Garden Birds - Mike Toms Collins New Naturalist Library

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pastime here in the UK and a great many of us put out mixed seed, sunflower hearts and fat- or suet-based products for our garden birds. The addition of such food to the environment represents a substantial supplementation of the resources available to wild birds, yet we still lack a clear understanding of its effects. In a wider research context, we know that food supplementation can increase survival rates (Brittingham & Temple, 1988a), change community and population structure (Galbraith et al., 2017b), alter behaviour (Saggese et al., 2011; Plummer et al., 2015) and impact on wider biodiversity (Orros et al., 2015a). It has also been linked to disease transmission in birds (Lawson et al., 2018) and to health and well-being benefits in people.

      Through this chapter we will explore how and why supplementary food is provided to garden birds, how provision varies across countries, cities and cultures, and the consequences that such provision has for the birds that visit our gardens to partake of this significant resource. Understanding why people feed wild birds and the extent to which they appreciate its costs and benefits will be central to our exploration, as will a review of the scale of food provisioning, which is where we will start this chapter.

      THE PROVISION OF FOOD FOR WILD BIRDS

      It has been estimated that between one-quarter and two-thirds of households across major parts of Europe, North America, Australia and New Zealand provide food for wild birds (Thomas, 2000; Ishigame & Baxter, 2007; United States Fish & Wildlife Service, 2011; Davies et al., 2012). Within the UK, and using figures from the English Housing Survey and other studies, Davies et al. (2009) reported that 48 per cent of households, and 51 per cent of households with a garden, participated in feeding wild birds. Perhaps more interestingly, the study also reported that 28 per cent of households, and 23 per cent of households with a garden, specifically used bird feeders. An earlier and often quoted study by Cowie & Hinsley (1988a) put the figure at 75 per cent, but was based on a small sample of households (in Cardiff) and did not properly account for those questionnaires that were not returned. Work in Reading, Berkshire, using a face-to-face questionnaire approach outside supermarkets, came up with a figure of 55.3 per cent for the proportion feeding wild birds, of which 65 per cent reported that they fed all year round (Orros & Fellowes, 2015b). Marketing work by the RSPB, using two separate telephone surveys of randomly selected groups of 1,000 people and carried out in summer and winter 2004, indicated that 56 to 61 per cent per cent of people over the age of 16 had fed their garden birds during the past year (RSPB, unpublished).

      FIG 12. Suet-based foods, such as fat balls, have become very popular with UK householders, their use targeted at small garden birds like tits and Starlings. (John Harding)

      A rough calculation by Zoe Davies and colleagues, based on the population sizes of birds known to use seed feeders, suggests that there is at least one bird feeder for every nine potentially feeder-using birds. This does not allow for the fact that many households provide food in more than one feeder, or that many bird feeders are sitting empty at any one point in time. RSPB data, again from their marketing survey, suggest that on a typical summer’s day one in every seven gardens has at least one empty bird feeder. Even so, it does underline the potential scale of food provisioning taking place within the UK – something Davies et al. (2009) have suggested could equate to a standing crop of 2,580 tonnes of bird food. Figures from the Pet Food Manufacturers Association put UK bird food sales at c. 150,000 tonnes annually, representative of an annual consumer spend in excess of £200 million. O’Leary & Jones (2006) suggest that in excess of 500,000 tonnes of food is provided annually across the UK and US combined, while United Nation’s figures from 2005 put the global bird food industry’s value at $5–6 billion, with growth of c. 4 per cent annually since the 1980s (Lin, 2005).

      Thanks to the periodic National Survey of Fishing, Hunting, and Wildlife-Associated Recreation, we know that expenditure on wild bird foods within the United States has doubled over a 20-year period, exceeding $4 billion per year by 2011 (United States Fish & Wildlife Service, 1991; 2011). We lack a comparable survey within the UK, and securing commercially sensitive sales information from the wild bird care sector is problematic, but it is thought that the current annual UK spend on wild bird care products (food, feeders and nest boxes) is between £220 million and £500 million (Fuller et al., 2012).

      FIG 13. The proportion of BTO Garden BirdWatch participants presenting different foodstuffs at their garden feeding stations each week across four of the project years (2014–17). Note the increase in fat and suet provision during the winter months. ‘Live’ foods include dried mealworms. Data reproduced with permission from BTO.

      Information from the weekly submissions made by BTO Garden BirdWatchers provides a measure of the change seen in different types of bird food (see Figure 13) but these data come from a subset of the national population (see Chapter 6) and do not reveal the actual quantities provided. Having said this, as part of BTO’s work on microevolution in Blackcaps (see later in this chapter), we were able to estimate that the total volume of sunflower hearts and fat products provided by BTO Garden BirdWatchers during the winter months more than doubled from 6.35 tonnes to 17.26 tonnes over the course of a 12-year period (Plummer et al., 2015).

      WHY DO PEOPLE FEED WILD BIRDS?

      While bird feeding is clearly influenced by external factors, such as socioeconomic status and having access to a garden, it is also shaped by intrinsic and motivational factors. At its heart, bird feeding may be seen as a humane act, an act of kindness reflecting a wish to help a fellow creature. However, this act may be further shaped by other motivations, such as guilt or a wish to learn. Despite the obvious commercial advantages to be gained by understanding motivations for feeding wild birds, there has been relatively little work in this area and many of our assumptions about why people provide supplementary food for wild birds remain untested (Jones & Reynolds, 2008). Understanding motivations requires a considered and rigorously scientific approach; it is all too easy to inadvertently bias a response from a study subject by asking a question in the wrong way.

      The work that has been done suggests that people feed wild birds for a range of different reasons driven by underlying environmental, cultural and philosophical perceptions (Davies et al., 2012). Many people derive pleasure from feeding wild birds and in many instances the provision of food is simply a reflection of this. Others feed because they are concerned about wild birds (and other creatures) and wish to nurture and support them. Some provide food because of the experiential knowledge that is gained, while others seek to counter the guilt that they feel over wider human impacts on the environment.

      Examination of a random sample of 1,000 participants in BTO’s weekly Garden BirdWatch scheme (Schreiber, 2010) found that ‘pleasure’, ‘contributing to the survival of wild birds’ and ‘studying behaviour’ were the top three justifications given by respondents for feeding. ‘Responding to environmental degradation’ and ‘teaching children’ were also given as reasons for feeding. Of course, participants in a citizen science scheme like Garden BirdWatch are unlikely to be representative of the wider UK public; they have sufficient interest in garden birds to have become involved in a rigorous monitoring scheme and will have been exposed to articles delivering information and messages on the practices associated with feeding wild birds. At this point it is just worth noting that the provision of supplementary food is sometimes practised for other reasons; conservation practitioners use supplementary food to enhance the survival and reproductive success of endangered species, while others use it to reduce predation pressure by provisioning predators; some use it to bring animals to sites where they can be observed or even hunted.

      FIG 14. Peanuts were one of the first foods provided specifically for wild birds visiting UK gardens. Originally presented loose or in net bags, peanuts are now typically provided in mesh feeders, though their use has fallen with the arrival of new high-energy seeds. (Jill Pakenham)

      The

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