Food For Wild Birds Research Articles

Supplementary feeding of birds during the winter influences measures of avian community structure in yards in a subtropical city.

Supplementary feeding, the intentional provision of food to wild birds is a common activity in developed nations during the winter. The energy inputs represented by supplementary feeding are vast, and thus it is likely an important mechanism shaping bird communities in urban areas. However, research in this regard has mainly occurred in temperate and non-urban settings. Moreover, few studies have been informed by supplementary feeding habits of local community members limiting their inference. We evaluated the effects of two commonly provided wild bird foods on the abundance and species diversity of birds in yards over two winters in San Antonio, Texas, United States, a city located in a subtropical region. We used a reversed Before-After-Control-Impact experimental design in which yards were randomly allocated either mixed seed, Nyjer, or no food (control) between November 2019 and March 2020 (Year One). Between November 2020 and March 2021 (Year Two) supplementary food was not provided in any yards. Point counts conducted during both years of the study revealed that overall bird abundance was consistent between years in control yards and yards provided with Nyjer. In contrast, overall bird abundance was statistically significantly higher when supplementary food was present in mixed seed yards, driven by an increase in granivorous and omnivorous species. In contrast, supplementary feeding had no statistically significant effect on the abundance of insectivorous species or on species diversity, although species diversity tended to be higher in the presence of mixed seed. Our study demonstrates that wild bird food commonly provided by community members influences measures of avian community structure during the winter in urban yards in a subtropical city. However, these results depend on the type of bird food provided. Our results provide insight into the processes underlying the effects of urbanization on bird communities, and thus have implications for the management of urban birds more broadly.

Molecular diet analysis of common cranes (Grus grus) under supplementary feeding based on fecal DNA metabarcoding

AbstractThe migratory and omnivorous common crane (Grus grus) uses a nature reserve with crucial ecological value that provides supplementary food resources, although the extent of their use by these cranes is unknown. In this study, we used DNA metabarcoding of plants through the chloroplast rbcL gene to investigate the diets of 25 common crane fecal samples and performed analyses in conjunction with supplementary feeding. The results showed that common cranes preferred plants of the families Poaceae and Cyperaceae, similar to common cranes in other nature reserves. Before supplementary feeding, Poaceae and Cyperaceae accounted for 43.83 ± 20.58% and 53.51 ± 19.24%, respectively, while after that, they accounted for 61.23 ± 35.19% and 24.07 ± 28.20%, respectively. The relative abundance of Hordeum increased significantly in January, accounting for 33.88 ± 31.32%, which was mainly affected by supplementary feeding. Therefore, under supplementary feeding, foraging grounds and feeding preferences of common cranes may change correspondingly. The quantity of corn kernels and wheat grains can be increased appropriately in supplementary feeding measures in the nature reserve, and more supplementary feeding sites should be set up in response to the shortage of wild bird food resources. This study applied an effective method to study the diet preference of common cranes under supplementary feeding and further provided insights to improve management measures in the nature reserve.

Introduced Grey Squirrels subvert supplementary feeding of suburban wild birds

Providing food for wild birds is perhaps the most widespread intentional interaction between people and wildlife. In the UK, almost half of households feed wild birds, often as peanuts and seed supplied in hanging feeders. Such food is also taken by the introduced, invasive Grey Squirrel Sciurus carolinensis. Little is known of how Grey Squirrels utilise this resource and how they affect feeder use by wild birds. To assess this we recorded the numbers and time spent by animals visiting experimental feeding stations in suburban gardens, and also asked if exclusionary guards (to prevent Grey Squirrel access), food type (peanut, mixed seed), habitat and weather conditions influenced visits. Using automated cameras, we recorded 24,825 bird and 8577 Grey Squirrel visits. On average >44% of the time feeders were utilised, they were being visited by Grey Squirrels. Grey Squirrel presence prevented birds from feeding at the same time (>99.99%). Feeders where Grey Squirrels were dominant were less likely to be visited by birds, even in their absence. Guards reduced Grey Squirrel use to a minimum on seed feeders, and by approximately half on peanut feeders. Squirrels, food type, guard status, habitat and rainfall all influenced bird activity and timing of feeder visits. Our work suggests that Grey Squirrels reduce the availability of supplementary food to wild birds, while gaining large volumes of food resources with corresponding benefits. Given the ubiquity of supplementary feeding, it is likely that this is an important resource for urban Grey Squirrels; feeder guards mitigate this effect.

Effects of winter food provisioning on the phenotypes of breeding blue tits.

Throughout the Western World, huge numbers of people regularly supply food for wild birds. However, evidence of negative impacts of winter feeding on future reproduction has highlighted a need to improve understanding of the underlying mechanisms shaping avian responses to supplementary food. Here, we test the possibility that carry‐over effects are mediated via their impact on the phenotypes of breeding birds, either by influencing the phenotypic structure of populations through changes in winter survival and/or by more direct effects on the condition of breeding birds. Using a landscape‐scale 3‐year study of blue tits (Cyanistes caeruleus), we demonstrate the importance of nutritional composition of supplementary food in determining carry‐over effect outcomes. We show that breeding populations which had access to vitamin E‐rich foods during the previous winter were comprised of individuals with reduced feather carotenoid concentrations, indicative of lower pre‐feeding phenotypic condition, compared to fat‐fed and unfed populations. This suggests that supplementary feeding in winter can result in altered population phenotypic structure at the time of breeding, perhaps by enhancing survival and recruitment of lower quality individuals. However, supplementation of a fat‐rich diet during winter was detrimental to the oxidative state of breeding birds, with these phenotypic differences ultimately found to impact upon reproductive success. Our findings demonstrate the complex nature by which supplementary feeding can influence wild bird populations.

Health hazards to wild birds and risk factors associated with anthropogenic food provisioning.

Provision of supplementary food for wild birds at garden feeding stations is a common, large-scale and year-round practice in multiple countries including Great Britain (GB). While these additional dietary resources can benefit wildlife, there is a concomitant risk of disease transmission, particularly when birds repeatedly congregate in the same place at high densities and through interactions of species that would not normally associate in close proximity. Citizen science schemes recording garden birds are popular and can integrate disease surveillance with population monitoring, offering a unique opportunity to explore inter-relationships between supplementary feeding, disease epidemiology and population dynamics. Here, we present findings from a national surveillance programme in GB and note the dynamism of endemic and emerging diseases over a 25-year period, focusing on protozoal (finch trichomonosis), viral (Paridae pox) and bacterial (passerine salmonellosis) diseases with contrasting modes of transmission. We also examine the occurrence of mycotoxin contamination of food residues in bird feeders, which present both a direct and indirect (though immunosuppression) risk to wild bird health. Our results inform evidence-based mitigation strategies to minimize anthropogenically mediated health hazards, while maintaining the benefits of providing supplementary food for wild birds.This article is part of the theme issue ‘Anthropogenic resource subsidies and host–parasite dynamics in wildlife’.

Provision of supplementary food for wild birds may increase the risk of local nest predation

In countries such as the UK, USA and Australia, approximately half of all households provide supplementary food for wild birds, making this the public's most common form of active engagement with nature. Year‐round supplementary feeding is currently encouraged by major conservation charities in the UK as it is thought to be of benefit to bird conservation. However, little is understood about how the provision of supplementary food affects the behaviour and ecology of target and non‐target species. Given the scale of supplementary feeding, any negative effects may have important implications for conservation. Potential nest predators are abundant in urban areas and some species frequently visit supplementary feeding stations. We assess whether providing supplementary food affects the likelihood of nest predation in the vicinity of the feeder, by acting as a point attractant for potential nest predators. We provided feeding stations (empty, peanut feeder, peanut feeder with guard to exclude potential nest predators) in an area of suburban parkland in the UK and monitored the predation rate of eggs placed in artificial nests located at distances that replicated the size of typical suburban gardens. Nest predators (Magpies Pica pica, Grey Squirrels Sciurus carolinensis) were frequent visitors to filled feeders, and predation caused by Magpies, European Jays Garrulus glandarius and Grey Squirrels was significantly higher when nests were adjacent to filled feeders. The presence of a feeder guard did not significantly reduce nest predation. As supplementary feeding is becoming increasingly common during the breeding season in suburban habitats, we suggest that providing point attractants to nest predators at this time may have previously unconsidered consequences for the breeding success of urban birds.

Wild Bird Feeding in an Urban Area: Intensity, Economics and Numbers of Individuals Supported

Feeding wild bird is popular in domestic gardens across the world, with around half of households in the UK, North America and Australia doing so. Nevertheless, there is surprisingly little empirical information on many aspects of the activity. We sought to characterise garden bird feeding in a large UK urban area in two ways. First, we conduct- ed face-to-face questionnaires with a representative cross-section of residents. Just over half fed birds, the majority doing so year-round and at least weekly. Second, a 2-year, longitudinal study recorded all foodstuffs put out by house- holds on every provisioning occasion. In this way, we obtained the first year-round quantitative records of the amounts and types of wild bird food provided in individual gardens. A median of 127 g, equivalent to 628 kcal, was given daily per household (typically consisting of several food types). We estimated the daily cost of this provisioning level to be UK£0.35 per household based on the relative proportions of each food type. Provisioning level was not significantly influenced by weather or season. Comparisons between the data sets revealed significantly less frequent feeding amongst the feeders in the longitudinal study (assumed to be 'keen' feeders owing to their participation in this long- term study and numbers of food types provided) than the face-to-face questionnaire respondents, suggesting that ques- tionnaires relying upon participants' estimates rather than records of provisioning may overestimate actual provision- ing frequency. Assuming 100% uptake, the median provisioning level equates to sufficient supplementary resources across the UK to fully support 196 million individuals of a hypothetical average garden-feeding bird species (based on 10 common UK garden-feeding birds' energy requirements). This compares with an estimated total of 71 million breed- ing individuals of these 10 species in the UK (non-breeding numbers unknown). Taking the lowest provisioning level recorded (101 kcal/day) as a conservative measure, 31 million of these average individuals could theoretically be sup- ported.

Supplementary feeding of wild birds indirectly affects ground beetle populations in suburban gardens

Supplementary feeding of wild birds by domestic garden-holders is a globally widespread and popular form of human–wildlife interaction, particularly in urban areas. Vast amounts of energy are thus being added to garden ecosystems. However, the potential indirect effects of this activity on non-avian species have been little studied to date, with the only two previous studies taking place under experimentally manipulated conditions. Here we present the first evidence of a localised depletive effect of wild bird feeding on ground beetles (Coleoptera: Carabidae) in suburban gardens under the usual feeding patterns of the garden-holders. We trapped significantly fewer ground beetles directly under bird-feeding stations than in matched areas of habitat away from feeders. Video analysis also revealed significantly higher activity by ground-foraging birds under the feeding stations than in the control areas. Small mammal trapping revealed no evidence that these species differ in abundance between gardens with and without bird feeders. We therefore suggest that local increases in ground-foraging activity by bird species whose diets encompass arthropods as well as seed material are responsible for the reduction in ground beetle numbers. Our work therefore illustrates that providing food for wild birds can have indirect negative effects on palatable prey species under typical conditions.

Pesticides Firm Hit With Record Fine

Scotts Miracle-Gro will pay the largest criminal fine—$4 million—and the largest civil penalty—$6 million—ever assessed for violations of the federal pesticides law. A major producer of pesticides for lawn and garden use that also sells wild bird food, Scotts agreed to the fines as part of a criminal plea agreement in a federal court case and a civil settlement with the Environmental Protection Agency. Both deals were finalized on Sept. 7. In the criminal case, court papers show that the company pleaded guilty to 11 charges, including creating phony pesticide registration documents. A former employee who fabricated those registration documents between 2004 and 2007 has also pleaded guilty in a separate criminal case and awaits sentencing. Scotts has admitted to having treated stored wild bird food with two insecticides not authorized for this use, including one labeled as toxic to birds, the court documents say. Two employees—a chemist and an ...

Epidemiology of a Salmonella enterica subsp. enterica Serovar Typhimurium Strain Associated with a Songbird Outbreak

Salmonella enterica subsp. enterica serovar Typhimurium is responsible for the majority of salmonellosis cases worldwide. This Salmonella serovar is also responsible for die-offs in songbird populations. In 2009, there was an S. Typhimurium epizootic reported in pine siskins in the eastern United States. At the time, there was also a human outbreak with this serovar that was associated with contaminated peanuts. As peanuts are also used in wild-bird food, it was hypothesized that the pine siskin epizootic was related to this human outbreak. A comparison of songbird and human S. Typhimurium pulsed-field gel electrophoresis (PFGE) patterns revealed that the epizootic was attributed not to the peanut-associated strain but, rather, to a songbird strain first characterized from an American goldfinch in 1998. This same S. Typhimurium strain (PFGE type A3) was also identified in the PulseNet USA database, accounting for 137 of 77,941 total S. Typhimurium PFGE entries. A second molecular typing method, multiple-locus variable-number tandem-repeat analysis (MLVA), confirmed that the same strain was responsible for the pine siskin epizootic in the eastern United States but was distinct from a genetically related strain isolated from pine siskins in Minnesota. The pine siskin A3 strain was first encountered in May 2008 in an American goldfinch and later in a northern cardinal at the start of the pine siskin epizootic. MLVA also confirmed the clonal nature of S. Typhimurium in songbirds and established that the pine siskin epizootic strain was unique to the finch family. For 2009, the distribution of PFGE type A3 in passerines and humans mirrored the highest population density of pine siskins for the East Coast.

Supplementary feeding of wild birds indirectly affects the local abundance of arthropod prey

Providing supplementary food for wild birds is a globally popular pastime; almost half of the households in many developed countries participate and billions of US dollars are spent annually. Although the direct influence of this additional resource on bird survivorship and fecundity has been studied, there is little understanding of the wider ecological consequences of this massive perturbation to (what are usually) urban ecosystems. We investigated the possible effects of wild bird feeding on the size and survivorship of colonies of a widespread arthropod prey species of many small passerine birds, the pea aphid [Acyrthosiphon pisum (Harris); Hemiptera: Aphididae], in suburban gardens in a large town in southern England. We found significantly fewer aphids and shorter colony survival times in colonies exposed to avian predation compared to protected controls in gardens with a bird feeder but no such differences between exposed and protected colonies in gardens that did not feed birds. Our work therefore suggests that supplementary feeding of wild birds in gardens may indirectly influence population sizes and survivorship of their arthropod prey and highlights the need for further research into the potential effects on other species.

Lowland Farmland Birds III: Delivering Solutions in an Uncertain World. A report on the BOU’s Annual Conference held at the University of Leicester, 31 March–2 April 2009

Lowland Farmland Birds III: Delivering Solutions in an Uncertain World. A report on the BOU’s Annual Conference held at the University of Leicester, 31 March–2 April 2009

On Rats, Refuse, and Recycling

They say that no one is more than a few feet away from a rat, in town or country. In the UK, the distance must be shrinking year by year. The latest National Rodent Survey reveals that, between the reporting years 1998/1999 and 2004/2005, the increase in numbers was three times higher for rats (39%) than for mice (12.5%).1 These are not pets (white rats) but the brown rat, or Rattus norvegicus. The survey also counts “summer rats,” up by 69%, not because this is a different species but because of a concern that the seasonal pattern of R. norvegicus sightings has changed. Improved standards of human living do not appear to be affecting rat populations in the UK for the better, and a similar picture has been described for Baltimore, MD, where a rat population of 48,420 was estimated in 2004, this being little changed from half a century earlier.2 The UK’s National Pest Technicians Association (NPTA) highlights six factors contributing to the increase.1 These are not unique to cities, but somehow, rats in the countryside are acceptable, while in towns they are not. The factors are a mix of the individual and the institutional, and there is the occasional clash between ecofriendly activities and pest control. For example, putting out food for wild birds, if done to excess, results in spills that attract rodents. Composting, which the NPTA refers to mischievously as “recycling mania”, can also encourage rats, if done inappropriately. Urban local authority policies have been causing concern too. The Local Government Association is thinking about charges for refuse collection above a certain weight, and as public refuse disposal becomes more complex with European diktats on recycling, it is not unheard of for rubbish bins to be emptied once a fortnight instead of weekly. This policy may encourage recycling and/or rats, and in the city of Oxford, for example, some residents are not at all happy with the change.3 Waste disposal is now a big issue in the UK, where the average annual weight of nonrecyclable refuse is more than 500 kg per household, far more than in any other country in the European Union.4 Most of this goes to landfill, and sites are running out. Just as carelessly disposed of food waste in cities attracts rats, urban foxes, and birds, so do landfill sites draw gulls far inland from their usual haunts. When refuse collectors go on strike, cities soon become unbearable, and the residues of half-eaten fast-food meals are a regular feature of city streets today. Happily, there have not yet been epidemics of leptospirosis, hantavirus disease, plague, rabies, salmonella, shigella, campylobacter, toxoplasma, or toxacara infections that can be blamed on unwelcome quadripedal or avian urban visitors. However, the ingredients for threats to public health are in place—for example, in Europe a watchful eye is being kept on the urban fox and human alveolar echinococcosis.5,6 What does it take to tilt the urban waste problem from the merely unpleasant to the downright dangerous?

Mycotoxin review - 1. Aspergillus and Penicillium

When a major wild bird food producer advised, in their catalogue for the year 2000, that they could not offer peanuts because of the high levels of aflatoxin, the phenomenon of mycotoxins had really come into the public domain. In 2001 the same company was able to advise that 'Although present in some peanut crops this season, aflatoxin is not currently creating any major peanut supply problems'. Mycotoxins, and specifically peanuts and the health of wild birds, were reviewed in earlier volumes of this journal (Isaac 1994 a, b ) but the passage of time has not led to any reduction in the problems associated with the presence of mycotoxins in foods and animal feeds. Indeed, the improvement in analytical methods, and the implications of legislation in many countries have served to increase awareness of mycotoxins.

Causes of death of wild birds of the family Fringillidae in Britain

The provision of supplementary food for wild birds in gardens during the winter months is common in the UK, but it is possible that it may precipitate infectious diseases in...

Determination of mycotoxins in pet foods sold for domestic pets and wild birds using linked‐column immunoassay clean‐up and HPLC

A technique referred to as ‘linked‐column immunoassay clean‐up’, was developed for the simultaneous determination of aflatoxins and ochratoxin A in a range of dry cereal‐based pet foods and wild bird food. In addition a method also based on clean‐up using immunoaffinity columns was used for the determination of fumonisin mycotoxins in samples known or suspected to contain maize. One hundred samples of pet foods consisting of 35 samples each of cereal‐based dog and cat foods, 15 samples of domestic bird seeds and 15 samples of wild bird food were examined for aflatoxins B1 B2, G1 and G2 and ochratoxin A. Twenty samples of these samples were also examined for fumonisins B1 and B2. Limits of detection were about 0.5 μg/kg for each aflatoxin and ochratoxin A and 3 and 8 μg/kg for fumonisins B1 and B2 respectively. Eighty‐four percent of the samples contained no measurable concentrations of mycotoxins. A low level of aflatoxin B1 was found in a sample of cat food and a concentration of 370 μg/kg aflatoxin B1 in one sample of peanuts marketed for wild birds. Ochratoxin A was detected in 10% of samples but in low concentrations, the highest of 7 μg/kg occurring in a sample of bird food. Fumonisins were found in 30% of the 20 samples tested with a maximum of 750 μg/kg total fumonisins being found in a sample of cat food. Five samples each of dog and cat foods were examined for mould count and fungal species as received and after storage under controlled simulated damp conditions. Mould counts in all 10 samples examined were very low when received. The samples in which moisture content had been increased contained visible mould after storage. Penicillium, Eurotium and Aspergillus were the predominant species. However, no ochratoxin A or aflatoxins were detected in these spoiled samples.

Toxicity of High Levels of Zinc-65 to Avian Embryos

THE problems of specific reactor-produced radionuclides from water used for cooling reactors are expected to increase as the use of nuclear power increases. Radioanalyses of fish sampled from the Columbia River and from the Pacific Ocean off the Oregon Coast indicate that 65 Zn is one of the most abundant radionuclides identified (muscle tissue of the Columbia River whitefish averaged 38 pCi./g. in 1963). While 1,000 times the levels found did not affect trout, 105 μCi. 65 Zn at the rate of 10 μCi./g. fish per day produced leucopenia and apparent damage to the gill filaments (Nakatani et al., 1965). Since fish and shellfish are important sources of food for wild birds, as well as domesticated ones, a knowledge of the effect of prolonged or continuous irradiation from 65 Zn in the avian species is needed. The chick embryo is particularly suited for this study as it is completely divorced from maternal considerations…