LOOK Closely. How many owls do you see?

February 10, 2019

How many Long-eared Owls did you find? Look closely and you'll find ten!

 

It's been an incredible roost-watching season and this cam is one of our favorites; after all, 32-years ago Denver’s study of Long-eared Owls began with the research question “are communal roosts comprised of family groups, other related individuals, or non-related individuals?” This cam is the perfect compliment to our on-going research and provides unprecedented views of this unique roosting behavior.

 

Long-eared Owls are one of the few owl species in the world who roost communally. Clustering in groups of 2 to 20 individuals, these roosts occur during the non-breeding season - the fall and winter. Communal roosts of up to 100 individuals have been reported, although we have never seen numbers like this in our study areas. Last year’s cam filmed as many as 13 birds in this roost. We have learned that these groups are made-up of different sexes and ages, although rarely comprise members of the same family.

 

So why do Long-eared Owls form these communal roosts? There are several potential reasons. One, grouping together may have thermal advantages during the frigid winter months. Two, it may be a defense against predators – the more eyes on the lookout, the better. And, three, it seems to have social implications for mating: birds from winter roosts turn into the local breeding population. Long-eared Owls are seasonally monogamous but life-long polygamous.

 

The individuals in this roost may be birds who will overwinter in their local breeding area; birds who have migrated from other areas (presumably more northern climates); or birds who are just stopping over for a bit before moving on. Other individuals - those who may have spent the breeding season here - have migrated to other areas. Birds often continue to move around throughout the winter, both within and outside of the study area, depending on food availability and local conditions.

 

Overall we know very little about Long-eared Owl movements, but there are three general strategies:

 

1. Traditional migration: movement to and from breeding area to wintering areas

2. Nomadic migration: moving around to different areas until food and habitat conditions are favorable.

3. Overwinter in breeding grounds.

 

Generally, the research year is divided into three seasons: breeding, migration, and wintering. Right now we are in the wintering season and will be transitioning into the breeding season soon. We are hoping for a strong breeding season which will, ultimately, be determined by food supply in the area. The diet of these nocturnal hunters is mostly comprised of small mammals, such as voles and mice, and occasionally birds. If the small mammal population cannot support the demands of nesting, they will move on to different areas.

 

And as if ten owls roosted together wasn't spectacular enough, did you notice that one of these individuals is much darker than the rest? This individual is expressing some degree of melanism. During our on-going efforts to learn more about Long-eared Owls, we will attempt to capture and band this unique individual to understand more and gather information on age and sex. Melanin mutations - like melanism and albinism - are rare in wild populations and most affected animals are thought to have shortened life expectancy.

 

Melanism is a genetic mutation that causes the excessive production of melanin in animals, often causing them to be entirely black. Melanism, the opposite of albinism, occurs in birds, amphibians, mammals, and reptiles. In some instances, melanism seems to be a product of natural selection, improving an animals’ ability to retain heat or blend in with its surroundings. Melanistic animals can appear so different that they are sometimes mistaken for an entirely different species.

 

Overall, our winter roost cam has been fantastic this season, capturing as many as 11 Long-eared Owls roosting together. All live cams are generously made possible by explore.org.

Check it out here: LONG-EARED LIVE CAM >>

 

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