Action Synopsis: Bird Conservation About Actions

Provide artificial nesting sites for parrots

How is the evidence assessed?
  • Effectiveness
  • Certainty
  • Harms

Study locations

Key messages

  • A before-and-after study from Costa Rica found that the local population of scarlet macaws Ara macao increased following the installation of nest boxes along with several other interventions.
  • Five studies from South and Central America and Mauritius that nest boxes were used by several species of parrots, with one finding an increase in use over time until the majority of the population used them. One replicated study from Peru found that blue-and-yellow macaws Ara ararauna only used modified palms, not ‘boxes’, whilst another replicated study found that scarlet macaws Ara macao used both PVC and wooden boxes, but that PVC lasted much longer.
  • Four studies from Venezuela and Columbia found that several species very rarely, if ever, used nest boxes.
  • Six studies from Central and South America found that parrots nested successfully in nest boxes, with two species showing higher levels of recruitment into the population following nest box erection and another finding that success rates for artificial nests were similar to natural nests.
  • Three studies from South America found that artificial nests had low success rates, in two cases due to poaching.


About key messages

Key messages provide a descriptive index to studies we have found that test this intervention.

Studies are not directly comparable or of equal value. When making decisions based on this evidence, you should consider factors such as study size, study design, reported metrics and relevance of the study to your situation, rather than simply counting the number of studies that support a particular interpretation.

Supporting evidence from individual studies

  1. A replicated trial of two nest box designs in 1992-2000 at a tropical rainforest site in southwest Peru (Brightsmith 2000) found that both designs were used by scarlet macaws Ara macao, with PVC tubes proving more durable than wooden boxes. Eight boxes (45 x 45 x 160 cm with a 15 cm diameter entrance hole) made from tropical cedar Cedrella odorata wood were hung on the tall emergent trees in March 1992, with seven used by macaws (one was occupied by bees). No wooden boxes were useable by September 1999. Five PVC tube nest boxes (30 or 35 cm diameter, two 17 x 15 cm entrance holes, lined with caulk and with wooden or metal top and bottom) were hung in August-September 1992, of which four were occupied in 1993-4. More nest boxes were hung in later years and nine of 12 available boxes were used in the 1999-2000 breeding season.

    Study and other actions tested
  2. A replicated, controlled study (Brightsmith & Figari 2003) in 1999-2003 found that scarlet macaws Ara macao occupied a large number of nest boxes at the same rainforest site as in Brightsmith 2000, with 13 of 14 PVC nest boxes and one of four wooden boxes occupied. Eggs were laid in ten; eggs hatched in six and four (all PVC tubes) fledged at least one chick. Four natural nests were used and three fledged at least one chick. When data were combined with that from 1999-2001, chick survival was similar (75-6%) in natural nests and nest boxes. Hatching rates were lower in PVC nest boxes (of the same type as in Brightsmith 2000, than in natural nests (41% vs. 65%), possibly due to higher temperature fluctuations. Hatching rates in wooden boxes were very high (80%) but the authors note the small sample size may make this result unreliable.

    Study and other actions tested
  3. A replicated study in 1993-9 in a tropical forest on an island in Venezuela (Sanz et al. 2003) found that yellow-shouldered Amazons Amazona barbadensis used repaired natural cavities more often than artificial nest boxes. One box of 14 was used in 1997, a second in 1998, and three in 1999 compared with all 15 repaired natural cavities being repeatedly occupied following repair. Fledging rates were also low for nest boxes; with four out of five clutches being removed by poachers (the remaining clutch fledged three chicks). Nest boxes were wooden, 160 x 30 x 30 cm with a 20 x 15 cm entrance hole, had 10 cm of woodchips inside and grooves to allow parrots to climb out. Boxes were placed 2-4 m up in trees, with all used boxes being on Bulnesia arborea trees.

    Study and other actions tested
  4. A replicated study in 1996-2000 in four tropical forest sites in central Costa Rica (Vaughan et al. 2003) found that scarlet macaws Ara macao successfully hatched eleven clutches from six of 38 (16%) nest boxes provided between 1995 and 2000. Three of these boxes were 1 m plastic barrels (14 erected in total), two were 35 cm PVC tubes (15 erected in total) and one was in a 100 x 60 cm wooden box (nine erected in total). All boxes were erected 10-20 m above the ground in trees. Three clutches were laid in PVC tubes in 2000 were destroyed by monkeys.

    Study and other actions tested
  5. A before-and-after study in western Costa Rica (Vaughan et al. 2005) found an increase in a scarlet macaw Ara macau population from 185-225 individuals in 1990-4 to 225-265 in 1997-2003, following the provision of artificial nests and several other interventions (see ‘Use education programmes and local engagement to reduce pressures on species’, ‘Promote sustainable alternative livelihoods based on species’, and ‘Guard nests to increase nest success’). In 1990-4 the population had been showing a 4%/year decline. This study is discussed in more detail in ‘Increase ‘on-the-ground’ protection to reduce unsustainable levels of exploitation’.

    Study and other actions tested
  6. A replicated study in 1992-2004 in a palm swamp in southeast Peru (Brightsmith & Bravo 2006) found that blue-and-yellow macaws Ara ararauna nested in modified Mauritia palms Mauritia flexuosa, but not in five PVC nest boxes (a pair of scarlet macaws A. macao used one box). A total of 41 palms had their crowns removed over the study period and slowly rotted to produce nesting cavities, with 12 nesting attempts by blue-and-yellow macaws in these cavities. Productivity in 1995 of two pairs of blue-and-yellow macaws and three pairs of red-bellied macaws Orthopsittaca manilata nesting in the palms was comparable to previous estimates for the region (50% success, 0.5 chicks/nest). As palms rotted and productivity declined over time, the authors recommend a rotation system to maintain both the structure of the palm swamp and provide adequate nesting cavities.

    Study and other actions tested
  7. A replicated study in 2004-6 in four tropical montane sites in Colombia (Quevedo et al. 2006) found that four of five threatened parrot species bred and roosted in 240 nest boxes provided. Indigo-winged parrots Hapalopsittaca fuertesi, golden-plumed parakeets Leptosittaca branickii, flame-winged parakeets Pyrhura calliptera and Santa Marta parakeets P. viridicata all used the nest boxes, with an increase in the numbers of young individuals of indigo-winged parrots and golden-plumed parakeets entering natural populations. There was no evidence that rusty-faced parrots H. amazonina used boxes. Boxes were 100 x 25 x 25 cm with a 10-15 cm entrance hole, except for those designed for rusty-faced parrots, which were only 60 cm tall. All boxes had grooves to allow parrots to climb the inside.

    Study and other actions tested
  8. A replicated study in 2006-7 at five montane sites in Colombia (Salaman et al. 2006) found that yellow-eared parrots Ognorhynchus icterotis rarely used artificial nest boxes provided, with one box occupied in 2006 and one in 2007, raising two fledglings each. A total of 42 nest boxes were built and hung 10-20 m above ground on Quindío wax palms Ceroxylum quindiuense lacking suitable nest cavities. Boxes were wooden and hexagonal, with 140 x 20 cm sites and a 10 cm entrance hole, with grooves inside to allow parrots to climb out.

    Study and other actions tested
  9. A replicated study in 1997-2007 in tropical forest in southwest Mauritius (Tatayah et al. 2007) found that the number of echo parakeet Psittacula eques pairs using nest boxes increased from none in 1997-2000 (with two nest boxes available) to 41 in 2006-7 (65 boxes available). In 2006-7, 73% of all parakeet nests (56 nests in total) were in nest boxes, with 71% of these successfully fledging chicks. The nest boxes were wooden, 65 cm high and made from untreated wood with a metal roof and a perch outside. The authors suggest that the number of captive-bred parakeets released into the population may have helped with the uptake of nest boxes, as they were more familiar with artificial structures than wild-bred individuals.

    Study and other actions tested
  10. A replicated study in 2005 at a tropical forest site and nearby ranches in Colombia (Tovar Martinez 2009) studied a subset of the nest boxes used in Quevedo et al. 2006 and found that indigo-winged parrots Hapalopsittaca fuertesi used 13 of 120 nest boxes provided. A total of 39 eggs were laid, 32 (82%) hatched (the remaining seven were infertile) and 25 chicks (78% of those that hatched) fledged. Overall, 10 (91%) nests in boxes successfully fledged one or more chick. The boxes were of the same design as those in Quevedo et al. 2006.

    Study and other actions tested
  11. A replicated study in 2007-2009 (part of a longer study from 2000-2009) in 11 monitored yellow-shouldered parrot Amazona barbadensis nests in tropical forest habitat on Margarita Island, Venezuela (Briceño-Linares et al. 2011) found that artificial nests exhibited low occupancy rates and did not significantly hinder poachers. Of the 12 artificial nests used to supplement existing natural nest, six were used: 1 was used every year, 1 was used in 2007 and 2008, and 4 were used only once (which equated to 25% nest use rate). Moreover, only 40% of the nestlings succeeded in fledgling, the rest being subject to an armed group of poachers raiding the site designated as an assisted breeding program. The artificial nests were made from the preferred natural nesting tree of yellow-shouldered parrots, verawood (Bulnesia arborea). This study is also discussed in ‘Relocate nestlings to reduce poaching’, ‘Use education programmes and local engagement to help reduce pressures on species’, ‘Employ locals as biomonitors’ and ‘Foster eggs or chicks with wild conspecifics’.

    Study and other actions tested
Please cite as:

Williams, D.R., Child, M.F., Dicks, L.V., Ockendon, N., Pople, R.G., Showler, D.A., Walsh, J.C., zu Ermgassen, E.K.H.J. & Sutherland, W.J. (2020) Bird Conservation. Pages 137-281 in: W.J. Sutherland, L.V. Dicks, S.O. Petrovan & R.K. Smith (eds) What Works in Conservation 2020. Open Book Publishers, Cambridge, UK.


Where has this evidence come from?

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Bird Conservation

This Action forms part of the Action Synopsis:

Bird Conservation
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