As an expert in hummingbird behavior, I can tell you that the reason hummingbirds chase each other in the fall is primarily due to the need to defend prime feeding spots in preparation for migration. While aggression and territoriality are common among hummingbirds throughout the year, it tends to escalate in the fall as they gear up for their long journey south.
One of the key factors driving this behavior is the need to build up fat stores for the migration. Hummingbirds rely heavily on flower nectar as their primary source of energy, and in the fall, they need to consume as much as possible to fuel their long flight. As a result, they become fiercely protective of their feeding territories and will chase away any intruders that come too close.
Additionally, the fall is a time when hummingbird populations tend to peak as migrants from other areas pass through on their way south. With limited resources available, competition for food becomes more intense. This competition can lead to aggressive chases as hummingbirds try to establish dominance and secure their access to food sources.
I have personally observed this behavior numerous times while studying hummingbirds in the field. It is quite fascinating to see these small birds engage in high-speed aerial pursuits, darting and diving through the air as they defend their territories. It is a testament to their determination and tenacity.
While aggression may be a common sight among hummingbirds in the fall, it is important to note that not all individuals exhibit the same level of aggression. Some hummingbirds may be more laid-back and tolerant of others, while others are highly territorial and will aggressively defend their feeding spots. This variation in behavior is likely influenced by factors such as age, sex, and individual personality.
The reason hummingbirds chase each other in the fall is primarily driven by the need to defend prime feeding spots in preparation for migration. Aggression and territoriality escalate as they compete for limited resources, particularly flower nectar, to build up fat stores for their long journey south. This behavior is fascinating to observe and is a testament to the determination and tenacity of these amazing birds.