Garden Birds Research Articles

Supplementary feeding of the reintroduced Red Kite Milvus milvus in UK gardens

Capsule The provision of meat for garden birds is unusual in the UK but a reintroduced raptor, the Red Kite Milvus milvus, is now regularly fed in some areas. A questionnaire of garden kite feeders revealed that people were most often motivated to feed by a desire to see kites close up and that most provisioning falls within available guidelines. We estimated the median amount of food thought to be taken by kites per kite-feeding garden per day as 21 g, sufficient to support 0.12–0.26 individuals.

Epidemiological Evidence That Garden Birds Are a Source of Human Salmonellosis in England and Wales

The importance of wild bird populations as a reservoir of zoonotic pathogens is well established. Salmonellosis is a frequently diagnosed infectious cause of mortality of garden birds in England and Wales, predominantly caused by Salmonella enterica subspecies enterica serovar Typhimurium definitive phage types 40, 56(v) and 160. In Britain, these phage types are considered highly host-adapted with a high degree of genetic similarity amongst isolates, and in some instances are clonal. Pulsed field gel electrophoresis, however, demonstrated minimal variation amongst matched DT40 and DT56(v) isolates derived from passerine and human incidents of salmonellosis across England in 2000–2007. Also, during the period 1993–2012, similar temporal and spatial trends of infection with these S. Typhimurium phage types occurred in both the British garden bird and human populations; 1.6% of all S. Typhimurium (0.2% of all Salmonella) isolates from humans in England and Wales over the period 2000–2010. These findings support the hypothesis that garden birds act as the primary reservoir of infection for these zoonotic bacteria. Most passerine salmonellosis outbreaks identified occurred at and around feeding stations, which are likely sites of public exposure to sick or dead garden birds and their faeces. We, therefore, advise the public to practise routine personal hygiene measures when feeding wild birds and especially when handling sick wild birds.

Squirrels in suburbia: influence of urbanisation on the occurrence and distribution of a common exotic mammal

Urbanisation is widely considered to promote the establishment of non-native species, but there is limited empirical evidence of the ecological factors driving their responses. The grey squirrel Sciurus carolinensis (Gmelin 1788) is native to North America, but is widespread in the UK and is starting to spread across Europe. It is regarded as one of the world’s worst invasive animals due to its adverse impacts on native biodiversity. We use the non-native grey squirrel population in Sheffield (UK) as a case study to assess which factors limit its distribution and abundance in urban environments. In 2010 the city-wide population of adult squirrels peaked at an estimated 6539 in autumn (0.46 squirrels/ha), with maximum local densities of 8.29/ha. These densities appear to be slightly lower than those recorded in urban environments in the species’ native range. Grey squirrels occurred more frequently at urban sites with larger amounts of green-space in the surrounding region. Local habitat characteristics were, however, more powerful predictors of urban grey squirrel occurrence and abundance than regional availability of green space. Canopy cover, seed bearing trees and supplementary feeders, provided for garden birds, positively influenced grey squirrels. The potential for grey squirrels to connect city dwellers with nature thus appears to be highest in urban locations that have considerable capacity to support native biodiversity. The beneficial impacts of supplementary feeding on grey squirrel populations is notable given concerns that squirrels can adversely influence bird populations. These habitat associations also imply that grey squirrels typically respond negatively to urbanisation, which challenges arguments that urbanisation favours exotic species.

Wild birds carry similar Salmonella enterica serovar Typhimurium strains to those found in domestic animals and livestock

The objective of this study was to investigate the hypothesis that some sporadic Salmonella infections in domesticated animals may be associated with Salmonella infections originating from garden birds. Phage type and antimicrobial resistance details of isolates of S. Typhimurium obtained from wild birds were comparable with those from S. Typhimurium infections from domesticated animals or livestock between 2002 and 2010. A small panel of S. Typhimurium isolates (n=37) were characterised by multilocus variable number of tandem repeats analysis (MLVA), pulsed field gel electrophoresis (PFGE) and phage type. The MLVA-PFGE data clustered the strains according to phage type (DT40 or DT56). Within each group there were strains from wild birds and domesticated animals or livestock with MLVA profiles having up to 100% similarity. The results from this study therefore lend support to the hypothesis that Salmonella infections in domesticated animals could be caused by infections carried by wild birds.

Fat provisioning in winter impairs egg production during the following spring: a landscape‐scale study of blue tits

1. Provisioning of garden birds is a growing phenomenon, particularly during winter, but there is little empirical evidence of its true ecological impacts. One possibility is that winter provisioning could enhance subsequent breeding performance, but this seems likely to depend on the types of nutrients provided. For example, whereas effects of macronutrients such as fat are unlikely to be carried over to influence breeding in small passerines, micronutrients such as dietary vitamin E (an antioxidant) may be stored or have lasting health benefits. 2. Here, we examine the carry-over effects of winter food supplements on egg production in wild populations of blue tits (Cyanistes caeruleus). Over three consecutive years, birds were provisioned with fat, fat plus vitamin E or remained unfed (controls). 3. The provision of fat in winter resulted in smaller relative yolk mass in larger eggs and reduced yolk carotenoid concentrations in early breeders. However, these effects were not seen in birds provisioned with fat plus vitamin E. Lay date, clutch size, egg mass and yolk vitamin E concentrations were not significantly affected by winter provisioning treatment. 4. Our results indicate that winter provisioning can have important downstream consequences, in particular affecting investment in egg production several weeks or months later. 5. Provisioning is widely applied to support garden bird populations and for the conservation management of endangered species. However, our results challenge the assumption that such practices are always beneficial at the population level and emphasize how the ecological impacts can depend on the specific nutritional profile of provisioned foods.

Spotting garden birds in winter

The RSPB holds its Big Garden Bird Watch in January, so why not use the event as a basis for planning fun activities, that access each of the prime and specific areas of learning.

Emergence of a novel avian pox disease in British tit species.

Avian pox is a viral disease with a wide host range. In Great Britain, avian pox in birds of the Paridae family was first diagnosed in a great tit (Parus major) from south-east England in 2006. An increasing number of avian pox incidents in Paridae have been reported each year since, indicative of an emergent infection. Here, we utilise a database of opportunistic reports of garden bird mortality and morbidity to analyse spatial and temporal patterns of suspected avian pox throughout Great Britain, 2006–2010. Reports of affected Paridae (211 incidents) outnumbered reports in non-Paridae (91 incidents). The majority (90%) of Paridae incidents involved great tits. Paridae pox incidents were more likely to involve multiple individuals (77.3%) than were incidents in non-Paridae hosts (31.9%). Unlike the small wart-like lesions usually seen in non-Paridae with avian pox in Great Britain, lesions in Paridae were frequently large, often with an ulcerated surface and caseous core. Spatial analyses revealed strong clustering of suspected avian pox incidents involving Paridae hosts, but only weak, inconsistent clustering of incidents involving non-Paridae hosts. There was no spatial association between Paridae and non-Paridae incidents. We documented significant spatial spread of Paridae pox from an origin in south-east England; no spatial spread was evident for non-Paridae pox. For both host clades, there was an annual peak of reports in August/September. Sequencing of the avian poxvirus 4b core protein produced an identical viral sequence from each of 20 great tits tested from Great Britain. This sequence was identical to that from great tits from central Europe and Scandinavia. In contrast, sequence variation was evident amongst virus tested from 17 non-Paridae hosts of 5 species. Our findings show Paridae pox to be an emerging infectious disease in wild birds in Great Britain, apparently originating from viral incursion from central Europe or Scandinavia.

The “Preposterousness” of John Burningham: Complexity Made Accessible

The “Preposterousness” of John Burningham: Complexity Made Accessible Lydia Kokkola (bio) John Burningham, the British candidate for the 2012 Hans Christian Andersen prize for illustration, has been a prolific author-illustrator of picture books, producing more than a book a year for over half a century. His works appeal to children, adults, critics, and teachers in different but overlapping ways. Although he claims “I am not thinking about [children] when I do this at all. I never do anything differently because it’s for children. I am not trying to make a landscape that children can understand. I am just making a landscape” (qtd. in Jones), he is revered precisely for his ability to make complex ideas and emotions accessible to his young readers. Click for larger view View full resolution Burningham’s debut picture book was Borka: The Adventures of a Goose with No Feathers (1963), and it remains one of his most loved picture books with its delicious blend of realism and fantasy. Borka the goose is born without feathers, and so her mother knits her a grey woolen jumper to keep her warm, but she can never learn to fly. So when her companions migrate, Borka must make her way down the British coast without flying. She boards a ship and earns her passage by coiling ropes and picking up crumbs. She finally makes a home for herself amongst the other unusual birds in Kew Gardens. The key to Borka’s success, as Brian Alderson explains, is that the “low-key presentation of these preposterous events helps to suggest a complete normality.” This suggestion is evident not only in the story lines, but also in the illustrative technique as slightly different techniques are used to distinguish the “preposterous” from the expected. In the 1970s, the division is made manifest in Burningham’s two books about Shirley: Come Away from the Water, Shirley (1977) and Time to Get Out of the Bath, Shirley (1978). These counterpoint picture books use the gutter to separate the mundane world of the adult from the imaginative interior world of the child’s [End Page 56] imagination. So while Shirley’s parents focus on the prosaic concerns of the coldness of the seawater or bath water on the floor, Shirley imagines herself into a fantasy world where she can fight pirates and find treasure. Her parents are depicted in subdued sketches lightly washed with color, images which only lightly intimate the adults’ physical environment and so suggest they are out of touch with what is going on around them. Shirley, by way of contrast, is depicted in thickly painted mauves, pinks and yellows, and mixed media is incorporated to add further texture to these imagined environs. She is deeply connected to her imagined environment. Despite her silence (we only read what her mother says, never what Shirley has to say or think), Shirley’s feisty adventures demonstrate she does not lack autonomy. Shirley’s parents “are easy prey for the satirist or the social critic, but they are in Burningham-land where the criteria are different. The reader does not despise so much as feel sorry for them” (Alderson). And herein lies Burningham’s main contribution to children’s literature. He takes a deeply complex subject—in this case a parent-child relationship that seems somewhat awry even though it is far from abusive or uncaring—and he makes it, not simple, but accessible. To make it simple would be to remove the subtle nuances, to treat the child reader as being incapable of understanding the complexities of their own lives. Instead, Burningham celebrates the complexity of the child’s emotional world without taking cheap shots at the adults in their lives. The same standards apply in the opposite direction when Burningham explores the so-called “bad” behavior of children. Julius, the child character of Where’s Julius? (1986) never manages to join his parents for their well-cooked, varied meals because he is always off having imaginative adventures and exploring. Instead of berating their son, Julius’s father patiently brings his son meals to eat in the exotic fantasy worlds Julius has created. At the end of the book, Julius is ready...

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.

Pulsed-field gel electrophoresis supports the presence of host-adapted Salmonella enterica subsp. enterica serovar Typhimurium strains in the British garden bird population.

Salmonellosis is a frequently diagnosed infectious disease of passerine birds in garden habitats within Great Britain with potential implications for human and domestic animal health. Postmortem examinations were performed on 1,477 garden bird carcasses of circa 50 species from England and Wales, 1999 to 2007 inclusive. Salmonellosis was confirmed in 263 adult birds of 10 passerine species in this 11-year longitudinal study. A subset of 124 fully biotyped Salmonella enterica subsp. enterica serovar Typhimurium isolates was examined using pulsed-field gel electrophoresis to investigate the hypothesis that these strains are host adapted and to determine whether this molecular technique offers greater resolution in understanding the epidemiology of Salmonella Typhimurium infection than phage typing alone. For the two most common phage types, definitive type (DT) 40 and DT56v, which together accounted for 97% (120/124) of isolates, pulsed-field gel electrophoresis groupings closely correlated with phage type with remarkably few exceptions. A high degree of genetic similarity (>90%) was observed within and between the two most common pulsed-field gel electrophoresis groups. No clustering or variation was found in the pulsed-field gel electrophoresis groupings by bird species, year, or geographical region beyond that revealed by phage typing. These findings support the hypothesis that there are currently two host-adapted Salmonella phage types, S. Typhimurium DT40 and DT56v, circulating widely in British garden birds and that the reservoir of infection is maintained within wild bird populations. Large-scale multilocus sequence typing studies are required to further investigate the epidemiology of this infection.

Do heterospecific size and demeanour influence visitation behaviour of birds at urban foraging patches?

We compared the feeding behaviour of garden birds in the presence of four heterospecific decoy species at suburban feeding stations to assess the relative importance of body size (large vs. small) and demeanour (high vs. low potential for inter-specific aggression) as cues for threat recognition. We conducted separate trials with live, caged Australian magpie, Cracticus tibicen, and common myna, Acridotheres tristis, large and small species known to chase and harass heterospecifics, and comparably sized species not known for inter-species aggression (i.e. rock dove, Columba livia, and ringneck dove, Streptopelia risoria). Birds of all species arrived at feeding stations sooner and displayed higher-risk activities in the presence of small decoys. The two most common species that visited the feeding stations, silvereye, Zosterops lateralis, and house sparrow, Passer domesticus, were most likely to perform high-risk behaviours (i.e. landing on the stimulus cage and feeding from the station) in the presence of common mynas. The activities were performed least frequently in the presence of Australian magpies. As garden birds likely had the most experience interacting with common mynas, the results suggest that a two-step decision rule, with size and familiarity as important cues, may be used to recognize potential threats.

The presence of Mycobacterium avium subsp. avium in common pheasants (Phasianus colchicus) living in captivity and in other birds, vertebrates, non-vertebrates and the environment

Although avian mycobacteriosis is not prevalent among domestic fowl used for intensive husbandry, it has been described in both free living birds and birds in captivity, e.g., zoological gardens and small fowl flocks. In this study, we examined 305 pheasants from six flocks as well as 70 other birds belonging to 14 species and 97 other vertebrates caught in a closed area. We also investigated the prevalence of mycobacteria in non-vertebrates (earthworms) and soil in two pheasant flocks. Mycobacterium avium subsp. avium (M. a. avium) was isolated in four flocks from 17 (5.6%) pheasants. In one M. a. avium-infected pheasant co-infection with M. a. hominissuis was diagnosed. Granulomatous inflammatory lesions were observed in liver and spleen in only four M. a. avium-infected pheasants originating from two flocks. From the other 38 pheasants other mycobacterial species were isolated, such as M. fortuitum, M. terrae, M. triviale, M. chelonae, M. scrofulaceum, M. smegmatis, M. flavescens, M. diernhoferi and non-identifiable mycobacterial species. In the group of 70 birds of other species, we identified M. a. avium in two (2.9%) goshawks (Accipiter gentilis). We did not isolate M. a. avium from any of the other 97 vertebrates, the 391 environment samples or 97 earthworms.

Dynamics of garden birds at a feeding station in a suburban area near Oslo, Norway, 2000–2008

The presence of birds visiting a feeding site near a villa in a suburban area to the west of Oslo was observed daily at close range during 2000–2008. The bird assemblage consisted of 17 species. Some species were present throughout the year, whereas others occurred during different seasons. Most species showed a stable occurrence from year to year and was little influenced by climatic factors. When comparing with the bird community in a spruce forest about three kilometres away, only 36% of the forest species occurred regularly at the suburban site, showing a considerable loss of diversity when a forest is changed into a suburban habitat. Abundance was recorded by the time it took the birds to consume one kilo of sunflower seeds. Maximum consumption occurred during summer and minimum during late winter. A general decrease in consumption in all years of study started during autumn followed by another marked decrease at the time of the first snowfall, which obviously acted as a signal for emigration out of the area.

Wild bird feeding delays start of dawn singing in the great tit

Supplementary feeding of wild birds during winter is one of the most popular wildlife management activities, and is likely to have profound influence on the behavioural ecology of a species. At garden bird feeders, birds are now often fed well into the breeding season. Providing food within an established songbird territory, however, is likely to influence the territorial behaviour of the resident male. We used song performance during the dawn chorus in early spring to study behavioural changes in food-supplemented great tits, Parus major. After 2 weeks of continuous food supply within their territory, supplemented males started dawn singing later than control males, and thus postponed their regular dawn chorus before sunrise. This effect was maintained 2 weeks after food supplementation had ended. However, we did not find an effect of long-term feeding on song output. Our results were largely unexpected because formal models and field studies on short-term food supplementation suggested an earlier start of dawn singing or a higher dawn song output. Because we did not observe great tits visiting the feeders before sunrise or food supplementation increasing the numbers of conspecific intruders, the reasons for the delay in the start of dawn singing remain unclear; possible explanations include the presence of predators at feeding stations and the quality of the supplementary food itself. Delaying dawn singing could potentially affect the reproductive success of supplemented males, for example if females base extrapair mating decisions on dawn song performance of their mates.

Site fidelity and longevity of the Karoo Thrush Turdus smithi (Bonaparte 1850) in an urban environment

Turdus smithi, formerly a subspecies of T. olivaceus, has been elevated to species status, resulting in a void in our knowledge on this species. Although both T. smithi and T. olivaceus are common garden birds throughout their ranges, most studies to date have focused on T. olivaceus. These studies found that T. o. olivaceus reach ages in excess of 11 years and maintain territories of 10 000–13 000 m2. The present study investigated site fidelity and longevity of an urban T. smithi population at the University of Pretoria main campus in Gauteng. Thrushes were ringed with unique colour ring combinations and identified by resighting them later. We found that T. smithi individuals have high site fidelity, with some thrushes being present in their same home ranges nearly nine years after being ringed, and suspect that they occupied these territories continuously between ringing and resighting. We found that T. smithi maintain larger home ranges than T. olivaceus individuals, and have a similar maximum longevity. We propose that adult thrushes are able to persist in a given home range because they are able to avoid resident predators, e.g. feral cats Felis sylvestris catus, by accurately predicting their hunting strategies.

Epidemiology of Salmonellosis in Garden Birds in England and Wales, 1993 to 2003

Salmonellosis has been reported as an important cause of mortality of garden birds in several countries, including Norway and Scotland. We investigated the frequency of the disease in garden birds submitted for postmortem examination by members of the public in England and Wales between 1993 and 2003, inclusive. We found salmonellosis to be the most frequent cause of death due to infectious disease in the garden birds submitted. This disease was confirmed in 7 of the 45 bird species that were examined postmortem, with the greenfinch (Carduelis chloris) and the house sparrow (Passer domesticus) most frequently affected. Salmonella Typhimurium definitive phage type (DT) 40, DT56 variant(v), and DT160 accounted for the majority of isolates. Salmonellosis incidents chiefly occurred in the English Midlands, the English/Welsh border region, and southern England. Variation in the temporal and spatial distribution of the phage types occurred over the study period. While birds were examined throughout the year, there was a marked winter seasonality in salmonellosis. A significant sex bias was observed in affected greenfinches, with males more frequently diagnosed with salmonellosis than females. No sex bias was observed for other affected species. Further research is required to determine if salmonellosis is an important constraint to the populations of affected species and if disease outbreaks are driven by human factors, such as provisioning.

Multi-locus sequence typing of Salmonella enterica serovar Typhimurium isolates from wild birds in northern England suggests host-adapted strain

Recent studies have suggested that Salmonella Typhimurium strains associated with mortality in UK garden birds are significantly different from strains that cause disease in humans and livestock and that wild bird strains may be host adapted. However, without further genomic characterization of these strains, it is not possible to determine whether they are host adapted. The aim of this study was to characterize a representative sample of Salm. Typhimurium strains detected in wild garden birds using multi-locus sequence typing (MLST)to investigate evolutionary relationships between them. Multi-locus sequence typing was performed on nine Salm. Typhimurium strains isolated from wild garden birds. Two sequence types were identified, the most common of which was ST568. Examination of the public Salmonella enterica MLST database revealed that only three other ST568 isolates had been cultured from a human in Scotland. Two further isolates of Salm. Typhimurium were determined to be ST19. Results of MLST analysis suggest that there is a predominant strain of Salm. Typhimurium circulating among garden bird populations in the United Kingdom, which is rarely detected in other species, supporting the hypothesis that this strain is host adapted. Host-pathogen evolution is often assumed to lead to pathogens becoming less virulent to avoid the death of their host; however, infection with ST568 led to high mortality rates among the wild birds examined, which were all found dead at wild bird-feeding stations. We hypothesize that by attracting unnaturally high densities of birds, wild bird-feeding stations may facilitate the transmission of ST568 between wild birds, therefore reducing the evolutionary cost of this pathogen killing its host, resulting in a host-adapted strain with increased virulence.

Acute necrotising pneumonitis associated with Suttonella ornithocola infection in tits (Paridae)

Suttonella ornithocola, first isolated from the lungs of British tit species in 1996, was found to be a novel bacterium belonging to the family Cardiobacteriaceae. Comprehensive surveillance of garden bird mortality across Great Britain between April 2005 and April 2009 involved post mortem and microbiological examination of 82 tits (Paridae; multiple species) and six long-tailed tits (Aegithalidae; Aegithalos caudatus). S. ornithocola was isolated from six birds submitted from six incidents of morbidity and mortality involving Paridae and Aegithalidae species with a wide geographical distribution. The mortality incidents occurred sporadically at low incidence throughout the study period, which suggested that the infection is endemic in native bird populations, with a seasonal peak during early spring. Histopathological examination showed multiple foci of acute pulmonary necrosis associated with gram-negative cocco-bacillary bacteria. These findings supported the hypothesis that S. ornithocola is a primary pathogen of tits in Great Britain.

Salmonellosis in garden birds in Scotland, 1995 to 2008: geographic region, Salmonella enterica phage type and bird species

Salmonellosis was diagnosed in garden birds from 198 incidents in Scotland between September 1995 and August 2008. Salmonellosis was essentially a disease of finches in the north of Scotland, but...

Birds select conventional over organic wheat when given free choice

Global demand for organic produce is increasing by euro4 billion annually. One key reason why consumers buy organic food is because they consider it to be better for human and animal health. Reviews comparing organic and conventional food have stated that organic food is preferred by birds and mammals in choice tests. This study shows the opposite result-that captive birds in the laboratory and wild garden birds both consumed more conventional than organic wheat when given free choice. There was a lag in preference formation during which time birds learnt to distinguish between the two food types, which is likely to explain why the present results differ from those of previous studies. A further experiment confirmed that, of 16 potential causal factors, detection by birds of consistently higher levels of protein in conventional seeds (a common difference between many organic and conventional foodstuffs) is the likely mechanism behind this pattern. The results of this study suggest that the current dogma that organic food is preferred to conventional food may not always be true, which is of considerable importance for consumer perceptions of organically grown food.