Eastern screech owls (Megascops asio) are small owls found throughout eastern North America. They are known for their distinctive calls and ability to camouflage themselves against tree bark. Many people wonder if these owls form lifelong pair bonds with a single mate or frequently find new partners.
Quick Answers
– Evidence suggests eastern screech owls generally mate for life with the same partner year after year.
– However, they may accept a new mate if their previous mate dies or disappears.
– Eastern screech owl pairs work together to defend their nesting territory.
– They roost near each other and duet to reinforce their pair bond.
– Both parents incubate eggs and care for the young owlets once they hatch.
Eastern Screech Owl Breeding Habits
Eastern screech owls breed between March and May depending on their geographic location. Courtship involves the male offering food to the female and duetting together. Once a pair bond forms, the birds remain together on their territory throughout the year.
The male screech owl will select a nesting cavity in a tree hole or manmade nest box and defend the site from other males. The female will lay a clutch of 2-8 eggs which she incubates for about 26 days. The male helps feed her during this time.
Once the eggs hatch, both parents hunt to feed the owlets. The young fledge from the nest after about a month but remain on their parents’ territory for several more weeks. The bonded pair may reuse the same nesting site for many years.
Evidence That They Mate for Life
Several lines of evidence indicate eastern screech owls tend to maintain long-term pair bonds:
- A 13-year banding study found 92% of male screech owls remained with the same mate across breeding seasons if she survived. When the female was lost, the male paired with a new female the next year.
- Pairs reuse and defend the same nesting sites across years.
- Duetting helps pairs identify territorial intruders and strengthen their pair bond.
- Both sexes develop brood patches and share incubation duties.
This monogamous breeding strategy likely evolved because it improves the odds of successful reproduction. Defending a territory and raising demanding hatchlings requires contributions from both the male and female over an extended time period.
How Long Do Pairs Stay Together?
Once eastern screech owls form a pair bond, they typically remain together for multiple breeding seasons or for life. However, a long-term study in New York found:
- Average duration of a pair bond was 2.5 years
- 25% remained together for only 1 year
- 13% remained together for 5+ years
- One pair stayed together for 11 years
Although owls appeared to mate for life in this population, bonds sometimes ended due to the death of one of the birds. Pairs that remained together across multiple years had greater reproductive success.
What Happens If a Mate Dies?
Eastern screech owls whose mate disappears from their territory will accept a new mate. However, they may go through a period of displaying and calling more frequently to try and locate their missing partner first.
A study in Texas found screech owls took new mates after losing their first partner, although they remained in the same territory. Six females paired with 4 different males over 3 years following the males’ disappearances.
This flexibility in pairing allows the owls to reproduce successfully even if their lifelong mate dies. However, the new pair goes through a period of reestablishing their bond and may be less synchronous when breeding at first.
Do Both Parents Raise the Young?
Yes, both the male and female eastern screech owl participate in raising offspring. Some of their key parental roles include:
Male
- Defends the nest territory from intruders
- Guards the female and provides her with food during incubation
- Helps feed newly-hatched chicks
Female
- Lays and incubates the eggs
- Broods young chicks to keep them warm
- Tears apart prey to feed to small owlets
The female typically spends more time at the nest while the male patrols their territory and captures food. But both are invested parents. Having both parents provisioning the demanding hatchlings likely improves chances of fledging success.
How Do Pairs Interact?
Eastern screech owl pairs use various behaviors to reinforce their bond:
Duetting
Screech owls perform duets by matching their calls back and forth. This helps them identify each other, repel intruders, and defend their territory. It also synchronizes breeding and strengthens the pair bond.
Nesting Close Together
Pairs roost side-by-side in cavities or trees near their nest site during the breeding season. The female calls to the male if he strays too far away.
Allopreening
Partners groom each other’s feathers around the head and neck. This behavior reinforces social bonds.
Food Offerings
The male brings prey items to the nesting cavity to entice the female and feed her during incubation. She rewards him by allopreening his feathers.
Do Pairs Always Get Along?
Eastern screech owl pairs do not always harmoniously share parenting duties. One study found:
- 14% of males did not bring enough food to the incubating female.
- Females sometimes had to grab prey from the male to get enough food.
- 5% of males completely failed to provision their mate.
Despite some discord, most pairs successfully reproduced. However, females paired to non-provisioning males were more likely to fail incubation and desert the nest. Cooperation improves breeding success for this mostly monogamous species.
Comparison to Other Owl Species
Not all owl species form lifelong pair bonds like eastern screech owls:
| Species | Mating Strategy |
|---|---|
| Eastern Screech Owls | Mostly monogamous, long-term pair bonds |
| Great Horned Owls | Generally monogamous |
| Snowy Owls | Mostly serially monogamous, new mate each year |
| Northern Saw-whet Owls | Polygamous, males mate with multiple females |
| Boreal Owls | Polyandrous, females mate with multiple males |
| Burrowing Owls | Monogamous in some regions, polygynous in other regions |
The degree of pair bonding and mate fidelity tends to correlate with how much biparental care the young require. More solitary owl species with less demanding offspring are less likely to form permanent pairs.
Conclusion
In summary, the bulk of evidence suggests eastern screech owls generally mate for life. While they may accept a new partner if their mate dies, most remain with one partner across multiple breeding seasons. These monogamous bonds allow them to optimize their reproductive success through joint territory defense, shared incubation duties, and biparental care of the owlets.
