas along the Mohawk river floodplain.

Studies indicate that urban Peregrine Falcons can achieve hunting success rates as high as 50-70% during certain times of the year. This efficiency is bolstered by the predictable presence of prey and the falcons’ unparalleled speed and agility. Urban prey birds, often less experienced with avian predators, are more vulnerable to attacks. The success of Peregrine Falcons in urban areas underscores their adaptability and resilience, highlighting their ability to coexist and thrive in human-dominated landscapes.

Update for Friday, May 24, 2024

The process of feather growth in nestling Peregrine Falcon is a crucial part of their development, transforming them from helpless hatchlings into fledglings ready for flight. This process begins shortly after hatching and involves several stages, each critical for the young falcons’ survival and eventual independence. When Peregrine chicks hatch, they are covered in a layer of soft, white down feathers. These down feathers provide insulation, keeping the nestlings warm, but they are not suitable for flight. At this stage, the chicks are highly dependent on their parents for warmth, protection, and food. As the juvenile feathers grow, they gradually replace the initial down feathers. The sheath surrounding each new feather breaks down, allowing the feather to unfurl and take its full form. These juvenile feathers are darker and more structured than the down, providing better protection and laying the groundwork for future flight capabilities. By the time the nestlings are about five to six weeks old, they have developed a full set of juvenile feathers, including the critical flight feathers on their wings and tail. The flight feathers, which are stronger and more aerodynamically shaped, are essential for flying. These feathers are meticulously preened by the nestlings to ensure they are in optimal condition.  

The process of feather growth in nestling Peregrine Falcons is a meticulously timed and energy-intensive phase of their early life. From the initial insulating down to the development of robust juvenile feathers, each stage prepares the young falcons for the critical transition from nestbound chicks to adept aerial hunters. This transformation is essential for their survival and marks the beginning of their journey as one of the world’s most formidable avian predators.

Update for Thursday, May 23, 2024

Astrid became very upset today when she perceived workers up on the bank roof. She gave loud cackling calls for at least an hour. She hazed them; she got Ares involved, and she generally put on quite a show. During the breeding season, Peregrine Falcons exhibit highly territorial and aggressive behaviors; they haze intruders or other perceived threats near their nesting sites. These raptors are fiercely protective of their nests, particularly when they occupied by nestlings. Any encroachment by other birds, predators, or humans is met with swift and decisive action to safeguard their offspring.

Peregrine falcons use a combination of aerial maneuvers, vocalizations, and physical attacks to deter intruders. When a threat is detected, they will often launch into the air with rapid, powerful wingbeats, using their considerable speed and agility to confront the intruder. They may dive-bomb the threat in a series of aggressive swoops, coming very close or even making contact with their talons to scare it away. These hazing dives are both intimidating and effective, showcasing the falcon’s prowess as a top predator. In addition to physical hazing, peregrine falcons employ loud, piercing vocalizations to warn off intruders. Their sharp, repetitive cackle calls serve as an auditory deterrent, signaling to the intruder that they have entered a highly defended territory. These vocal displays also alert the mate and any fledglings of potential danger, ensuring that the entire family remains on high alert.