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Providing evidence to improve practice

The journal, Conservation Evidence

Our online journal publishes research, monitoring results and case studies on the effects of conservation interventions. All papers include some monitoring of the effects of the intervention and are written by, or in partnership with, those who did the conservation work. It includes interventions such as habitat creation, habitat restoration, translocations, reintroductions, invasive species control, and education or integrated conservation development programmes, from anywhere around the world.

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A volume is created each year with peer-reviewed papers published throughout the year. We now accept Short Communications as well as standard papers.

Special issues contain new papers on a specific topic.

Virtual collections collate papers published in the journal on specific topics such as management of particular groups of species.

To search for papers on a specific topic within the journal select Advanced search, enter your keyword(s) and within the Source box type: "conservation evidence". This will take you to a list of actions that contain Conservation Evidence papers. In order to see the list of individual Conservation Evidence papers on the topic, please click on 'You can also search Individual Studies' at the top of this page.

Bird Management

To mark the publication of Bird Conservation: Evidence for the Effects of Interventions, we produced two virtual collections. The first was on bird reintroductions. This collection now contains 53 Conservation Evidence papers on bird management.

The red-footed falcon is a near threatened species, which breeds mainly in agricultural landscapes, typically nesting in empty corvid nests on trees. In Europe, this species is declining due to habitat degradation and agriculture intensification. The aim of our study was to determine the reproductive success and the increase in the number of nesting pairs after the installation of nest boxes. This study took place in the Italian province of Parma, the southernmost part of the red-footed falcon’s breeding range. Nest boxes were provided in four locations, where falcons were already breeding in corvid nests, to assess if this action could increase the falcon population and breeding success in the study area. After the deployment of 117 nest boxes from 2010 to 2018 the Parma population increased from 25 to 82 pairs, occupying up to 50% of available boxes in 2018. The breeding success remained unvaried over the study period with an average of 2.06 and 2.37 chicks fledged per pair in corvid nests and nest boxes respectively. It also did not differ between the two nest categories. These results could indicate that a lack of suitable nesting sites is a major limiting factor for the falcon population in the Parma province rather than lack of food.

Common swifts Apus apus have shown significant declines in the UK over recent decades, and one possible cause is loss of nesting sites. Nest boxes have previously shown to be effective for this species. Here we test whether the addition of an artificial ‘nest form’ affected the occupancy of nest boxes. Nest boxes that contained a form were 4.6 times more likely to be occupied by common swifts than nest boxes without a form. The design of the form did not appear to affect occupancy rate. Further study is needed to discover whether nest forms increase overall occupancy rates.

A simple predator exclosure applied to saffron-cowled blackbird nests resulted in 69% fledging success compared to 36% for the controls.

We conducted a trial of a mitigation technique aimed at reducing avian electrocution rates at a 15kV electricity distribution line in the Mongolian steppe. Electrocution resulted from birds contacting live conductor cables either when perched at the top of the grounded steel-reinforced concrete pole or when perched on the steel crossarm. Mitigation focused on line poles and involved creating a barrier between the live conductors and perch sites at randomly selected poles. This involved attaching the pin insulator at the top of the pole with a new mount, so that it was repositioned centrally to discourage birds from perching on top of the pole, while additional unconnected pin insulators were affixed adjacent to those supporting the conductor cables on the crossarm to provide a barrier to birds touching the live cables. Electrocution rates were significantly lower at mitigated poles compared to control poles, with an average reduction of 85%. This mitigation technique is relatively inexpensive to implement (approximately US$12/pole for materials), with no additional maintenance requirement and a life expectancy similar to that of the base pole design. While not eliminating electrocution risk, this mitigation technique may be useful in circumstances where the cost of implementation and sustained maintenance largely determines whether or not any form of mitigation is undertaken.

Understanding factors causing the low breeding success of capercaillies Tetrao urogallus is important for the conservation of this species. Here we investigate possible causes of spatial variation in breeding success in two neighbouring Scots pine Pinus sylvestris woods in Scotland, Abernethy Forest and Craigmore Wood. Breeding success declined with increasing June rainfall at both sites, but there was a stronger effect at Abernethy. Average productivity (chicks/female) during 2000-2011 was 1.61 (95% C.I. 1.08-2.41) times greater at Craigmore than Abernethy. It was possible that the difference was due to increased wetting of chicks by vegetation during and after rain at Abernethy, where the vertical density of the shrub and grass layer was greater than at Craigmore. Wet chicks may then die. To test this hypothesis, 2 m wide routes were cut through tall heather Calluna vulgaris at Abernethy, so that broods could move between bilberry Vaccinium myrtillus feeding areas without having to brush against tall dense vegetation. However, there was no improvement in breeding success in the treated area compared to a control area. Possible explanations are that the capercaillies did not use the cut routes, that cutting did not provide sufficiently short vegetation, that rain affects capercaillie chicks in other ways (e.g. through insect availability), or that broods shelter from rain using pine thickets.


The Pen y Cymoedd windfarm in South Wales, UK, is set in an upland area currently dominated by coniferous forestry with a varied age structure resulting from standard forestry management practices. The site supports an important population of European nightjar Caprimulgus europaeus. The activities associated with wind farm construction have the potential to damage and disturb nightjar nests during the breeding season whilst long term operation has the potential for collision mortality. To mitigate for potential impacts during construction, we implemented measures to allow nest avoidance including the identification and demarcation of active nest sites. Due to the difficulty in locating nightjar nests and the potential for false negative results, additional measures were deployed at 17 turbine locations to deter nightjars from establishing nesting territories. Deterrent measures involved regular removal of vegetation on the construction areas. We tested the effectiveness of the deterrent measures by comparing levels of male nightjar territorial display activity in treated and untreated locations over one breeding season. Territorial behaviour was recorded using standard nightjar presence-absence survey methods. We found no significant difference between levels of territorial display activity in treated and untreated areas. This suggests that the deterrent measures utilised at Pen y Cymoedd in 2016 were ineffective in deterring male nightjar display activity during windfarm construction.

We monitored 100 artificial nests of four different designs to examine the occupancy and breeding success of predatory birds in nest site limited, steppe habitat of central Mongolia. Three species, upland buzzard Buteo hemilasius, common raven Corvus corax and saker falcon Falco cherrug occupied artificial nests in all years and their number increased over the five-year study period, when the number of breeding predatory birds rose from 0 to 64 pairs in our 324 km2 study area. The number of breeding pairs of saker falcons increased at a faster rate than ravens, reflecting their social dominance. Saker falcons and common ravens preferred to breed inside closed-box artificial nests with a roof, whereas upland buzzards preferred open-top nests. For saker falcons nest survival was higher in closed nests than open nests but there was no significant difference in laying date, clutch size and brood size in relation to nest design. This study demonstrates that whilst nest boxes can increase breeding populations in nest site limited habitats, nest design may also influence occupancy rates and breeding productivity of the species utilizing them. Careful consideration is needed in designing nests to maximize occupancy rates and productivity.


Colony guardian programme improves recruitment in the critically endangered hooded grebe Podiceps gallardoi in Austral Patagonia, Argentina
Roesler I., Fasola L., Casañas H., Hernández P.M., de Miguel A., Giusti M.E. & Reboreda J.C. (2016), 13, 62-66

The critically endangered hooded grebe Podiceps gallardoi has suffered a population reduction of 80% in the last 25 years. Although climatic conditions are suggested to be important causes of this decline, invasive species are also having a large impact. Hooded grebes have the lowest recruitment rate within the Podicepodiformes, but this is usually compensated by high adult survival. Considering these life history traits and threats, we designed the ‘colony guardian programme’, which aimed to protect nesting grebes by reducing the negative impacts of American mink and kelp gull on breeding colonies of grebes in central-western Santa Cruz Province, Argentina. Over five breeding seasons between 2011 and 2015, 10 colonies were protected using a total of 755 fieldwork days. Colonies guarded throughout the breeding season had higher recruitment (0.64 juveniles/breeding pair) than colonies with little or no protection (0.39 juveniles/breeding pair).


Metal fence removal improved survival of a nocturnal seabird on Isla Natividad, Mexico
Albores-Barajas Y.V., Soldatini C., Ramos-Rodriguez A. & Dell'Omo G. (2016), 13, 67-71

The black-vented shearwater Puffinus opisthomelas is endemic to Mexico and is currently listed as Near Threatened by the IUCN Red List. Ninety-five percent of the world population of the species breeds on a single island in Mexico, Isla Natividad. In 2014 a metal fence was placed on the perimeter of the island landfill site to prevent wind-blown garbage dispersal. The fence was close to the black-vented shearwater colony and we found 116 shearwater carcasses during our first survey in the area. Using thermal cameras, we assessed the harm caused by the fence to the bird population as between six and seven birds/night. After discussion with local stakeholders the fence was removed in April 2016. Since then no more carcasses of black-vented shearwaters were found in the area. These results demonstrate that such structures can have dramatic effects on the survival of nocturnal seabirds and should be avoided, particularly in the vicinity of colonies. This was an example of positive collaboration with the local community and the application of research results to reserve management.


Possum control and bird recovery in an urban landscape, New Zealand
Johnstone Macleod L., Dickson R., Leckie C., Stephenson B.M. & Glen A. S. (2015), 12, 44-47

In New Zealand invasive brushtail possums Trichosurus vulpecula reduce nesting success of native birds and compete with them for food. As an urban biodiversity initiative, intensive possum control was carried out in a residential area on Napier Hill, North Island. Bird species were monitored using  five-minute point counts, conducted once before the possum control programme and then annually for a further five years afterwards. Significant increases in the relative abundance of bellbird Anthornis melanura and tui Prosthemadera novaeseelandiae were attributed to an increase in food supply due to reduced competiton from possums. Kereru Hemiphaga novaeseelandiae numbers remained relatively stable and a significant decline was recorded in the relative abundance of silvereyes Zosterops lateralis. Management of possum populations will be continued to try to further improve native bird abundance on Napier Hill.


Changes were made to the management of moorland and adjacent in-bye land at the Royal Society for the Protection of Birds' Lake Vyrnwy reserve in Wales with the aim of improving breeding habitat for Eurasian curlew Numenius arquata. Areas of tall, rank, moorland vegetation were cut to provide a mosaic of short areas for foraging and taller areas for nesting habitat. Some new moorland pools were also created, and enclosed improved grassland was managed with the aim of reducing compaction and improving invertebrate levels. The initial response of the breeding curlew population was encouraging but short-lived, although the population has remained at a slightly higher level than before the management was carried out.


Although guano from nesting seabirds is known to fertilize vegetation in nesting colonies, resulting in increased vegetation height and cover, little published research addresses the loss of nesting habitat that may result from this overgrowth. Terns, which nest in limited areas of predator-free, undeveloped coastal habitat, are especially vulnerable to nesting habitat loss due to vegetation overgrowth, but very little information in the scientific literature is applicable to management efforts in seabird nesting habitat. I gathered information on vegetation management effort and success at tern nesting colonies from a survey of colony managers throughout the temperate North Atlantic, as well as from published and unpublished literature. I identified twelve applicable techniques in three categories: vegetation control during the period of plant growth, vegetation control prior to the period of plant growth, and habitat construction. Although the effectiveness of all techniques varied widely across locations and application methods, habitat construction techniques were the most likely to provide nesting habitat for a full season without vegetation re-growth. I summarize general factors likely to influence the effectiveness of management efforts and offer guidelines for choosing different techniques for managing vegetation.


The provision of nest-boxes was tested as a low cost method to increase fledging success in the rifleman Acanthisitta chloris, a declining endemic New Zealand species that is at risk from introduced mammalian predators. Nest success of riflemen in nest-boxes (80%) was five times higher than those in natural nest sites (16%). This difference was due to a reduction in the rate of predation in nest-boxes. However, aluminium nest guards did not further increase nest success in nest-boxes (82%). This outcome indicates that nest-boxes can provide a low cost and non-lethal method to protect rifleman nests from predators and increase fledging productivity.

The use of helicopters for spreading bait pellets in rodent eradication operations for conservation programmes is increasing. While aerial applications generally have a high success rate at eradicating rodents, operations that tackle extensive areas of steep terrain (slopes >50°) are more challenging, as the effectiveness of spreading bait pellets at the targeted density in these areas is unknown. We undertook an aerial baiting trial on Gough Island, where predation by the non-native house mouse Mus musculus is devastating the globally important seabird populations. It is therefore critical to deliver bait to the island’s large areas of vegetated cliffs that contain burrowing petrels and mice. Using a helicopter and bait hopper we spread non-toxic bait pellets on two areas of coastal cliffs and the adjoining flat ground, and measured the resulting density of pellets using teams of roped climbers and distance sampling. Compared with adjacent flat areas, the vegetated cliff areas retained an average 66-76% of pellets (lower 95% confidence interval 45-60%). While baiting rates on cliffs were lower than adjoining flat areas, the recommended best practice for aerial eradications prescribes applying two additional drops on steep areas. Consequently, current best practice would be sufficient to ensure coverage at densities at or above the targeted baiting rate. While these trials were focused on Gough Island, the results should be useful for eradication operations on other islands with cliffs with similar terrain and vegetation cover.

The breeding success of obligate secondary cavity nesting birds, including most parrots, can be limited by the availability and quality of nest cavities. Habitat degradation can reduce the number of large cavity-containing trees. This reduction in available cavities can be exacerbated by destructive nest poaching practices, which leave cavities damaged and unusable. Yellow-shouldered Amazons Amazona barbadensis inhabit degraded dry-forest areas on the island of Bonaire (Caribbean Netherlands), and were suspected to be limited by the number of suitable nesting cavities. We compared two approaches to increasing the availability of nesting sites, measuring occupation rates of 10 nest boxes and 10 repaired natural cavities over three years. While none of the nest boxes were used, two of the restored cavities were occupied within five months of repair, and a third in the following year. Only one of the breeding attempts in restored cavities (33%) was successful, compared to the population average of 56%. Sample sizes are small, but restoring natural nest cavities led to a higher rate of uptake than nest boxes and was a considerably quicker and cheaper intervention. However the effectiveness of this intervention depends on the threat of poaching, and there is a risk that restoring poacher-damaged nests may attract breeding pairs away from safer cavities.

A former military airfield at Orford Ness had naturally developed into a coastal grazing marsh, but limited water control and high evaporation caused it to be highly prone to drying out in summer. With the intention of attracting higher numbers of breeding waders, six large shallow pools and two deeper ponds were created by building low bunds linked by new ditches and water control points. To replace water losses to evapotranspiration, new sluices were built into the river walls to allow estuary water to be drawn into two new lagoons at high tide, and from there into the ditches and pools to maintain desired water levels. The number of breeding waders in the modified areas increased from an average of eight pairs in the two years prior to the works to 23 pairs in the year after the creation of pools. Pied avocet numbers increased from zero to five pairs, common redshank from five to 13 pairs, and northern lapwing from three to five pairs.

A former military airfield at Orford Ness had naturally developed into a coastal grazing marsh, but limited water control caused it to be deeply flooded in winter. With the intention of attracting higher numbers of waders, six large pools were created with low bunds each surrounded by shallower water and linked by new ditches and water control points. A new water pump was installed to enable excess rainwater to be evacuated into the adjacent estuary. The number of wintering waders in the modified areas increased tenfold in mid-winter from pre to post-works, and the waders showed increased use of areas that had become shallowly, rather than deeply, flooded. The rise in wader numbers was not due to within-site movement, as an adjacent, unmodified marsh showed no change in bird numbers. Late summer wader numbers, which may include passage migrants, were 2.5 times higher after the management work.

Increase of white stork Ciconia ciconia population attracted by artificial nesting platforms in Calabria, Italy
Santopaolo R., Godino G., Golia S., Mancuso A., Monterosso G., Pucci M., Santopaolo F. & Gustin M. (2013), 10, 67-69

Between 2002 and 2012, the return of breeding pairs of white storks to Calabria, Italy, was encouraged through the installation of 46 artificial circular wooden platforms, of which 35 were supported on masts, nine on utility poles, and two on iron poles. The first platform nest was built in 2007, when there were just three breeding pairs of white storks at the site. By 2012, eleven nests were on artificial platforms, and the total white stork population at these sites had risen to 12 pairs. Between 2007 and 2012, 103 juveniles fledged from 30 nests located on platforms. More young fledged from nests on artificial platforms (4.0 ± 1.0 per nest), than from nests located elsewhere (3.4 ± 0.9 per nest). These results show that artificial platforms installed in suitable areas can be an effective in helping to increase breeding populations of white storks.


In New Zealand, invasive non-native mammals threaten the survival of native species such as the North Island brown kiwi (Apteryx mantelli). At Whangarei Heads, in northern New Zealand, community groups are working with local and national government agencies to protect kiwi populations. The abundance of kiwi there has been monitored since 2001 using annual counts of calls. Trapping of invasive mammals began in 2002, and their relative abundance is assessed from annual capture rates. Capture rates of stoats (Mustela erminea), weasels (M. nivalis), cats (Felis catus), rats (Rattus spp.) and possums (Trichosurus vulpecula) have declined significantly since trapping began, suggesting their abundance has been suppressed. Ferrets (Mustela furo) were already scarce when trapping began, and have been reduced to undetectable levels in most years. Numbers of hedgehogs (Erinaceus europaeus) have shown little response to trapping. Kiwi populations were apparently in decline before pest control began, but have since increased. Kiwi call rates in 2011 were the highest so far recorded at Whangarei Heads. Stoats are considered one of the main threats to kiwi, and our data suggest that kiwi numbers remain low unless stoat abundance is reduced below a catch per unit effort threshold of ~0.1 stoat per trap per year.

The White-winged Nightjar Eleothreptus candicans is a globally threatened nightbird of the open savannas of central South America. Previous observations, suggesting that the species has a preference for recently burnt habitats, have potentially been confounded by the increased detectability of individuals and the lack of availability of unburnt habitats following extensive wildfires. This study attempted to address these limitations by monitoring the response of three radio-tagged nightjars (which had already been tracked for ≥10 months) to an experimental burn, overlapping with 16–33% of their pre-burn home ranges, at Bosque Mbaracayú Biosphere Reserve in eastern Paraguay. Overall, 10 (24%) of the 42 nocturnal radio-tracking fixes obtained during eight weeks of post-burn monitoring were within the burnt area. One individual entirely avoided the burn parcel following the burn, but the other two showed no significant preference for the burnt area. None of the seven diurnal roost sites located during post-burn monitoring was within the burn parcel. This apparent lack of an active preference for burnt habitat, at least during the first two months immediately following a fire, adds weight to recommendations for more active fire management in the few protected areas where the species persists, in order to reduce the frequency of the periodic uncontrollable and extensive wildfires that typically occur at present.

We present the first population estimate for the little known and critically endangered Malherbe’s parakeet Cyanoramphus malherbi inhabiting Maud Island, New Zealand. From March 2007 to May 2009 we conducted surveys for the species at this site to document the status of this translocated population and to determine the relative value of Maud Island for the conservation of this species. Using a modified version of the mark-resighting method, we estimated that the Maud Island population of Malherbe’s parakeets has gone from an initial founder group of 11 captive-bred parakeets released on site, to a maximum of 97 during our survey period (assuming a 72% survival rate between trimesters). Out of a total of 221 sightings, 22% corresponded to un-marked individuals hatched on site. Our estimate of population size, coupled with the high reproductive potential of the species, suggests that translocation of captive-bred individuals to sanctuaries free of invasive predators is an effective management method for increasing the global population size of the species and eventually downgrade its IUCN threat category.

A project undertaken from 2003 to 2009 evaluated the efficacy of cattle exclosures to enhance breeding whinchat Saxicola rubetra numbers in a 65 ha study area comprising sub-alpine cattle-grazed pasture (42 ha) and hay meadows in the Southern Alps of Switzerland. Potentially suitable nesting sites were created in the pasture by erecting fences to exclude cattle, and this made available additional perches (providing hunting and song posts in territories) where previously mostly lacking. One 0.9 ha plot was excluded from grazing cattle with a wooden fence, and five smaller 0.1 ha plots with electric fences. Whinchats used the plots as parts of their territories and the fence posts as song posts and perches. The 0.9 ha plot secured whinchat territories until 2009. For the five 0.1 ha plots there was no clear effect on whinchat territory occupancy. Over the study period the whinchat population declined (following a general regional trend) from a high of 27 pairs in 1990 to a low of six pairs in 2009.

Mass trapping successfully achieved elimination of black rat Rattus rattus on Feno islet (1.6 ha), Terceira island (Azores archipelago), thus enabling roseate terns Sterna dougallii and common terns Sterna hirundo to recolonize the islet. Rats were first detected on Feno in 2003, when tern breeding-numbers had decreased dramatically. During 2005 no terns bred on the islet and in 2006 fewer than five common tern pairs attempted to nest. Rat eradication was initiated in September 2006. The last rats were captured in March 2007. Monitoring conducted in September 2007, and May and September 2008 indicated that rats had not recolonized. Common terns quickly resumed breeding on Feno islet but numbers (c.120 pairs in 2009) are still below peak levels (c.240-280 pairs) recorded before rat infestation. Roseate terns on the other hand were slower to return but recovered faster with around 260 pairs in 2009, representing 22% of the Azores population. The success of the black rat eradication shows that surveillance and timely action are fundamental to conserve tern colonies vulnerable to rat predation in the Azores.

On Coquet Island (5.4 ha), northeast England, a rapid increase in numbers of nesting herring Larus argentatus and lesser black-backed gulls L. fuscus raised concerns that the internationally important tern breeding colony would be displaced. The combined effect of several non-lethal control methods and systematic egg removal on these large gull species from 2000-2009, have been reductions in the number of gull pairs attempting to nest (from a peak of around 250 pairs to less than 20), the area occupied for nesting and nest density. The presence of the tern colony has been maintained, with increases in the population (5-year average) of roseate Sterna dougallii, arctic S. paradisaea and common terns S. hirundo.

There is extensive and compelling evidence that suggests changes in farmland bird abundance have been driven by changes in agricultural practice. Among these, the wide-scale change from spring to autumn cropping has consequences for the amount of food available to farmland birds over winter and associated survival rates. Oil-seed rape (OSR) Brassica napus is one crop that is primarily established in the autumn. While the leaves provide a valuable source of food for a few species, e.g. woodpigeon Columba palumbus, and may provide cover and micro-climates for invertebrate food for others, e.g. thrushes, there has been concern that autumn sowing of crops such as OSR removes the need to leave land fallow during the winter months. Fallow land in the form of over-winter crop stubble is a key foraging habitat for many birds, particularly granivorous species. It has been hypothesised that the recent wide-scale adoption of the broadcast method of establishment for OSR crops may have benefits for some species reliant on over-winter stubbles, as the crop is established into existing cereal stubble. However, our study indicates that bird densities are similar on broadcast OSR fields compared to non-inversion tillage OSR, and that densities in the broadcast OSR were lower than in many studies of bird use of over-winter cereal stubbles. This may perhaps be due to the rapid growth of OSR in the autumn, shading out the stubble and thus making it an unsuitable feeding habitat for many birds for much of the winter. As the available evidence suggests that cereal stubbles broadcast with OSR are unlikely to provide the benefits to farmland birds of traditional over-wintered stubbles, the decision on method of establishment for oilseed rape crops should be based on agronomic considerations.

From February 2004 to September 2007, a raptor feeding station was operational near the Laterza LIPU Reserve (Taranto Province, southern Italy). The feeding station measured 40 x 40 m and was enclosed by a 1.8 m high wire mesh fence to prevent large mammal access. An average of 50 sheep carcasses were supplied at the feeding station each year. Over 2,200 hours of observation at the feeding station were made, averaging about 550 hours per year. During observation periods, black kite Milvus migrans numbers recorded at the feeding station ranged from a minimum of five (in 2004) to a maximum of 53 (2006) annually; red kite Milvus milvus numbers ranged between one (2004) to 23 (in both 2006 and 2007). Only one Egyptian vulture Neophron percnopterus (in 2007) was observed at the feeding station. Provision of supplemental food at the feeding station may represent one factor explaining the establishment of a few breeding pairs of red kites and black kites, and increasing numbers of raptors recorded in the study area.

Avian brood parasitism lowers host fitness through several mechanisms, including the reduction of productivity of parasitized breeding attempts. Even when both host and parasite are native species, anthropogenic factors (e.g. habitat alteration) may increase local parasitism burden on rare hosts so as to require conservation action. To reduce brood parasitism rates by brown-headed cowbirds Molothrus ater (an increasingly abundant species within its North American range), most conservation action currently involves the removal of adult cowbirds in the hosts' breeding habitat. An alternative, but more labour intensive, management action is to remove cowbird eggs from host nests, but the benefits of such egg removal may be outweighed by the predatory behavior of cowbird females on host eggs if nests lack cowbird eggs. In this present study, parasitism of song sparrows Melospiza melodia near Ithaca, New York (USA) was used as a case study to evaluate the effect of removing cowbird eggs on productivity (i.e. young fledged per nest) of the host species. Although parasitized nests had naturally fewer host eggs than non-parasitized nests, there were no consistent differences in the numbers of host nestlings produced in non-parasitized, non-removal parasitized, and parasite-egg removal broods. Counter to the goal of removing parasite eggs, the proportion of host eggs producing nestlings was lower in egg-removal nests than in non-removal parasitized nests. It is therefore concluded that at this locality, conservation management to remove the eggs of brood parasitic brown-headed cowbirds is unlikely to increase song sparrow productivity.

Skylarks Alauda arvensis have declined by 53% across Britain since 1970, primarily in regions dominated by lowland farmland. To improve breeding opportunities in arable farmland, 'Skylark Plots' i.e. small (16-24 m2) unsown areas within winter cereal crops, were developed by the RSPB and tested in the Sustainable Arable Farming For an Improved Environment (SAFFIE) project. These plots increased the number of late summer breeding attempts and the number of chicks fledged per nest, compared to conventional crops. Skylark Plots are now included as a prescription in the Entry Level Stewardship (ELS) agri-environment scheme in England. The plots are usually created by turning off the seed drill during sowing. However, take up of this prescription has been very low; pernicious weed control and technical difficulties with sowing machinery have been cited as reasons for this. To broaden the appeal to farmers, the option to create the plots through herbicide spraying to remove the germinating crop, was introduced in 2008. Data on the optimum period for spraying and differences in vegetation architecture between undrilled and sprayed skylark plots was lacking however. As evidence from the SAFFIE project showed that plots with greater vegetation cover had higher invertebrate abundance and that skylarks use plots primarily when foraging for invertebrate chick food, the present study was conducted to compare the vegetation cover in undrilled plots with plots sprayed either in December, January or February (during crop germination).

The study showed that undrilled plots consistently had greater vegetation cover than sprayed plots, with the cover increasing in all plots from May to July (whilst remaining suitable for skylark use), the peak period of the skylark breeding season. Vegetation cover within sprayed plots was generally very low, particularly in February-sprayed plots. These differences in vegetation cover are likely to subsequently impact the abundance and accessibility of invertebrate prey available to skylarks during the breeding season with February-sprayed plots in particular being unsuitable for skylark foraging even in July. Our recommendation is that where possible, plots should be created at the time of sowing (turning off the seed drill) in autumn; if spraying is the favoured method of creation then this should take place no later than the end of December.

In a European context, Iceland has some of the highest levels of desertification (due primarily to historic overgazing, frequent volcanic eruptions and subsequent erosion) and also vast naturally occurring barren areas (mainly formed and maintained by  flooding of glacial rivers). Since 1988 efforts have been made, by the Icelandic Soil Conservation Service, to reduce sandstorms by revegetation on some sandplains in the region of South-Iceland. Action includes sowing strips of Nootka lupin Lupinis nootkathensis, and lyme grass Leymus arenarius and other grasses, with repeated fertilization. Very few bird species occur on Icelandic barren sands and if present, occur only at low densities. The effects of revegetation on avian abundance and diversity were evaluated by comparison to adjacent barren areas. Revegetation has a clear and a positive effect on some species which benefit from vegetated land. Meadow pipit Anthus pratensis and common snipe Gallinago gallinago occurred in high densities, particularly in mature strips of lupins, and other species of birds were colonising. These bird species are absent from barren sandplains.

Renovation of historic buildings and measures to limit access by feral pigeons Columba livia var. domestica has a strong negative impact on some lesser kestrel Falco naumanni populations by reducing nest site availability thus lowering reproductive success. In order to test the efficacy of nest boxes as a means to mitigate for such loss of nesting sites, we studied the occupancy rate of roof-top nest boxes and compared their performance to that of 'natural' nests (i.e. located in cavities in bulidings and under roofs within buildings). Of 200 nest boxes provided, 16 (8%) were used for breeding in the first year (2007) and 35 (17.5%) in the second year (2008); it is expected that occupancy will increase substantially in subsequent years. In 2007, the number of fledged young produced/pair in nest boxes (1.82 young) was similar to that of attic nests (1.66 young), whilst those nest located with cavities (2.70) had a much higher reproductive output. In 2008 the number of fledged young produced/pairs in nest boxes was 1.54.

A small but important population of the endangered Java sparrow Padda oryzivora nests within crevices between stone blocks of an ancient temple complex in Java. In response to nest site losses due to temple restoration, and subsequently further damage to nest sites caused by a major earthquake, artificial nest sites (wooden nest boxes, sections of bamboo, and coconut shells) were provided. In the subsequent breeding season (2007), two pairs of Java sparrows successfully nested in these wooden boxes, one pair fledging seven young and the second pair two young. In 2008, three pairs again nested in the wooden nest boxes (located in different trees): one nest had nine eggs but failed as the parents were taken by a local birdcatcher; the second nest had 12 eggs, six of which hatched and subsequently fledged; the third pair fledged three young. A coconut shell was prospected by one pair but not used for nesting.


Waterfowl and breeding bird surveys were conducted at Abberton Reservoir Special Protection Area between 2004 and 2006 as part of a study related to an environmental impact assessment. A secondary finding of these surveys revealed a significant level of mortality in spring for mute swans Cygnus olor, and other waterbirds that were colliding with nearby overhead power lines. In the spring of 2004, nine mute swans were killed through collision with the 132Kv power lines, while in spring 2006, 21 were killed. In the summer of 2006, over 500 red flight diverters (320 mm long, 175 mm diameter) were installed at 5 m intervals along a 1.5 km length of the power lines. In the spring of 2007 only one mute swan was killed through power line collision, while in spring 2008 none were killed. The perpendicular distances over which bird carcasses were found on the ground from under the overhead power cables ranged from 10-351 m. This should be taken into account when designing future collision mortality surveys for similar power lines. It is recommended that appropriate bird flight diverters are fitted as routine best practise when installing any new overhead power lines.

Since the mid 1970s the number of nesting roseate terns Sterna dougallii had declined on Coquet island. In 2000, tern nest boxes were installed on an artificial terrace on the island to provide shelter for tern eggs and chicks from their main nest predators, larger Larus gulls. Since 2003, all roseate terns breeding on Coquet Island have used nest boxes as nest sites and the number of breeding pairs has risen steadily.

A practical method of excluding non-native African giant land-snails Achatina spp. from trees containing bird nesting cavities was developed on Mauritius following previous snail incursions in two successive breeding seasons that proved fatal to echo parakeet Psittacula eques chicks. The use of a copper strip attached below nest cavities in susceptible trees has to date proved a successful technique.

Nest boxes have been provided for echo parakeets Psittacula eques in order to overcome a shortage of natural tree cavities and to facilitate intensive conservation management of this critically endangered species. Despite initial refusal to use nest boxes, a high percentage of successful nesting attempts now occur in them. In the 2006/07 breeding season, 73% of nests in which eggs were laid were in nest boxes (n = 56); 71% of attempts in nest boxes that season were successful (i.e. chicks fledged).

After the provisioning of artificial nest-sites (nest boxes, clay pots, 'breeding walls', 'breeding towers' and nest-cavities) for lesser kestrel Falco naumanni in the Castro Verde Special Protection Area in southern Portugal, artificial nests of all types were rapidly colonized and the occupation rate exhibited a positive trend over time. The spectacular growth of the Portuguese lesser kestrel population can be explained by the increase in numbers in Castro Verde, suggesting that providing nest sites is an effective measure in the conservation of this threatened species in Portugal in localities where suitable foraging habitat is present.


On a newly acquired improved grassland, chisel ploughing was used on a two year rotation to break up the surface of the sward to create small hummocks and divots amongst which it was hoped lapwings Vanellus vanellus would nest. The water level was also increased and a seasonal sheep and cattle grazing regime introduced. Between 2000 and 2005, lapwings increased from 10 to 81 pairs and redshank Tringa totanus increased from 11 to 29 pairs.

An area of improved grassland was dominated by rushes Juncus spp. and purple moor-grass Molinia caerulea. In order to try and attract breeding common snipe Gallinago gallinago, the rush was cut in 2003 with tractor mounted mowers and then grazed. In addition, 18 small scrapes were dug and higher water levels were maintained. The number of snipe increased from one nesting pair in 2003 to 11 nesting pairs in both 2004 and 2005.

Patches of rushes Juncus spp. were cut in mid-winter with the objective of creating open nesting areas the following spring for wading bird on islands in Lower Lough Erne. Lapwing Vanellus vanellus nested almost exclusively in the cut areas. Redshank Tringa totanus nested in uncut areas, but their chicks benefit from the presence of the adjacent short, open areas for feeding. The breeding populations of both species increased considerably in response to this management intervention.

A range of approaches were adopted to deter large gulls Larus spp. from competing with nesting terns Sterna spp. A gas gun, scarecrows, rockets, taped distress calls and direct human disturbance were all effective. A 'humming line', a grid of binder twine and 'scarer' rope all had associated practical problems. A number of methods are deployed over the breeding season in order to prevent the gulls from habituating to any one technique.

A series of gravel islands were once important for breeding terns and small gulls, but their numbers declined with none breeding in 2002. The possible causes included vegetation succession and competition and predation from large gulls. In February 2005, invading scrub was removed and the islands re-profiled and lowered to encourage winter flooding in an attempt to improve breeding habitat. Single pairs of common tern Sterna hirundo nested in 2005 and 2006 and five pairs of black-headed gull Larus ridibundus in 2005. However, high numbers of herring gulls Larus argentatus also bred in both years.

A 15 ha saline lagoon was created in 2002 as part of a flood defence scheme at a site on the east coast of England. It has subsequently been used by a range of wintering and breeding waders and waterfowl.

The sea wall at Freiston Shore, eastern England, was breached in three places in 2002 to create 66 ha of intertidal habitat. By September 2005, 70% of the site was covered by salt marsh plants. The area now supports large numbers of wintering geese, duck and waders, as well as smaller numbers of passerines. It has proved popular with people with 57,000 visitors in 2005.

Manx shearwater Puffinus puffinus and Atlantic puffin Fratercula arctica ceased breeding on Lundy Island due to nest predation by introduced rats Rattus spp. Following successful rat removal, both seabird species have successfully resumed breeding on the island.

To help resolve the conflict between pygmy cormorants Phalacrocorax pygmeus and fish farmers, the birds were scared away from Bet She'an Valley before the breeding season started. The cormorants have subsequently relocated to other, safer breeding sites.

At a coastal site in Wales, year-round cattle grazing was introduced to an area of ungrazed semi-improved grassland,which was rarely used by foraging choughs Pyrrhocorax pyrrhocorax. Grazing greatly reduced the sward height and the area became a major feeding area for chough.

At Leighton Moss RSPB Reserve, northwest England, bearded tit Panurus biarmicus nest boxes were designed and installed. Over 42% of the nest boxes have been occupied over the eight years of their use. Nest boxes placed over water are more likely to be used.

At Berney Marshes RSPB Reserve, water levels were raised, foot drains were added, and grazing by sheep was introduced. The plant communities shifted towards communities' characteristic of lowland wet grassland. Breeding wading bird numbers increased in response to these habitat changes.

The effects of introducing cattle grazing to a saltmarsh on breeding redshank Tringa totanus were investigated. The density of breeding redshank did not noticeable change after introduction of grazing.

Suitable breeding areas for ground nesting waders were restored by mechanically scraping off vegetation that had colonized limestone slag banks. In response, breeding numbers of ringed plover Charadrius hiaticula, oystercatcher Haematopus ostralegus and lapwing Vanellus vanellus doubled in the year following restoration. Early successional plants also benefited.


The effects of adding organic matter (barley straw) on aquatic invertebrate food supply for waterbirds in an artificial saline lagoon in eastern England was investigated. The addition of barley straw resulted in an increase in benthic invertebrate biomass the following year, but was not considered a successful long-term management strategy to boost invertebrate populations.


Off the coast of New Zealand, small quantities of shark liver oil dripped onto the water surface behind a fishing boat deterred pelagic seabirds from taking bait on long-line hooks.


An area dominated by purple moor grass Molinia caerulea was burnt, flail mowed, heather seed was added, and then grazed. Heather Calluna vulgaris seedlings were observed the next summer and grazing kept Molinia growth in check.


Restoration and creation of footdrains on grazing marshes in eastern England improved breeding habitat quality for lapwing Vanellus vanellus and redshank Tringa totanus, two wader species declining in numbers throughout lowland England. In particular, they provided increased foraging habitat for these wader chicks which prefer to forage around the invertebrate-rich margins of the footdrains. Numbers of breeding lapwing and redshank have increased dramatically, and wintering waders, ducks and geese have also benefited.