Introduction
The Little Owl is a species of open country, favouring lowland habitats such as farmland, parkland and orchards. Introduced from the Continent during the latter part of the 19th century, the species can be found breeding across England and Wales, just reaching Scotland in the north. Populations are in decline, both here in the UK and elsewhere in Europe, making studies of breeding ecology and survival all the more important.
Calls and identification
Calls
Little Owls make a variety of different calls, the most commonly heard of which is a rather shrill yelping alarm call. The male’s song uses a repeated series of rather nasal sounding ‘gwooooohk’ calls, each of which has a slight upward inflection. Both sexes may use a soft contact call.
Little Owl chicks make a hissing call when begging for food; this is shorter and higher pitched than that of young Barn Owls.
Identification
The Little Owl is our smallest owl, not much bigger than a Song Thrush but chunky in appearance. The upperparts are grey-brown and the plumage is often spotted with white.
The pale underparts are densely streaked with darker brown markings. The piercing stare is emphasised by the dark eyes, yellow irises and the strongly marked pale eyebrows. Both sexes are similar in their appearance.
Ecology and conservation
Ecology
The Little Owl is not a native species, having been introduced to Britain in the 1870s, but it appears to have occupied a vacant niche without having any detrimental impact on other species. Numbers and breeding distribution increased gradually, reaching an estimated breeding population of between 4,000 and 8,500 pairs at the time of Project Barn Owl. The current distribution extends across England, north to the Scottish borders and west into Wales, where it is largely confined to Anglesey and to eastern parts of the country. There have been very few records from Ireland.
Pairs remain on their breeding territories throughout the year, with territorial calling evident during autumn – when young birds are searching for breeding territories – and again during spring. Small cavities are favoured for breeding, these often located within hedgerow trees or the walls of old agricultural buildings. Favoured nesting chambers tend to be located some distance from the cavity entrance and with little daylight reaching them. The male will often perch close to the nest cavity while his mate is incubating her clutch of eggs.
Little Owls often hunt from a perch, taking small mammals and large invertebrates, including earthworms, cockchafers and other beetles. There is evidence to suggest that breeding success is linked to the availability of small mammals, though some pairs evidently do well on other prey; a pair breeding on the island of Skomer, for example, took a large number of Storm Petrels.
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Key facts |
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Clutch Size: |
3 – 4 eggs |
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Incubation: |
27 - 29 days |
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Fledging: |
30 – 35 days |
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First Clutches Laid: |
April - May |
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Number of Broods: |
1 |
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Age at First Breeding: |
1 year |
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Typical Lifespan: |
3 years |
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Maximum Age from Ringing: |
13 years 10 months 3 days (set in 2016) |
Conservation
Although the Breeding Bird Survey trend for Little Owl shows significant variation, it is clear that there has been a marked downturn in the fortunes of this owl over recent decades. A figure of c. 4,000 to 8,500 breeding pairs from the BTO/Hawk & Owl Trust's Project Barn Owl was the first replicable population estimate for this species in the UK, since when numbers have almost certainly declined. There is very little evidence available from the UK regarding the causes of the population decline. However, evidence from mainland Europe suggests that population changes are driven mainly by changes in survival, operating both within the breeding season and at other times of the year.
Changes within the farming landscapes occupied by the species may be driving the observed population trend, with decreases in the availability of favoured hunting habitat and shrinking populations of certain prey. There is also some concern over environmental contaminants, including heavy metal pollution and pesticides.
Knowledge gaps and our work
Knowledge gaps
Given the continued decline suggested by annual monitoring studies there is a case for securing a new national population estimate. However, short-term efforts may be better directed towards collecting more detailed information on survival (both adult and juvenile) and breeding success.
Efforts to determine whether the drivers of population change evident elsewhere in Europe are applicable in the UK would also be worthwhile, as would a better understanding of the link between food availability and breeding success.
BTO work
BTO produced the first repeatable and robust population estimate for UK Little Owls as part of Project Barn Owl, and continues to collect annual monitoring information through the Breeding Bird Survey, Ringing Scheme and Nest Record Scheme. A targeted study on Little Owl survival is being carried out through the Retrapping Adults for Survival project and the wish is to bring in other local studies to broaden the geographical spread for this work. Roughly 150 Little Owl nest sites are monitored each year through the BTO Nest Record Scheme, with 350 or so chicks and 60 adults ringed annually, the latter providing key information on survival rates and how these change over time.
Methods for surveying and monitoring Little Owls are being developed by BTO, with a view to delivering a framework for core monitoring of this species across Britain. The use of tape playback for the census of Little Owl populations has been tested by BTO researchers and published in the journal Bird Study. By working with local groups and individuals we hope to increase the amount of information being collected and to plug the gaps in our knowledge that need to be filled.
Useful resources
Little Owl Nest Box Design
This downloadable cutting plan is for a design that incorporates an internal tunnel to reduce the amount of light reaching the nesting chamber.
Little Owl Monitoring Guide
Best practice guidelines for ringers and nest recorders participating in the BTO Ringing Scheme or Nest Recording Scheme.
