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Birds represent the most diverse group of terrestrial vertebrates on the planet: the 2013 Red List of the International Union for Conservation of Nature (IUCN) identifies 10 065 described species (IUCN, 2013). Birds have established themselves on every continent and in almost every available habitat. Their evolutionary success lies in their incredible versatility. Although admired for their ability to fly, birds have mastered almost every other form of locomotion. They range in size from the 2 g Bee hummingbird Mellisuga helenae to the 135 kg Red-necked ostrich Struthio camelus camelus. This degree of diversity served as the basis for one of the most revolutionary scientific theories: Darwin's Theory of Evolution by Natural Selection (Darwin, 1859). Through this process, albeit not ‘natural’, humans over the course of thousands of years domesticated the Red junglefowl Gallus gallus into today's chicken, a bird that has had an incredible impact on human civilization. At the time of writing, chicken is the most-consumed source of animal protein in the United States, accounting for an annual consumption of c. 36·3 kg per capita (Adler & Lawler, 2012). Animals (including birds) not only provide a direct food source but also are responsible for pollinating approximately half of all plant species, including human food-producing crops (FAO, 2013).

In addition to playing a role in feeding the world's seven billion people, birds also provide numerous other economic benefits. In South Africa alone, the annual expenditure on avitourism runs into millions of dollars (DTI, 2010). The Phillip Island Nature Park penguin parade in Victoria, Australia, is the country's third largest tourist destination and attracts more than half a million visitors, who have an economic impact (both direct and indirect) of around AUS$66 million (c. US$58 million) (Marsden Jacob Associates, 2008). In the USA, the bird-watching industry is estimated to contribute around US$85 billion in overall economic output (Pullis La Rouche, 2006).

Birds also provide innumerable ecosystem services and as a result serve an important function as indicators of the state of the environment. Playing the role of the ‘canary in the coal mine’, they have alerted us to changes in their habitats. Chronicled in Rachel Carson's Silent Spring (Carson, 1962), dramatic drops in the numbers of Peregrine falcons Falco peregrinus and other raptors in the USA and Europe in the 1950s and 1960s drew attention to the use of the pesticide dichlorodiphenyltrichloroethane (DDT). A more recent example of environmental contamination is the use of diclofenac, a common anti-inflammatory drug administered to livestock, and the effect it has had on Asian vulture populations. In the 1990s vulture populations of three species, White-rumped vulture Gyps bengalensis, Indian vulture Gyps indicus and the Slender-billed vulture Gyps tenuirostris, in India dropped by over 90%. In 2003, Dr Lindsay Oaks discovered that diclofenac was fatal to vultures if they ate from a carcass of an animal that had been treated with the drug during its lifetime (Oaks et al., 2004). In the cases of the use of both DDT and diclofenac, the sudden unsettling of the balance of the respective ecosystems had additional environmental, economic and cultural consequences. These well-documented cases resulted in significant policy change that culminated in the elimination or dramatic reduction of the use of DDT in 1972 and diclofenac in 2006.

There is growing evidence that climate change will become one of the major threats to species in the 21st century (Foden et al., 2008). At the time of writing, birds are one of the primary indicators for the consequences of climate change. The 2008 IUCN Red List identified some 35% of assessed bird species as being ‘climate-change susceptible’ (Foden et al., 2008). The varied and often unexpected effects of global warming on a variety of species have been validated by numerous studies of birds (Wells, 2007). Certain species of North American birds are nesting and migrating earlier (Torti & Dunn, 2005). Short-distance migrants, such as the Yellow-rumped warbler Dendroica coronata and Ruby-crowned kinglet Regulus calendula, have shown an advance in migratory arrival dates of almost 2 weeks since the 1900s (Wells, 2007). Climate change has also resulted in the spread of mosquito-borne avian pathogens, such as West Nile virus (WNV), and avian conservation efforts will continue to be challenged with controlling WNV spread and transmission (Nemeth & Oesterle, 2014). Zoological institutions can play a significant role in the monitoring of mosquito distribution and behaviour. For example, Quintavalle Pastorino et al. (in press) describe the World Association of Zoos and Aquariums (WAZA) Mosquito Surveillance Initiative Project (MOSI) and the results of its pilot study, which confirm the feasibility of conducting standardized year-round mosquito monitoring in zoological institutions and the kind of unexpected findings that can be derived from global networking.

Despite the well-studied and documented cultural, economic and ecosystem benefits that birds provide, they nevertheless face a precarious future. The IUCN Red List suggests a steady and continuing deterioration in the status of the world's birds between 1988 and 2008. In these 20 years, 225 birds have become more threatened compared with just 32 species that have become less threatened (IUCN, 2008). At the time of writing, some 198 species of birds are classified as Critically Endangered (IUCN, 2013). Particularly alarming are sharp declines in many formerly common and widespread species. In North America, for example, the Northern bobwhite Colinus virginianus population has declined by around 82% in the last 40 years. Consequently Northern bobwhite has been redefined from Least Concern to Near Threatened on the IUCN Red List (BirdLife International, 2008). In light of these trends, avicultural institutions must be prepared to make detailed assessments prior to attempting to establish ex situ populations for conservation-breeding programmes (Collar & Butchart, 2014).

Zoo professionals have a clear understanding and appreciation of the importance of maintaining biodiversity. With more than 300 zoo members and 700 million visitors each year, WAZA members have an incredible potential to change the course of the over 1300 birds currently listed as threatened on the IUCN Red List (IUCN, 2013). Conservation breeding and subsequent reintroduction projects have prevented the extinction of six bird species in the past 20 years (Butchart et al., 2006). For two decades Taronga Zoo, Australia, has been involved in the recovery of the Critically Endangered (IUCN, 2013) Regent honeyeater Anthochaera phrygia, playing a key role in this effort from preparatory work on analogue species, including breeding techniques, transport and release protocols, community awareness, through to the release of captive-bred birds (Liu et al., 2014). Similarly, since 1993 Xcaret in Mexico has been working to reintroduce the Scarlet macaw Ara macao cyanoptera to parts of its former range. This endeavour has culminated in the release of 36 Scarlet macaws in 2013 (Raigoza Figueras, 2014). Another example of collaborative conservation effort is provided by CRAX Brazil, a non-profit non-governmental organization that has been working with partners to prevent the extinction of the Alagoas curassow Pauxi mitu. Extinct in the Wild since 1979, reintroductions are potentially scheduled within 3 years (de Avelar Azeredo & Simpson, 2014).

Unfortunately, few zoo populations of threatened species, or any species for that matter, are managed in a sustainable manner that would categorize them as altogether successful conservation-breeding programmes. Most populations, including birds, are disadvantaged by small population size resulting from limited space, poor growth rates as a result of poor survival and/or reproduction, ineffective population management, and low genetic diversity. These challenges can seem overwhelming, making it difficult to recognize success, and the positive impact that biologists, educators and collection managers have on the preservation of any given species. Within this volume descriptions of innovative tools that can be utilized to minimize some of the suggested challenges are presented. Lynch & Snyder (2014) outline, on behalf of the Association of Zoos and Aquariums (AZA), the Blue-grey tanager Thraupis episcopus Species Survival Plan (SSP), a management strategy to address the many sustainability challenges facing passerines. The European Association of Zoos and Aquaria (EAZA) Flamingo Taxon Advisory Group (FTAG) has similarly provided a management survey and 11 strategies to enhance reproduction of flamingos in captivity (King & Bračko, 2014). Bračko & King (2014) introduce the Aviary Database Project as a potential new collaborative approach to designing aviaries as a means of improving breeding, visitor experience and welfare.

There is enormous potential to make positive changes in these captive-management challenges. In April 2013, the AZA Avian Scientific Advisory Group (ASAG) hosted an inter-regional zoo-association workshop addressing this very issue of sustainable ex situ avian populations. All regions agree that management changes are required. The WAZA Committee for Population Management suggested Global Species Management Plans (GSMPs) as a possible solution (WAZA, 2013). The benefits of such programmes are given below.

  • Demographic and/or genetic supplementation.
  • Collaborative research efforts.
  • Capacity building in husbandry, population management and other expertise.
  • Information sharing.
  • Public awareness and education programmes.
  • Support of in situ conservation activities.

Of course even GSMPs have their own set of challenges including animal-health risks, and financial, logistical, legal and political obstacles. However, conservation breeding is just one of the unique tools at our disposal.

Zoological institutions have the opportunity to conduct extensive research into the behaviour, physiology or sensory systems of a species. The National Zoological Gardens of South Africa has, through captive studies, ascertained the complex breeding biology of the Red-billed oxpecker Buphagus erythrorhynchus (Plantan et al., 2014). The Lowry Park Zoo, FL, USA, has documented similar breeding parameters for the Vulnerable Shoebill Balaeniceps rex (Tomita et al., 2014). Conservation tools, such as artificial incubation parameters/techniques, have also been extensively studied in zoological settings. Cornejo et al. (2014) share the novel methods utilized by the Bronx Zoo/Wildlife Conservation Society, NY, USA, to artificially incubate eggs of the Endangered Maleo Macrocephalon maleo successfully. These types of ex situ studies would be difficult if not impossible to conduct with free-ranging animals and the information gained can have a direct conservation benefit for the species in question (Association of Zoos and Aquariums, 2013).

Zoological institutions have an ethical responsibility to ensure the well-being of the animals in their care and the scientific responsibility to gain a greater understanding of the well-being of those animals by advancing animal-welfare science (Association of Zoos and Aquariums, 2014a). In-depth research into the links between provision (enclosure, husbandry), behavioural performance (reflecting internal motivation) and perceived welfare state (from behavioural cues) can inform management for good welfare over many decades of a bird's life (Rose et al., 2014). In a strategic move to enhance animal welfare, the Odense Zoo, Denmark, no longer pinions birds and built a large aviary for bird taxa that are often pinioned (Klausen, 2014). Wesley & Brader (2014) describe a detailed behavioural-budgeting study of the Brown kiwi Apteryx mantelli leading to a better understanding of enclosure use and intra-specific interaction. Although zoos hold high standards for the husbandry parameters mentioned above, nutritional composition of diets offered to animals in zoological institutions often remains unknown. Fidgett & Gardner (2014) highlight advances in nutrition, useful resources, means of keeping feeding records, and tools available to evaluate and review avian diets in nutritional terms.

Zoos are also investing more funds and in-kind services than ever in in situ initiatives that help to secure the long-term survival of species in natural ecosystems and habitats. In the AZA alone, 184 of the 241 accredited institutions spent US$160 million on over 2670 conservation initiatives in more than 100 countries (Association of Zoos and Aquariums, 2014b). Whether securing key breeding colonies of Vulnerable Humboldt penguins Spheniscus humboldti (IUCN, 2013) in Punta San Juan, Peru, providing financial and technical support for the in-country conservation breeding and release of threatened Indonesian passerines (Owen et al., 2014), or providing husbandry and veterinary expertise for threatened Gyps vultures in Asia, there is a great capacity to make positive changes in the status of avian species.

The potential role of zoological institutions in the intensifying nature of wildlife conservation is unique (Conway, 2011). The papers presented here by our distinguished zoo colleagues and partners exemplify the contributions we can all make towards conquering avian challenges associated with captive breeding, health, nutrition, population management, reintroduction and conservation. We hope these achievements will inspire you to contribute towards the conservation of bird species in peril, and to recognize the challenges being faced in the opportunities for growth and a better understanding of our natural world. As T. S. Eliot said ‘If you aren't in over your head, how do you know how tall you are?’

References

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  2. References
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