The Eastern screech owl (Megascops asio) is a small owl found in woods across much of eastern North America. Screech owls are known for their eerie, shivering calls, which have led to their common name. These compact owls have prominent ear tufts, yellow eyes, and mottled gray and brown plumage that provides excellent camouflage against tree bark.
Eastern screech owls are widespread across eastern North America but their populations are declining in some areas. Loss of woodland habitat is reducing available nesting and roosting sites for these cavity-nesting birds. However, Eastern screech owls are still fairly common over much of their range. Determining exactly how rare or common the Eastern screech owl is requires looking at their population numbers and conservation status.
Eastern Screech Owl Population
Estimating the total population of Eastern screech owls is challenging. They are nocturnal and well-camouflaged, making them difficult to detect and count. Most population estimates are based on extrapolations from limited survey data.
According to the Cornell Lab of Ornithology, the global breeding population of Eastern screech owls is estimated at over 4 million birds. The vast majority of these live in the United States and Canada. However, coming up with a precise population number is impossible for this elusive species. Trends in local populations can give a better sense of how rare or common they are in different areas.
Population Trends
Eastern screech owl populations appear to be declining in the northern parts of their range but are more stable in the southern United States. The reasons for these declines are not fully understood but habitat loss is likely a major factor.
According to the Breeding Bird Survey, Eastern screech owls declined significantly in the U.S. states of Minnesota, Wisconsin, and Michigan from 1966 to 2015. The population trajectory appears to be more stable in southern states during the same period.
In Canada, Eastern screech owl populations significantly declined by over 50% between 1970 and 2014 according to the North American Breeding Bird Survey. However, trends vary regionally with more stable populations in eastern Canada and decreases out west.
Overall, steeper declines in northern range states indicate that Eastern screech owls are becoming rarer at the edges of their range. But they remain fairly common within the core central and southern parts of their range.
Density and Abundance
Looking at the density, or number of Eastern screech owls per unit area, also gives a sense of how common they are. Research in Missouri found densities ranging from 1 pair per 8 to 25 hectares (approximately 20-60 acres) of woodland habitat. This equates to approximately 4-13 pairs per square mile.
Parts of Wisconsin, Illinois, and Arkansas have documented even higher densities of up to 20 pairs per square mile. Eastern screech owls are considered common year-round residents throughout Florida, Georgia, South Carolina and other southeastern states where suitable habitat is abundant.
So while Eastern screech owl populations have declined in certain northern areas, their abundance and density throughout much of the eastern U.S. indicates they are still a fairly common species over most of their range. But local habitat loss continues to threaten their numbers.
Conservation Status
To determine how rare or common a species is, conservation organizations assess factors such as population trends, total population size, breeding range, and severity of threats. These assessments place species into categories reflecting their extinction risk. Several organizations have evaluated the conservation status of the Eastern screech owl.
IUCN Red List
The International Union for Conservation of Nature (IUCN) Red List categorizes species extinction risk worldwide. The Eastern screech owl is listed as a Species of Least Concern on the IUCN Red List. Their large range and population size means they are not considered globally threatened. However, the IUCN notes that some local populations are in decline.
Federal Status
Under the U.S. Endangered Species Act, the Eastern screech owl is not listed or considered a candidate for federal endangered or threatened status. Again, this indicates it is not rare or at high risk across its widespread range. However, it receives legal protections under the Migratory Bird Treaty Act which makes harming or killing screech owls or disturbing their nests illegal.
State-Level Statuses
State wildlife agencies within the Eastern screech owl’s range have also assessed its conservation status:
State | Listing Status |
---|---|
Alabama | Common resident |
Arkansas | Secure |
Connecticut | Threatened |
Delaware | Endangered |
Florida | Not listed |
Georgia | Not listed |
Illinois | Threatened |
Indiana | Not listed |
Iowa | Endangered |
Kentucky | Not listed |
Maine | Endangered |
Maryland | In need of conservation |
Massachusetts | Special concern |
Michigan | Threatened |
Minnesota | Endangered |
Mississippi | Not listed |
Missouri | Not listed |
New Hampshire | Threatened |
New Jersey | Threatened |
New York | Special concern |
North Carolina | Not listed |
Ohio | Not listed |
Oklahoma | Secure |
Pennsylvania | Not listed |
Rhode Island | Threatened |
South Carolina | Not listed |
Tennessee | Not listed |
Vermont | Threatened |
Virginia | Not listed |
West Virginia | Stable |
Wisconsin | Threatened |
In the northern parts of its range, including New England and the upper Midwest, the Eastern screech owl is listed as endangered, threatened, or of special concern by state wildlife agencies. Further south it is not listed or listed as stable/secure. This matches broader trends of declines in the north and more stable populations in the south.
Summary
In summary, while Eastern screech owl populations have declined in parts of their northern range, the species remains fairly common over most of its eastern North American distribution:
– Global population estimated to be over 4 million but difficult to survey.
– Considered common year-round residents of southeastern states.
– Density estimates show 4-20 breeding pairs per square mile in ideal habitat.
– Not globally threatened and unlisted across much of range according to conservation organizations.
– Listed as threatened/endangered in several northern states with declining populations.
– Protected under federal law but not considered nationally endangered.
– IUCN Red List categorizes them as a Species of Least Concern.
The Eastern screech owl’s large total population and expansive range means it is not a globally rare or endangered species. However, habitat loss and declining populations in parts of their northern range warrant ongoing monitoring and conservation action to maintain this iconic woods owl. Protecting mature forests and woodland patches, and setting aside natural cavities and nest boxes, will benefit Eastern screech owls. Their haunting nighttime calls should continue to echo through eastern forests if conservation efforts can preserve their declining northern populations.