How does moulting of primary wing feathers occur in buteos, parabuteos, and accipiters?

In birds of prey such as buteos, parabuteos, and accipiters, moulting of the primary wing feathers typically begins with the innermost primary feather. This process is critical for maintaining the functionality of their wings, as these feathers are essential for flight aerodynamics and control.

Moulting involves the shedding and regrowth of feathers, and starting with the innermost primary allows for more efficient feather replacement, ensuring that the bird maintains enough lift and maneuverability during this period. Additionally, this pattern of moult helps to balance the structural integrity of the wing, as the outer feathers will still provide support and aerodynamics while the innermost ones are being replaced.

The options about starting with the outermost primary or a specific feather number do not reflect the typical moult sequence seen in these species. The irregular fashion of moult doesn't align with the structured pattern observed in their primary feather replacement. Thus, initiating the moult with the innermost primary statistically represents the standard practice in the life cycle of these birds as they grow new feathers to replace the old, ensuring they remain adept at hunting and flying.