The land sharing and “wildlife friendly farming” approaches stress the importance of incorporating biologically diversity into farming practices as a way to reduce the reliance on agrochemicals, and to increase the value of the agricultural matrix for wildlife habitat within the agroecosystems . The main critique of the land sharing approach assumes lower yields from non-intensive agriculture coupled with the need for more agricultural land conversion . More recently a combined approach of land sharing/sparing was proposed to disentangle the debate and co-op favorable practices from both strategies . The importance of the surrounding natural ecosystem is equally important in both land sparing and land sharing strategies for biodiversity conservation purposes. Natural ecosystems provide irreplaceable habitat for wildlife, in particular for highly specialized forest-dependent specialist, migratory species, and local endemics . Core, well-preserved, extensive areas as well as fragments play a role in the landscape connectivity and meta-population dynamics . One proposed strategy to augment the quality of the agricultural matrix is to increase landscape complexity through conservation of native vegetation fragments within simplified agroecosystems . These remnants of vegetation and restored some of the benefit of these vineyards as wildlife habitat that allow increased levels of biodiversity compared to agricultural fields without structural diversification . Forest patches and fragments can contribute to higher species richness within the agricultural matrix and increase ecosystem services provide by biodiversity . Non-cropped areas increase the landscape heterogeneity in time and space, increasing sources of food, shelter, roosting, and nest sites which are important to support wildlife in agroecosystems .
Most current literature on conservation in agroecosystems comes from tropical systems, 30 plant pot whose climatic regimes and seasonality differ greatly from temperate ecosystems. These results provide new evidence of strategies for harmonizing food production with biodiversity conservation. extending these data to advance knowledge of the impact of agroecosystems on wildlife in mediterranean type ecosystems with not only provides regional insights but adds to the global land sparing- land sharing debate. In mediterranean type ecosystems, vineyards are a dominant land cover type and important for the economy of these regions . The remaining natural areas in these regions correspond to some of the most unique and threatened ecosystems worldwide in terms of number of local endemic species that are at risk from continued land use change . The immediate and future impacts of vineyards on wildlife are poorly understood and research in these agroecosystems can help long-term protection of these biodiversity hotspots. Birds are one of the most visible vertebrates in agroecosystems and can be used as indicators of habitat quality or levels of disturbance . Birds provide significant ecosystem services such as pest control within agroecosystems , although some species could be considered agricultural pests when they decrease yields . In these studies, I aimed to determine the influence of vineyards on bird communities in Mediterranean type ecosystems located in Chile and California, respectively. I utilized a natural experimental framework comprising a gradient of increasing vineyard land cover in both study areas. In Chapter one, I review the current literature to evaluate and summarize the impact of agroecological practices on bird conservation. Several practices, including increasing the structural complexity of habitat, organic management, and the supply of artificial habitats such as the addition of bird nest boxes, have been demonstrated to promote bird conservation.
In Chapter two, I examine the how vineyard and several site variables explain bird species detection rates and explore species co-occurrence patterns corrected by vineyard and shrub influence. Results showed that vineyards promote a subset of species, referred to as agricultural adapter birds that interact with non-agricultural adapter birds and thereby can change community composition. In Chapter three, I evaluate the influence of within-vineyard fragments of native vegetation and surrounding native vegetation on bird communities of central Chile. Results showed a positive influence on not only surrounding native ecosystems, but also remnant fragments within vineyards, on bird functional groups, including local endemics birds. In Chapter four, the influence of vineyard at the landscape scale in compared across both study regions by evaluating the influence of vineyards on species and co-occurrence patterns when corrected by vineyards. Results were similar in both study regions, with increasing vineyard proportion favoring agricultural adapters and increasing negative interactions between agricultural adapters and the rest of the bird community. Indirect effects in ecology are difficult to assess but potential consequences for ecosystems could affect resilience and inter specific interactions leading to trophic cascades . Similar findings in both California and Chile suggest indirect impacts from agriculturally adapted species on surrounding natural ecosystems may be important globally. Summarizing detailed information on birds and agriculture highlight the practical strategies that can be implemented across the vineyard landscape for the benefit of biodiversity conservation. The importance of not only the surrounding natural landscape but also fragments within vineyards highlights farm-scale management that can be implemented by growers seeking to conserve birds will have an impact on bird conservation. This result can inform practical environmental policy and management and promoted to growers or non-governmental organizations to facilitate restoration strategies within vineyards.
The landscape and farm-scale nature of these results are applicable not only for conservationists but also for growers implementing sustainable environmental programs, and may be part of a win-win strategy for conservation and sustainable wine production. Approximately ten thousands bird species are distributed across terrestrial and marine ecosystems . A significant number of these species cannot adequately survive in anthropogenic ecosystems . Today, about 13% of bird species worldwide are threatened , including more than 25% of omnivorous and frugivorous birds, and approximately 30% of herbivorous, scavenger, and piscivorous birds . Expected changes in climate could affect the distribution of birds species and their ecosystem functionality and ability to adapt to anthropogenic environments . Conservation beyond protected areas is needed to prevent mass extinctions , and improvement of suitability of agroecosystems for birds, will play an important role in conservation. Birds are one of the most visible vertebrates in agroecosystems. Many bird species have adapted to new anthropogenic environments through thousands of years of co-existence with humans, and although some can become pests of crops, multiple species provide multiple ecosystem services through their roles as scavengers and pollinators and through contributions to pest control, seed dispersal, nutrient cycling, etc. . However, land use change to agriculture and agricultural intensification have been reported as major threats to biodiversity conservation globally, as these activities have increased the extent of which natural habitat have become homogenized and simplified . Agricultural intensification have been documented to drive significant change in bird phylogenetic diversity . Loss of bird species is occurring at fast rates and therefore severely impacting ecosystem service provisioning in agricultural landscapes . These trends can be somewhat reversed by adopting agroecological practices and designs that create favorable habitats for birds in agricultural systems while maintaining acceptable crop yields . I review how agriculture drives land use change and its impacts on birds,grow raspberries in a pot and identify key threats to birds in agricultural systems. From an agroecological perspective I review field studies and meta-analyses to detail the role of the birds in agroecosystems, the associations of birds with specific crops, and the impacts of agricultural management on birds, including both generalizable trends and case studies from temperate and tropical agro-environments. I also explore opportunities to conserve birds through more biodiversity friendly farming systems and practices and how certain agroecological management strategies can enhance the beneficial roles birds play in agroecosystems. Literature was identified using search engines , first with general topics then with refined phrases . Different possible combinations of these key words were used in order to perform an extensive search on each specific topic. I compiled 205 documents used to conduct the review, consisting of 198 journal articles, four online resources, and three books. Studied used where selected and characterized based on a) experimental/influence design, meta-analysis; b) region , temperate areas , tropical areas , and tropical and temperate areas, and publication date .The studies used are publicly available and represent a non-random representation of this area of research. The data may be geographically biased by three main factors: firstly, temperate European countries and the USA have a longer history of research in agroecosystem biodiversity, likely resulting in more studies in this field; secondly, tropical countries have more research conducted in agroforestry systems , especially from long term studies in Central America; thirdly, developing countries from the Global South were not well represented in this study due to gaps in information.
However, this review compiles the most recent advances in this field, highlighting their significance for agroecological approaches for conservation. Biological control of insects by birds in agroecosystems is considered to be one of the main ecosystem services provided. It is estimated that reduction of 20-70% of the arthropod biomass in crop fields can result from consumption by birds, although this depends on season and arthropod population size . This ecosystem service provided by birds was recognized by the US Department of Agriculture in 1885, when the division of economic ornithology was created, but phased out in the second half of the 20th century when the use of chemical pesticides became prevalent . Recent research has revitalized interest in biological control provided by birds in agroecosystems. In Mexico, an exclusion experiment in shaded coffee reported that birds and bats significantly reduced insect pest populations, particularly during the wet season, suggesting that both birds and bats play a role in the provision of ecosystem services . In Jamaica, an exclusion experiment in coffee demonstrated that bird predation on the coffee berry borer reduced production costs by US $310/ha, equivalent to ~12% of the crop value. In the case of California alfalfa fields, an exclusion experiment reported that bird biological control of pests reduced insect abundance by 33% . The introduction of the threatened New Zealand Falcon in vineyards reduced grapes eaten by introduced song birds by 95% and by native birds by 55%, providing an ecosystem service that could reduce pest management costs by US $234-$326 per hectare . Western burrowing owls consumed more prey in irrigated fields in comparison with the semi natural shrub–steppe of sagebrush and perennial bush grasses in Idaho with no differences of prey abundance between the sites . Woodpeckers can act as biological control agents of insect larvae in apple orchards. For example a study in Nova Scotia between 52-90% of the insect predation was attributed to woodpeckers over seven years across 47 orchards . In Chinese flooded rice fields Huang et al. reported that field leaf hopper abundance was reduced by 63-77% and weed biomass by 50-94% in rice-duck systems, increasing the yield by 295 kg/ha while reducing the cost in agrochemicals. Further, the rice-duck system reported better quality rice of grains . In a cereal crop, biological control by birds was higher in an organic field within a diverse landscape than in conventional simplified monocultures . Interestingly, Maas et al. reported that birds and bats provide similar effects on biological control in the tropics as compared with temperate and boreal ecosystems. These noteworthy results provide novel quantitative insight into the role of birds in agroecosystems and their economic benefits. Birds form part of this interactions include intra-guild predation , functional redundancy , and facilitation or niche partitioning . In agroecosystems where few organisms are top down predators, like birds, the presence of these predator organisms could drive shifts in communities . Consequently, the effect of birds as biological control in agroecosystems could be considered essential for sustainable agriculture, and be based on direct predation decreasing abundance of arthropods or/and other vertebrates, or indirect by affecting the behavior of the prey . Additionally, one of the most profitable activities related to birds, with potential to be implemented in agroecosystems, is bird watching. Bird watching is a popular activity in some countries with great potential to help meet conservation goals . Biggs et al. found that empowering local communities in South Africa as guides for bird tourism permitted significantly increases in their monthly earnings by ~$US 250. Further such activities also increased the guides sense self-worth and self-determination, and instilled a sense of pride in their local environment, with in turn led to direct conservation benefits. Another economic argument tied to birds in agriculture is that many consumers are willing to pay more for produce derived from wildlife friendly farming systems.