Collected Evidence: Collected Evidence: Provide artificial nesting sites for owls Three studies from the UK appeared to show increases in local populations of owls following the installation of artificial nests, although the authors from one note that they could not rule out birds merely switching from natural nest sites. Another UK study found that providing nesting sites when renovating buildings maintained barn owl Tyto alba populations, whilst they declined at sites without nests. Four studies from the USA and the UK found high levels of breeding success in artificial nests, three finding equal or higher productivity than natural nests. A replicated, controlled study from the USA found lower productivity from artificial nests, whilst a replicated, controlled study from Finland found that artificial nests were only successful in the absence of larger owls and a replicated, controlled study from Hungary found that fledglings from artificial nests were less likely to be found alive after one year. Four studies from the USA and Europe found that artificial nests were used at least as frequently as natural nesting sites. Five studies from across the world found that owls used artificial nests, with one finding that use increased over time, although only for one of two species. Three studies found that owls differentiated between nests in different positions, whilst five studies found that different designs of nests differed in occupancy or productivity. Three studies found occupancy did not differ between designs and two found no differences in productivity for different designs.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F490https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F490Mon, 03 Sep 2012 15:06:04 +0100Collected Evidence: Collected Evidence: Provide artificial nesting sites for oilbirdsA before-and after-study in Trinidad and Tobago found an increase in size of an oilbird colony following the creation of artificial nesting ledges.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F491https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F491Mon, 03 Sep 2012 16:25:31 +0100Collected Evidence: Collected Evidence: Provide artificial nesting sites for pigeonsTwo replicated studies from the USA and the Netherlands found high use rates and high nesting success of pigeons and doves using artificial nests.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F492https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F492Mon, 03 Sep 2012 16:47:27 +0100Collected Evidence: Collected Evidence: Provide artificial nesting sites for trogonsA small study from Guatemala found that at least one resplendent quetzal Pharomachrus mocinno nested in nest boxes provided.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F493https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F493Mon, 03 Sep 2012 16:55:55 +0100Collected Evidence: Collected Evidence: Provide artificial nesting sites for rollers A before-and-after study from Spain found that the use of nest boxes by European rollers Coracias garrulous increased over time and that use varied between habitats. A replicated controlled trial from Spain found no difference in success rates between new and old nest boxes, although birds in old boxes began nesting earlier.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F494https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F494Mon, 03 Sep 2012 17:06:54 +0100Collected Evidence: Collected Evidence: Provide artificial nesting sites for swiftsA study from the USA found that Vaux’s swifts Chaetura vauxi successfully used nest boxes provided.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F495https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F495Tue, 04 Sep 2012 12:42:04 +0100Collected Evidence: Collected Evidence: Provide artificial nesting sites for woodpeckers Four studies from the USA found local increases in red-cockaded woodpecker Picoides borealis populations or the successful colonisation of new areas following the installation of ‘cavity inserts’ (described above). One study also found that the productivity of birds using the inserts was significantly higher than the regional average. Two studies from the USA found that red-cockaded woodpeckers Picoides borealis used cavity inserts, in one case more frequently than making their own holes or using natural cavities. One study from the USA found that woodpeckers roosted, but did not nest, frequently in nest boxes. Five studies from the USA found that some woodpeckers excavated holes in artificial snags but only ever roosted in excavated holes or in nest boxes provided. A small study in the USA found that modifying artificial nests to allow easy access did not alter the behaviour of birds using them.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F496https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F496Tue, 04 Sep 2012 12:45:28 +0100Collected Evidence: Collected Evidence: Provide artificial nesting sites for parrots 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.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F497https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F497Tue, 04 Sep 2012 13:10:55 +0100Collected Evidence: Collected Evidence: Provide artificial nesting sites for songbirds Only three studies out of 66 from across the world found low rates of nest box occupancy, although this may be partially the result of publishing biases. Thrushes, crows, swallows and New World warblers were the target species with low rates of use. Thrushes, crows, finches, swallows, wrens, tits, Old World and tyrant flycatchers, New World blackbirds, sparrows, waxbills, starlings and ovenbirds all used nest boxes. One study from the USA found that wrens used nest boxes more frequently than natural cavities. Five studies from across the world found higher population densities or population growth rates in areas with nest boxes, whilst one study from the USA found higher species richness in areas with nest boxes. One study from Chile found that breeding populations (but not non-breeding populations) were higher for two species when next boxes were provided. Twelve studies from across the world found that productivity of birds in nest boxes was higher or similar to those in natural nests. One study found there were more nesting attempts in areas with more nest boxes, although a study from Canada found no differences in behaviour or productivity between areas with high or low densities of nest boxes. Two studies from Europe found lower predation of some species using nest boxes. However, three studies from the USA found low production in nest boxes, either in absolute terms or relative to natural nests. Thirteen studies from across the world founds that use, productivity or usurpation varied with nest box design, whilst seven found no difference in occupation rates or success with different designs. Similarly, fourteen studies found different occupation or success rates depending on the position or orientation of artificial nest sites. Two studies found no difference in success with different positions.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F498https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F498Tue, 04 Sep 2012 13:52:37 +0100Collected Evidence: Collected Evidence: Clean nest boxes to increase occupancy or reproductive success Five studies from Spain and North America found that various songbirds preferentially nested in cleaned nest boxes, compared to used ones. One study from the USA found that eastern bluebirds showed this preference, but most did not switch from a soiled to a cleaned nest box. One study from the USA found that birds showed an avoidance of heavily-soiled boxes and one from Canada found that tree swallows Tachycineta bicolor preferentially selected nests which were sterilised by microwaving. Two studies from the USA found that eastern bluebirds Sialia sialis and house wrens Troglodytes aedon preferentially nested in uncleaned nest boxes, and one study found that prothonotary warblers Protonotaria citrea showed no preference for cleaned or uncleaned boxes. None of the five studies that investigated it found any difference in success or parasitism levels between cleaned and uncleaned nest boxes.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F499https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F499Tue, 04 Sep 2012 16:10:03 +0100Collected Evidence: Collected Evidence: Use differently-coloured artificial nestsA replicated study from the USA found that two species showed different colour preferences for nest boxes, but that in each case, the preferred colour had lower nesting success than the less preferred colour.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F500https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F500Tue, 04 Sep 2012 16:21:30 +0100Collected Evidence: Collected Evidence: Provide nesting material for wild birds A replicated study in the UK found that songbirds used feathers provided at a very low rate and nest construction did not appear to be resource limited. A replicated, controlled study from Australia found that four species of egrets used supplementary nesting material provided, preferentially taking material from raised platforms over water compared to plots on dry land.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F501https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F501Tue, 04 Sep 2012 16:23:14 +0100Collected Evidence: Collected Evidence: Repair/support nests to support breedingA small study from Puerto Rico found that nine Puerto Rican parrot Amazona vittata nests were repaired, resulting in no chicks dying of cold.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F502https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F502Tue, 04 Sep 2012 16:31:27 +0100Collected Evidence: Collected Evidence: Artificially incubate eggs or warm nests A replicated, controlled trial in the UK found that great tits Parus major were less likely to interrupt their laying sequence if their nest box was heated, although there was no effect on egg or clutch size. A small study in New Zealand found that no kakapo Strigopus habroptilus eggs or chicks died from chilling following the use of nest warmers. Before this a nest had been lost to chilling.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F503https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F503Tue, 04 Sep 2012 16:34:31 +0100Collected Evidence: Collected Evidence: Provide nesting habitat for birds that is safe from extreme weather A small from New Zealand found Chatham Island oystercatchers Haematopus chathamensis used raised nest platforms made from car tyres (designed to raise nests above the level of storm surges). The success of these nests is not reported. Two replicated, controlled studies from the USA found that the nesting success of terns and waders was no higher on specially raised areas of nesting substrate, compared to unraised areas, with one study finding that a similar proportion of nests were lost to flooding in raised and unraised areas.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F504https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F504Thu, 06 Sep 2012 13:55:55 +0100Collected Evidence: Collected Evidence: Remove vegetation to create nesting areas Two out of six studies found that the number of waders and terns nesting in an area increased following the removal of vegetation, and another found that a tern colony moved to an area prepared by removing vegetation. Two of these studies used multiple interventions at once. One study found a decrease in colony size after several interventions, including vegetation control. A study from the UK found that gulls and terns nested in an area cleared of vegetation and a controlled study from Puerto Rico found that although no terns nested in plots cleared completely of vegetation, more nested in partially-cleared plots than in uncleared plots. A before-and-after study from Canada found that tern nesting success was higher after plots were cleared of vegetation and other interventions were used.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F505https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F505Thu, 06 Sep 2012 14:00:49 +0100Collected Evidence: Collected Evidence: Guard nests to increase nest success A before-and-after study from Costa Rica found an increase in scarlet macaw Ara macau population following the monitoring of nests, along with several other interventions. Two studies from Puerto Rico and New Zealand found that parrot nest success was higher or mortality reduced or nest success higher with intensive monitoring of nests, ompared to periods without monitoring. A study from New Zealand also found high overall nest success when nests were monitored.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F506https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F506Thu, 06 Sep 2012 14:12:26 +0100Collected Evidence: Collected Evidence: Foster eggs or chicks of gannets and boobies with wild conspecificsA small controlled study in Australia found that Australasian gannet chicks Morus serrator were lighter, and hatching and fledging success lower in nests which had an additional egg or chick added. However, overall productivity was (non-significantly) higher in experimental nests.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F507https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F507Thu, 06 Sep 2012 14:17:32 +0100Collected Evidence: Collected Evidence: Foster eggs or chicks of waders with wild conspecifics Two small trials in North America found that piping plovers Charadrius melodus accepted chicks introduced into their broods, although in one case the chick died later the same day. A replicated study from New Zealand found that survival of fostered black stilts Himantopus novasezelandiae was higher for birds fostered to conspecifics rather than a closely related species.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F508https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F508Thu, 06 Sep 2012 14:30:39 +0100Collected Evidence: Collected Evidence: Foster eggs or chicks of vultures with wild conspecificsTwo small studies, one a New World vulture and one of an Old World species found that single chicks were successfully adopted by foster conspecifics, although in one case this led to the death of one of the foster parents’ chicks.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F509https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F509Thu, 06 Sep 2012 14:34:30 +0100Collected Evidence: Collected Evidence: Foster eggs or chicks of raptors with wild conspecifics Ten out of 11 studies from across the world found that fostering raptor chicks to wild conspecifics had high success rates. A single study from the USA found that only one of six eggs fostered to wild bald eagle Haliaeetus leucocephalus nests were hatched and raised. The authors suggest that the other eggs may have been infertile. A replicated study from Spain found that Spanish imperial eagle Aquila adalberti chicks were no more likely to survive to fledging if they were transferred to foster nests from three chick broods (at high risk from siblicide), compared to chicks left in three-chick broods. A replicated study from Spain found that young (15–20 years old) Montagu's harrier Circus pygargus chicks were successfully adopted, but three older (27–29 day old) chicks were rejected.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F510https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F510Thu, 06 Sep 2012 14:42:31 +0100Collected Evidence: Collected Evidence: Foster eggs or chicks of owls with wild conspecifics A replicated study in the USA found high fledging rates for barn owl Tyto alba chicks fostered to wild pairs. A replicated controlled study from Canada found that captive-reared burrowing owl Athene cunicularia chicks fostered to wild nests did not have significantly lower survival or growth rates than wild chicks.    Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F511https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F511Thu, 06 Sep 2012 15:57:35 +0100Collected Evidence: Collected Evidence: Foster eggs or chicks of cranes with wild conspecificsA small study in Canada found high rates of fledging for whooping crane Grus americana eggs fostered to first time breeders (which normally have very low fertility).  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F512https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F512Thu, 06 Sep 2012 16:13:08 +0100Collected Evidence: Collected Evidence: Foster eggs or chicks of bustards with wild conspecificsA small study in Saudi Arabia found that a captive-bred egg was successfully fostered to a female in the wild.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F513https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F513Thu, 06 Sep 2012 16:18:42 +0100Collected Evidence: Collected Evidence: Foster eggs or chicks of woodpeckers with wild conspecifics Three studies from the USA found that red-cockaded woodpecker Picoides borealis chicks fostered to conspecifics had high fledging rates. One small study found that fostered chicks survived better than chicks translocated with their parents.    Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F514https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F514Thu, 06 Sep 2012 16:29:20 +0100
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What Works in Conservation

What Works in Conservation provides expert assessments of the effectiveness of actions, based on summarised evidence, in synopses. Subjects covered so far include amphibians, birds, mammals, forests, peatland and control of freshwater invasive species. More are in progress.

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