Collected Evidence: Collected Evidence: Protect nest trees before burning We found no evidence for the effects of protecting nest trees of bird populations before burning. 'No evidence' for an action means we have not yet found any studies that directly and quantitatively tested this action during our systematic journal and report searches. Therefore we have been unable to assess whether or not the action is effective or has any harmful impacts. Please get in touch if you know of such a study for this action.  Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F325https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F325Thu, 26 Jul 2012 16:48:25 +0100Collected Evidence: Collected Evidence: Clear or open patches in forests Of nine studies, seven from the UK and the USA found that early-successional species increased in clearcut areas or opened forests, compared to control areas, areas before management, or other management techniques. One study found that population increases only occurred in clearcuts up to 20 ha in size. Two studies report that mature-forest species declined in cut/opened areas of forest. A replicated, randomised, controlled study from the USA found no differences in species richness between clearcuts of different sizes, whilst another American study found that a mosaic of cut and uncut areas supported a variety of species. A long-term study from the USA of a landscape with opened patches found that there were no consistent differences between clearcut and controlled areas, although some species were only seen in clearcuts.  Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F326https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F326Thu, 26 Jul 2012 16:51:33 +0100Collected Evidence: Collected Evidence: Clearcut and re-seed forests One of two replicated studies from the USA found similar bird densities in clearcut and re-seeded sites as in sites under other managements. A replicated study from the USA found that pine stands replanted with native pines held more scrub-sucessional species than stands managed with tree thinning, midstory tree removal and burning.  Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F327https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F327Thu, 26 Jul 2012 17:11:04 +0100Collected Evidence: Collected Evidence: Coppice trees Of three studies, one, a before-and-after study in the UK found that a population of European nightjars increased following a series of management interventions, including the coppicing of some birch trees. Two before-and-after studies from the UK and the USA found that the use of coppices by some bird species declined over time. The UK study also found that overall species richness decreased with age, but that some species were more abundant in older stands.  Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F329https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F329Fri, 27 Jul 2012 14:58:36 +0100Collected Evidence: Collected Evidence: Manage woodland edges for birds We captured three studies of two experiments, of which one, a before-and-after study from the UK, found an increase in the local population of European nightjars following several management interventions, including the management of woodland edges for birds. Two studies of a replicated, controlled paired sites experiment in the USA found that bird abundances were higher in woodland edges with border-edge cuts and that predation on artificial nests was lower than in uncut edges. Scrub- and edge-nesting species were more abundant. Overall species richness and nest success did not differ different between treatments.  Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F334https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F334Sat, 28 Jul 2012 14:12:39 +0100Collected Evidence: Collected Evidence: Manually control or remove midstorey and ground-level vegetation (including mowing, chaining, cutting etc) in forests Of fifteen studies captured, one, a replicated controlled study from the USA, found higher bird species richness in areas with midstorey thinning, compared to control areas. One study from the USA found similar bird species richness in areas with mid- and understorey control, compared to other management types. A study from Canada found fewer species in treated sites than controls. Seven studies from Europe and the USA found that total bird densities or those of some species or guilds were higher in areas with mid- or understorey management, compared to before management or to areas without management. Four of these studies used understorey removal as part of a wider management regime. Five studies from the USA and Canada found that densities of some species were lower in areas with midi or understorey control, or that overall bird densities did not different between managed and unmanaged areas. Two of these studies investigated several interventions at once. A replicated controlled study from the USA found similar survival for black-chinned hummingbirds in areas with understorey management, compared to areas with other interventions. Two replicated, controlled studies from Canada found higher nest survival in forests with removal of deciduous trees, compared to controls. A controlled study found that northern bobwhite chicks had greater foraging success in areas with cleared understorey vegetation compared to burned areas, but lower than under other managements. A replicated, controlled study from the USA found that midstorey control did not appear to affect competition between species for nesting sites.  Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F335https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F335Sat, 28 Jul 2012 14:20:23 +0100Collected Evidence: Collected Evidence: Remove midstorey from savannasA controlled study in Argentina found that in summer, but not overall, a control area had higher bird abundance and species richness than an area where shrubs were removed. There were also differences in community composition between treatments.  Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F336https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F336Sat, 28 Jul 2012 14:54:45 +0100Collected Evidence: Collected Evidence: Manually control or remove midstorey and ground-level vegetation (including mowing, chaining, cutting etc) in shrubland Of seven studies, one controlled study from the USA, found that overall bird diversity was similar between chained areas, burned areas and controls. A replicated and controlled study from the USA found that overall diversity was lower on mown sites than  controls, but that grassland-specialist species were present on managed sites. Five studies from the USA and Europe found than some study species were found at greater densities or abundances on sites with mechanical vegetation control than on sites with prescribed burning or  no management, or that abundances increased after management. One study investigated several interventions at once. One study from the USA found that total bird densities were similar between chained, burned and control sites. A replicated controlled study from the USA found that mown sites had lower bird abundances than control sites. Three studies from the USA found that some species were less abundant on sites with mechanical vegetation removal, compared with burned or control sites, or showed smaller increases after management. One replicated, controlled study from the USA found no differences between areas cut in winter and those cut in summer.  Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F337https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F337Sat, 28 Jul 2012 14:58:09 +0100Collected Evidence: Collected Evidence: Mow or cut natural grasslands Of six studies, two replicated and controlled studies from the USA found higher densities of birds or nests on mown grasslands, compared to unmanaged or burned areas. Two controlled studies from the USA, one replicated, found lower nesting or population densities of some species, on mown grasslands compared to unmown areas. Two replicated and controlled studies found no significant differences in nesting densities or community composition between mown and unmown areas. One study from the USA found that grasshopper sparrow nesting success was higher on mown areas than grazed areas of grassland. A replicated controlled study from the USA found that ducks had similar nesting success on cut and uncut areas.  Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F338https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F338Sat, 28 Jul 2012 15:41:22 +0100Collected Evidence: Collected Evidence: Mow or cut semi-natural grasslands/pastures Of four studies captured, one, a before-and-after study from the UK, found that local wader populations increased following the annual cutting semi-natural grasslands. A replicated, controlled study from the UK found that ducks grazed at higher densities on cut areas, a second replicated study from the UK found that goose grazing densities were unaffected by cutting frequency. A replicated study from the USA found that Henslow's sparrows were more likely to be recaptured on unmown, compared with mown grasslands.  Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F339https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F339Sat, 28 Jul 2012 15:49:03 +0100Collected Evidence: Collected Evidence: Mow or cut reedbeds Of three studies captured, one controlled study from the Netherlands found that warblers nested at lower densities in cut areas of reeds. Productivity and success did not vary between treatments. An unreplicated study from Denmark found that geese grazed at the highest densities on reedbeds cut 5–12 years previously. One replicated study investigated changing water levels in addition to cutting reeds in the UK and found that management did not affect great bittern breeding productivity but did appear to delay territory establishment.  Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F340https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F340Sat, 28 Jul 2012 20:15:58 +0100Collected Evidence: Collected Evidence: Replace non-native species of tree/shrubA replicated, controlled study from the USA found that the number of black-chinned hummingbird nests increased at sites with fuel reduction and planting of native species, but that the increase was smaller than at sites without planting.  Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F341https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F341Sat, 28 Jul 2012 20:22:33 +0100Collected Evidence: Collected Evidence: Add woody debris to forestsA randomised, replicated, controlled study from Australia found that brown treecreeper numbers were higher in plots with large amounts of dead wood added, compared to control plots or those with less debris added.  Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F344https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F344Sat, 28 Jul 2012 20:38:38 +0100Collected Evidence: Collected Evidence: Remove coarse woody debris from forests One of two replicated and controlled studies from the USA found that overall breeding bird abundance and diversity were lower in plots where woody debris was removed, compared to control plots. Several individually-analysed species showed lower abundances. A replicated, controlled before-and-after study from the USA found lower nest survival for black-chinned hummingbirds following debris removal. Some species in both studies increased after debris removal.  Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F345https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F345Sat, 28 Jul 2012 20:43:34 +0100Collected Evidence: Collected Evidence: Apply herbicide to mid- and understorey vegetation Of seven studies, one replicated, controlled study in forests in Canada found that bird species richness declined after the treatment of deciduous trees with herbicide. Two of the four studies monitoring bird populations (two replicated, controlled before-and-after studies) these found that numbers of red-cockaded woodpeckers or male greater sage grouse increased in all or some herbicide-treated areas. Increases of sage grouse were larger at two areas without vegetation control. One study considered two species: one decreased while the other showed no response. Another found that bird densities increased equally in both control and treatment areas. Three replicated, controlled before-and-after studies in forests found that nest survival was lower where herbicide was applied to exotic shrubs or deciduous vegetation. One study also found lower nesting densities. One controlled study found northern bobwhite chicks higher had foraging success in herbicide-treated forest areas.  Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F346https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F346Sun, 29 Jul 2012 14:17:01 +0100Collected Evidence: Collected Evidence: Employ grazing in natural grasslands Five of 12 studies from the USA and Canada, four replicated, found that some species studied were found at higher densities on grazed than ungrazed sites. Eight studies from the USA, Canada and France, six replicated, found that some or all species studied were found at lower densities on grazed sites compared to ungrazed sites or those under other management, or that there were no differences. Two controlled studies from the USA and Canada, one replicated, found that duck nesting success was higher on grazed than ungrazed sites. Two studies from the USA found that songbird nesting success was lower on grazed than ungrazed sites. Three replicated and controlled (one randomised) studies from the USA and Canada found that grazing had little or no effect on nesting success in a variety of species.  Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F348https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F348Sun, 29 Jul 2012 14:35:22 +0100Collected Evidence: Collected Evidence: Employ grazing in artificial grasslands/pastures Of ten studies captured, one replicated, controlled study from the USA found lower species richness in grazed areas than ungrazed. Another replicated, controlled study from the USA found no consistent differences in community composition between grazed and ungrazed areas. A small study from Canada found an increase in duck populations following the start of grazing amongst other interventions. Five studies from the UK and USA, four replicated, found higher use of, or higher nesting densities in, grazed areas compared to ungrazed. Seven studies from the UK, Canada and the USA, five replicated, found no differences in use or nesting densities, or lower abundances of birds on grazed, compared with ungrazed areas. One found that several species appeared to be excluded by grazing. Three studies from the UK, USA and Canada, two replicated, found that nesting success or productivity was similar, or lower, on grazed sites compared with ungrazed.  Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F349https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F349Sun, 29 Jul 2012 14:59:09 +0100Collected Evidence: Collected Evidence: Employ grazing in non-grassland habitats One of eight studies, a replicated, controlled study on savannas in Kenya found more bird species on grazed site, compared with unmanaged sites. These differences were not present during drought years. A before-and-after study from the Netherlands found the number of species in a mixed habitat wetland site declined after the number of grazing animals increased. Three studies (two replicated) from a variety of habitats in Sweden, the Netherlands and Kenya found that the overall number of birds, or the densities of some species were higher in grazed than ungrazed sites, or increased after the introduction of grazing. The Kenyan study found differences were not present in drought years. Four studies from several habitats in Europe and Kenya found that some species were found at lower densities, or not found at all, on grazed sites compared to ungrazed sites or those under different management. Five studies from several habitats from across the world found no differences in the abundances or densities of some or all species between grazed sites and those that were ungrazed or under different management. Two replicated studies from the UK found that productivity of northern lapwing and grey partridge was lower in grazed sites compared to ungrazed. One study examined several interventions at the same time. A replicated study from the UK found that songbirds and invertebrate-eating species were more common on rough-grazed habitats than intensive pasture, but that crows were less so.  Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F350https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F350Sun, 29 Jul 2012 15:22:08 +0100Collected Evidence: Collected Evidence: Plant trees to act as windbreaks One of two before-and-after studies, from the UK, found that the local population of European nightjars increased following several interventions including the planting of windbreaks. A before-and-after study, from the USA, found that erecting a windbreak appeared to disrupt lekking behaviour in greater prairie chicken territories nearby.  Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F351https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F351Sun, 29 Jul 2012 15:42:39 +0100Collected Evidence: Collected Evidence: Re-seed grasslands One of two studies, both from the UK and investigating grazing by geese Branta spp., found that geese grazed at higher densities on grasslands that were re-seeded, compared to control or fertilised areas. One study found that areas sown with clover were grazed at higher densities than those sown with grass seed.  Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F352https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F352Sun, 29 Jul 2012 15:46:04 +0100Collected Evidence: Collected Evidence: Fertilize artificial grasslands We captured four studies examining the impacts of fertilizing grasslands, all from the UK and investigating grazing by geese Anser and Branta spp. Two studies found that more geese grazed on areas that were fertilised compared with control areas. Two studies found that cut and fertilised areas were used more than control areas. One study found that fertilised areas were used less than re-seeded grasslands. One study found that fertilisation affected grazing at applications of 50 kg N/ha, but not 18 kg N/ha. One study found that grazing rates only increased with applications of up to 80 kg.N/ha.  Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F353https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F353Sun, 29 Jul 2012 16:06:25 +0100Collected Evidence: Collected Evidence: Raise water levels in ditches or grassland Of seven studies captured, one, a before-and-after study from the UK found that two wader species recolonised a site after water levels were raised. A third was found at very high levels. A review from the UK found that high-level agri-environment schemes designed to provide wet habitats were effective at providing habitats for waders and two replicated studies from the UK and Denmark found that northern lapwings were more likely to nest or nested at higher numbers on grasslands with high water levels. A replicated and controlled study from Denmark found that Eurasian oystercatchers did not nest at higher densities on fields with raised water levels and that raising water levels had no effect on nesting on restored grassland fields. A replicated study from the USA found that predation rate on Cape Sable seaside sparrow nests increased as water levels increased. A replicated, controlled and paired sites study from the UK found that birds visited grassland sites with raised water levels at higher rates than other fields. A replicated study from the UK found no differences in feeding rates on sites with raised water levels, compared with control sites.  Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F354https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F354Sun, 29 Jul 2012 16:25:13 +0100Collected Evidence: Collected Evidence: Manage water level in wetlands Of six studies, one replicated, controlled study from the USA found that bird diversity was affected by maintaining water levels at different levels. A study from the USA found that ducks were more abundant when high water levels were maintained on a wetland site. Geese were more abundant when lower levels were maintained. Three studies from the USA and Canada, two replicated, found that different species showed preferences for different water levels in wetlands. A replicated study from the UK found that great bitterns established territories earlier when deep water levels were maintained, but this had no effect on productivity. A review from Spain found that management successfully maintained water near a greater flamingo nesting area, but the effects of this were not measured.  Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F355https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F355Sun, 29 Jul 2012 16:49:45 +0100Collected Evidence: Collected Evidence: Plough habitats One of four studies (of two experiments), from the USA, found that bird densities were higher on ploughed wetland areas, compared to unploughed areas. Three studies of a site comparison study from the UK found that few whimbrels nested on ploughed and re-seeded areas of heathland, but these areas were used for foraging in early spring. There were no differences in chick survival between birds that used ploughed and re-seeded heathland and those that did not.  Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F358https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F358Sun, 29 Jul 2012 17:05:56 +0100Collected Evidence: Collected Evidence: Create scrapes and pools in wetlands and wet grasslands Of six studies captured, four before-and after studies from the UK and North America found that the use of sites, or the breeding population of birds on sites, increased following the creation of ponds and scrapes or was higher in areas with ditch-fed ponds. A study from the USA found that dabbling ducks used newly-created ponds in large numbers, although other species preferred older ponds. Songbirds did not appear to be affected by pond-creation. A replicated site from the UK found that northern lapwing chicks foraged in newly created wet features and that chick condition was higher in sites with a large number of footdrains.  Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F359https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F359Sun, 29 Jul 2012 17:26:31 +0100
What Works 2021 cover

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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