Local Birds Research Articles

Determining the boundaries of migratory bird flyways: a Bayesian model for Eurasian teal Anas crecca in western Europe

Accurate flyway delineation is a prerequisite for effective conservation and management of migratory bird populations, yet such limits have so far mostly been set subjectively. We present a statistical method to infer population boundaries from the analysis of ring recoveries, using a Bayesian framework. The approach was applied to Eurasian teal Anas crecca ringed in Camargue, southern France, and Abberton Reservoir, Essex, eastern England. The results presented show the boundaries of the two teal flyways in western Europe, with a zone of overlap, broadly matching those previously defined. The percentage of teal switching flyways (abmigration rate) was 2.4–2.6%, greater in birds ringed as juveniles than as adults. Abmigrants ended up at sites within the other flyway where the density of local birds was lower than expected by chance, suggesting abmigration resulted from exploratory or aberrant behaviour. The methodology presented here can be used to infer flyway boundaries of any bird with an adequate ring‐re‐encounter dataset, which has crucial consequences for the evaluation of their trends in abundance and hence conservation status, and the management of sustainable harvests.

Vertebrate diversity benefiting from carrion provided by pumas and other subordinate, apex felids

Carrion promotes biodiversity and ecosystem stability, and large carnivores provide this resource throughout the year. In particular, apex felids subordinate to other carnivores contribute more carrion to ecological communities than other predators. We measured vertebrate scavenger diversity at puma (Puma concolor) kills in the Greater Yellowstone Ecosystem, and utilized a model-comparison approach to determine what variables influenced scavenger diversity (Shannon's H) at carcasses. We documented the highest vertebrate scavenger diversity of any study to date (39 birds and mammals). Scavengers represented 10.9% of local birds and 28.3% of local mammals, emphasizing the diversity of food-web vectors supported by pumas, and the positive contributions of pumas and potentially other subordinate, apex felids to ecological stability. Scavenger diversity at carcasses was most influenced by the length of time the carcass was sampled, and the biological variables, temperature and prey weight. Nevertheless, diversity was relatively consistent across carcasses. We also identified six additional stalk-and-ambush carnivores weighing >20kg, that feed on prey larger than themselves, and are subordinate to other predators. Together with pumas, these seven felids may provide distinctive ecological functions through their disproportionate production of carrion and subsequent contributions to biodiversity. We urge conservation managers to increase support for these species, as a means of prioritizing resources to best ensure the persistence of carrion in natural systems.

A whole cell bio-optode based on immobilized nitrite-degrading microorganism on the acrylic microspheres for visual quantitation of nitrite ion

Abstract A microspheres-based microbial optosensor for NO 2 − ion quantitation was constructed by using immobilized Raoutella planticola ( R. planticola ), the bacterium expressing NAD(P)H nitrite reductase (NiR) enzyme, which was isolated from local edible bird’s nest (EBN) via microbial technique. The whole cells and the lipophilic Nile Blue chromoionophore (NBC) were physically adsorbed on the self-adhesive photocurable poly( n -butyl acrylate-co- N -acryloxysuccinimide) [poly(nBA-NAS)] microspheres, whilst the reduced co-enzyme NAD(P)H was covalently immobilized on the succinimide-functionalized acrylic microspheres via peptide link to produce a reagentless nitrite biosensing system. As the microbial bio-optode responded to nitrite through colour change from blue to pink, a facile reflectometric approach was adopted to measure reflectance intensity at 639 nm, before and after reaction with nitrite at optimum pH 8. The optosensor could quantify NO 2 − ion concentration within a dynamic linear response range of 0.5–400 mg L −1 with a limit of detection (LOD) of 0.2 mg L −1 . The large surface area to volume ratio of the acrylic microspheres allowed solid-state diffusional mass transfer of the substrate to occur at micro-bio-optode surface, and an equilibrium response was achieved within 5 min. The practical feasibility of using the bio-optode for nitrite assay in food matrix sample showed good agreement with standard ion chromatography method.

Outbreaks of Mycoplasmosis and Histomoniasis in a Southern Brazilian Flock of Ornamental Birds

Background: Infectious diseases have expanded their host and geographic ranges, increasing impacts on both human and animal health. Mycoplasma gallisepticum usually causes avian chronic respiratory conditions and Histomonas meleagridis infects the cecum and the liver of poultry. Although these diseases have been reported in several bird species, information associated with their prevalence and impact in local flocks of ornamental birds is scarce. This communication describes severe outbreaks of mycoplasmosis and histomoniasis that affected a southern Brazilian commercial flock of ornamental birds.Case: The outbreaks occurred in an ornamental bird flock that contained 2,340 birds from 39 different species, distributed mostly in the orders Galliformes, Anseriformes, and Psittaciformes. Mycoplasma gallisepticum affected 12 chukar partridges, 12 Indian peacocks, 19 ornamental chickens and 46 individuals of 4 species of pheasant. The disease cases were distributed between April and July 2015. A total of 36 birds died due to the disease’ complications and most surviving birds suffered from severe ocular sequels, which determined their subsequent culling, despite attempts of different treatment protocols. The main signs included coughing, sneezing, infraorbital swelling, wasting, and death which were mostly associated with caseous sinusitis. Affected birds had positive samples when stained with anti-Mycoplasma gallisepticum immunohistochemistry and tested by Mycoplasma gallisepticum-Polymerase Chain Reaction. The application of 2 doses of a Mycoplasma gallisepticum vaccine in early 2016 to all the Galliformes in the flock reduced the annual prevalence to 4 clinical cases. Histomoniasis affected and killed 19 out of 27 chukar partridges that were being kept with ring-necked pheasants in the same enclosure. The disease occurred between September and December 2016 and a high prevalence of Heterakis gallinarum was detected in the flock. The main findings included apathy and death linked to hepatic and cecal necrosis. Admixed in the necrotic areas, there were numerous round to oval, eosinophilic, protozoal trophozoites of 15-20 µm in diameter, occasionally containing a 3-5 µm centrally located basophilic nucleus (histomonads) surrounded by a clear halo. Anthelmintic dosing, exchanging and liming the bedding material of the enclosures, and keeping the remaining partridges in an aerial aviary with a wire mesh floor prevented additional cases of histomoniasis.Discussion: In Brazil, as in other countries, the sanitary management practices applied in commercial chicken production reached high levels of technification. However, this is not the case in ornamental bird breeding systems, which may still suffer the impacts of diseases that are practically extinct in industrial chicken flocks. For both diseases, diagnosis was based on typical clinical signs and detection of the pathogens in association with characteristic pathological findings. The occurrence of mycoplasmosis and histomoniasis was associated with improper management practices at the farm; the main risk factors observed were a high turnover of birds, the absence of quarantine, the absence of basic health care, overcrowding and poor hygiene. The prevention of further cases of both diseases was mostly established with the application of basic sanitary measures, including vaccination and anthelmintic dosing, for mycoplasmosis and histomoniasis respectively. This report alerts bird keepers and avian veterinarians of the importance of establishing proper sanitary management in local ornamental bird flocks. Because some of the ornamental bird species that have been commercially propagated worldwide may be included in the list of threatened species, the findings described here also show that simple health care may promote the fight against extinctions.

Avian influenza in Latin America: A systematic review of serological and molecular studies from 2000-2015.

Avian influenza or bird flu is a highly contagious acute viral disease that can occur in epidemics and cross-border forms in poultry and wild birds. The characteristics of avian influenza viruses (AIVs) allow the emergence of new viral variants, some with zoonotic and pandemic potential. AIVs have been identified in Latin America; however, there is a lack of understanding of these viruses at the regional level. We performed a systematic literature review on serological or molecular evidence of AIVs circulation in Latin America. Methods were designed based on the PRISMA and STROME guidelines. Only peer-reviewed studies published between 2000 to 2015 and data was analysed based on country, viral subtype, avian species, and phylogenetic origins. From 271 studies initially found only twenty-six met our inclusion criteria. Evidence of AIVs infection was found in most Latin American countries, with Mexico as the country with the largest number of conducted studies and reported cases during the period analysed, followed by Chile and Argentina. Most of the AIVs were early reported through surveillance systems and at least 14 different subtypes of influenza viruses were reported in birds, and the presence of both low (92.9%) and high (7.1%) pathogenic AIVs was shown in Latin America. Of the reported AIVs in Latin America, 43.7% belong to migratory birds, 28.1% to local wild birds, and 28.1% to poultry. The migratory bird population mainly comprises families belonging to the orders Anseriformes and Charadriformes. We highlight the importance of epidemiological surveillance systems and the possible role of different migratory birds in the transmission of AIVs within the Americas. Our findings demonstrate the limited information on AIVs in Latin America and highlight the need of more studies on AIVs at the regional level, particularly those focused on identifying the endemic subtypes in regional wild birds.

EDUCAÇÃO AMBIENTAL NO COMBATE AO COMÉRCIO ILEGAL DA AVIFAUNA SILVESTRE EM SERGIPE

<p>Este artigo apresenta os resultados de um projeto de extensão universitária que teve objetivo de conscientizar a população do Estado de Sergipe sobre os impactos negativos do tráfico da avifauna local, que ameaça a sobrevivência das espécies. Foram realizadas palestras em escolas, entrevistas em rádios, distribuições de panfletos e folhetos de cordel em bairros residenciais, escolas e centros comerciais das principais cidades do Estado. A redução na comercialização de aves silvestres em feiras livres, a recusa das lojas agropecuárias em comercializar gaiolas para aves silvestres e a soltura de aves silvestres pelos “criadores de passarinhos” renegados foram alguns dos resultados alcançados neste trabalho.</p>

Response of bird community structure to habitat management in piñon-juniper woodland-sagebrush ecotones

Piñon (Pinus spp.) and juniper (Juniperus spp.) woodlands have been expanding their range across the intermountain western United States into landscapes dominated by sagebrush (Artemisia spp.) shrublands. Management actions using prescribed fire and mechanical cutting to reduce woodland cover and control expansion provided opportunities to understand how environmental structure and changes due to these treatments influence bird communities in piñon-juniper systems. We surveyed 43 species of birds and measured vegetation for 1–3years prior to treatment and 6–7years post-treatment at 13 locations across Oregon, California, Idaho, Nevada, and Utah. We used structural equation modeling to develop and statistically test our conceptual model that the current bird assembly at a site is structured primarily by the previous bird community with additional drivers from current and surrounding habitat conditions as well as external regional bird dynamics. Treatment reduced woodland cover by >5% at 80 of 378 survey sites. However, habitat change achieved by treatment was highly variable because actual disturbance differed widely in extent and intensity. Biological inertia in the bird community was the strongest single driver; 72% of the variation in the bird assemblage was explained by the community that existed seven years earlier. Greater net reduction in woodlands resulted in slight shifts in the bird community to one having ecotone or shrubland affinities. However, the overall influence of woodland changes from treatment were relatively small and were buffered by other extrinsic factors. Regional bird dynamics did not significantly influence the structure of local bird communities at our sites. Our results suggest that bird communities in piñon-juniper woodlands can be highly stable when management treatments are conducted in areas with more advanced woodland development and at the level of disturbance measured in our study.

Blood Parasites of Birds from Almirante, Panama with ecological notes on the hosts

A single-smear survey for blood parasites was conducted among birds of an area with a tropical rain forest climate in Panama. Birds were collected from a variety of habitats including, swamp forests, open fresh water marshes, peridomestic and second growth association and upland tropical rain forests. Smeats from 3,634 birds belonging to 249 species, 48 families and 19 orders were examined and 926, or 25.5%, were found to harbor blood parasites. There were 5 main groups of parasites observed, namely, Plasmodium with 233 positive smears, Haemoproteus with 589, microfilariae with 224, trypanosomes with 61 and Leucocytozoon with 18. Ten different types of Plasmodium were recognized, of these, three did not seem to agree morphologically with any of the described forms of avian piasmodia and were designated in this survey as Butorides, Casmerodius and Piaya types. They were recorded trom the Green Heron, the Common Egret and the Squirrel Cuckoo, respectively. The remaining seven types resembled morphologically the following species : P. relictum, P. cathemerium, P. hexamerium, (= oti), P. nucleophilium, P. vaughani, P. polare, and P. circumflexuz . Twelve distinct types of microfilariae were recognized from 134 smears collected early in the survey. Of these, 2 resembled closely Splendidofilaria wehri Anderson and Pseudaproctella inornata Anderson. Infections of Leucocytozoon were mainly found in North American migrants. There were only 6 smears found positive with this genus of blood parasites from four species of local birds, namely, a heron, a swallow, a flycatcher and an oriole. A list of all avian species collected is presented, giving the scientific and common names of each species. Brief notes on the habits and blood parasites of the species found infected are also included.

Birds and mammals preserved by R. & G. W. Raine Brothers, the Carlisle taxidermists, 1918–1943

An analysis is presented of the material, some 308 items mainly British birds and mammals, submitted for preservation by account holders of R. & G. W. Raine Brothers, taxidermists in Carlisle, between 1918 and 1943. Possible impacts on local bird and mammal populations are discussed.

Excursion – Mullawallah and other local wetlands and Bird List

Excursion – Mullawallah and other local wetlands and Bird List

The local bird trade and its conservation impacts in the city of Guiyang, Southwest China

China has a history and reputation of substantial exploitation of wildlife, and the harvest and trade of wild birds are common throughout the country, both for exportation and local demand. This study documents the diversity and quantity of birds being traded in the city of Guiyang, Southwest China, and evaluates its potential conservation effects. Data were collected through direct observations and through informal conversations on weekends in a public market between March 2014 and February 2015. In total, 206 species belonging to 40 families and 13 orders were recorded, with the family Turdidae having the largest species diversity observed (28 species). The number of individuals on sale was greatly variable among different species. Ashy-throated parrotbills (Paradoxornis alphonsianus) were the most encountered birds, mainly driven by the practice of bird fighting, followed by Acridotheres cristatellus, Garrulax canornus, Zosterops japonicas, Zosterops palpebrosa, Zosterops erythropleurus, Rhyacornis fuliginosus, Emberiza elegans, Leiothrix lutea and Phoenicurus auroreus, which are all common and native to Guiyang. Our data indicated that at least 2000 individuals have been traded in one year for each of these species. We argue that the current bird trade raises a serious potential threat of over-exploitation of these species, especially due to bird fighting and hunting during the breeding season, as well as raising further potential threats of invasive species spread and disease transmission. Measures to control the trade are discussed here, and environmental education could be the most effective. This study highlights the significance of paying more attention to the domestic bird trade in the subtropical region.

Fish, feather, fur and forest: Exploitation of wild animals in medieval Novgorod and its territory

The city of Novgorod the Great in north-west Russia has been subjected to extensive excavation of its superbly preserved medieval anaerobic deposits for many decades. Situated on the River Volkhov near Lake Ilmen and surrounded by mixed boreal and deciduous woodland and seasonally flooded meadowlands, Novgorod was well-placed for the exploitation of local wild fauna and flora. It was also the focus for international trade in furs obtained from a much broader catchment area. Although its inhabitants relied heavily on domestic animals and crops for their food, evidence for the acquisition of wild resources is also provided by animal bones, plant macrofossils, birch-bark documents and other archaeological finds. Pollen analysis has also provided information about landscape history of its hinterland. Even from a limited programme of sieved sampling, it is clear that a very large number of fish bones were present in the deposits. The main taxa are cyprinids, pike and zander, whereas birch-bark documents, largely concerned with tribute, mention salmonids and sturgeon, rare amongst the excavated remains. The wild bird assemblage is dominated by various species of ducks. Other waterfowl were utilised as well as large game birds such as capercaillie. Birds of prey are also present and other remains such as jackdaws reveal the local bird life in town. Wild mammals contributed little to the Novgorodian diet: bones of hare, beaver and elk being the most frequently found. Very few bones of fur-bearing mammals were recovered. The few remains include bear claws and bones of squirrel, marten, otter, and fox, in addition to beaver. Their paucity can be explained by the fact that most would have arrived from the hunting grounds to the north as prepared pelts without bones. Evidence for the hunting for these species is provided on sites deep within the forest zone such as Minino. Most of the wild animals eaten in Novgorod itself were obtained from the land and waters of its near hinterland. The paper discusses the character of the local forest based on pollen and other evidence. Models are being developed to provide a more detailed understanding of the changes in the composition of the forest during the medieval period and the consequences this had for wildlife. The paper demonstrates the benefits of developing a multi-disciplinary approach comparing urban assemblages with contemporary sites in its hinterland and further afield, to understand more fully how wild species were exploited in complex societies.

Avian population trends inScalesiaforest on Floreana Island (2004-2013): Acoustical surveys cannot detect hybrids of Darwin’s tree finchesCamarhynchusspp.

SummaryFloreana Island has the highest proportion of local land bird extinctions on the Galápagos Archipelago, and is home to the range-restricted and critically endangered Medium Tree FinchCamarhynchus pauper. We used acoustic surveys during 2004, 2008 and 2013 to compare the estimated population size ofC. pauperand other land bird species in a remnant patch ofScalesiaforest. First, we compared song inC. pauperandC. parvulusand the recently discoveredCamarhynchushybrid group to justify our use of acoustic surveys to detect population trends given contemporary hybridisation betweenC. pauperandC. parvulus. Song differed significantly betweenC. pauperversusC. parvulusand hybrid birds, but not betweenC. parvulusversus hybrid birds. Second, we compared population size estimates.Camarhynchus pauperdeclined by 52% between 2004 and 2013 (with a 10% increase since 2008);C. parvulus/hybrid increased by 45% between 2004 and 2013 (with 28% decrease since 2008). In 2013, there were ∼ 419C. paupermales in theScalesiaforest (estimate forScalesiahabitat only) and ∼ 2,537 males on Floreana Island (estimate for the entire available highland habitat). Not all species showed a pattern of decline in the highlandScalesiahabitat between 2004 and 2013:Dendroica petechia(+256%),Crotophaga ani(+254%)Geospiza fuliginosa(+23%), andMyiarchus magnirostris(+11%) increased, while the ground finchG. fortis(-76%) decreased. Understanding whyC. pauperis declining while other land bird species are increasing in the same habitat requires continued inquiry and monitoring efforts.

Soil Quality Manipulation to Reduce Bird Presence at Airports

Aviation safety is an important concern in wildlife management as bird strikes risk human lives and result in costly damage. Habitat management can decrease bird abundances locally at airports. We tested soil manipulation as a technique to reduce local bird presence by establishing experimental plots with either intact topsoil or stripped subsoil with the aim of decreasing foraging substrate for birds. We estimated invertebrate abundance, and observed bird presence from 2006 to 2008. More birds visited topsoil plots (151.5 birds/ ha/hour) than subsoil plots (72.7 birds/ha/hour). Topsoil plots supported a greater biomass of invertebrates than subsoil plots ( = 0.39 g/50 cm 3 , 0.21 g/50 cm 3 , respectively). Bird abundance reflected soil variation in invertebrate abundance. Reducing topsoil quality may merit further consideration as a means of reducing local bird activity and abundances at airports.

Denaturing the Korean DMZ

In this essay, I analyze representations of nature in the landscape architecture and architecture of the partially built Migratory Bird Village (MBV) project proposed near the Korean Demilitarized Zone. In an international context of conflicting political and economic agendas, this ecotourism project represents the particular contexts of local human and nonhuman populations. The project embeds within its design drawings, maps, and charts a grounded environmentalism responsive to local farmers, birds, and history. MBV demonstrates how landscape architects and architects can work with communities to value nature as a locally specific cultural and spatial condition. But, like other representation projects addressing biodiversity, this speculative project also demonstrates the perils of greenwashing. Despite the careful particularity of its ecological and social goals, the project replays an international greening style that portrays environmentally destructive development as natural. This formulaic eco-logic readily backfires by supporting associated territorial and capital growth more than the nature it represents. I draw on Jacques Derrida’s deconstructive analysis of nature’s cultural formulation to examine how the idealized representations of ecological design projects can act paradoxically to denature even as they naturalize environments.

Die Brutvogelfauna eines Nadelwaldes der nördlichen Voralpen nach dem Sturm Lothar

Breeding bird fauna in a coniferous forest in the northern Prealps after storm Lothar In a 70-hectare large coniferous forest located on the northern edge of the Alps in central Switzerland, Canton of Obwalden, at an altitude of 1260 to 1550 metres above sea level, we surveyed the local breeding bird fauna in 2002 and 2013 by means of point counts as well as additional area searches for rare species. In December 1999, hurricane Lothar caused two large windthrow areas and several smaller areas with scattered throws in the survey range. We found a total of 48 breeding bird species, which is a very diverse species composition for a mountain forest. In the eleven years between surveys, a decline in distribution or abundance was recorded for four species, while seven species showed an increase; a further four species showed no change. For the remaining species, the data sets were too small to reliably estimate changes. A comparison with forest structure data provided by the Swiss Federal Institute of Forest, Snow and Landscape Research WSL revealed that for five bird species, the changes in distribution or abundance could be explained at least partially by forest succession. In order to obtain realistic distribution and abundance values in this kind of breeding bird survey, it is essential to collect large enough samples and to consider the detection probability of each individual species using appropriate statistical methods.

European Aedes albopictus and Culex pipiens Are Competent Vectors for Japanese Encephalitis Virus.

BackgroundJapanese encephalitis virus (JEV) is the causative agent of Japanese encephalitis, the leading cause of viral encephalitis in Asia. JEV transmission cycle involves mosquitoes and vertebrate hosts. The detection of JEV RNA in a pool of Culex pipiens caught in 2010 in Italy raised the concern of a putative emergence of the virus in Europe. We aimed to study the vector competence of European mosquito populations, such as Cx. pipiens and Aedes albopictus for JEV genotypes 3 and 5.FindingsAfter oral feeding on an infectious blood meal, mosquitoes were dissected at various times post-virus exposure. We found that the peak for JEV infection and transmission was between 11 and 13 days post-virus exposure. We observed a faster dissemination of both JEV genotypes in Ae. albopictus mosquitoes, when compared with Cx. pipiens mosquitoes. We also dissected salivary glands and collected saliva from infected mosquitoes and showed that Ae. albopictus mosquitoes transmitted JEV earlier than Cx. pipiens. The virus collected from Ae. albopictus and Cx. pipiens saliva was competent at causing pathogenesis in a mouse model for JEV infection. Using this model, we found that mosquito saliva or salivary glands did not enhance the severity of the disease.ConclusionsIn this study, we demonstrated that European populations of Ae. albopictus and Cx. pipiens were efficient vectors for JEV transmission. Susceptible vertebrate species that develop high viremia are an obligatory part of the JEV transmission cycle. This study highlights the need to investigate the susceptibility of potential JEV reservoir hosts in Europe, notably amongst swine populations and local water birds.

A Review of Gray Partridge Restocking in the UK and its Implications for the UK Biodiversity Action Plan

The gray partridge Perdix perdix has been the subject of many re-introduction projects throughout the world. In earlier attempts many releases simply aimed to increase the number of individuals for harvesting. This is very different from a conservation project aiming to establish a self-sustaining population. In recent decades, the gray partridge has declined severely in abundance and it is a species of conservation concern throughout Western Europe. Until now, gray partridge releasing projects have mainly focused on releasing large numbers of captive-reared individuals, of which few survive because of heavy predation and low breeding success. We reviewed the scientific and gamekeepering literature, and found that nevertheless a number of traditional methods for rearing and releasing gray partridges exist. Although these have primarily been developed to supplement existing wild stocks to produce shootable resources, some can be re-used today for conservation purposes. The most promising system for producing birds for re-introduction and supplementation purposes is to obtain eggs from a reliable source, hatch and rear the chicks under bantams to eight weeks of age, then foster to failed pairs of wild gray partridges. A less labour-intensive alternative is to hatch and raise chicks under artificial heat and foster these to unsuccessful wild pairs. Obviously these two systems are dependent on the presence of local free-living wild birds. If no pairs of wild gray partridges are present it is necessary to establish a founder population first. We see two methods to achieve this goal, the release of coveys in autumn or of pairs in spring. An important pre-requisite to any restocking scheme is appropriate management including the provision of suitable habitat for feeding and nesting and the control of predators, otherwise restocking is unlikely to lead to long-term establishment.

Conservation of breeding grassland birds requires local management strategies when hay maturation and nutritional quality differ among regions

Early hay harvest can negatively affect grassland bird reproduction. Agriculturists may delay harvest in support of grassland bird conservation if hay quality is not jeopardized. We examined changes in hay quality over time at three latitudes in Ontario, and for the central region, we related results to bobolink (Dolichonyx oryzivorus) breeding phenology. We collected hay samples at all latitudes from 1 June through 16 July and quantified changes in percent crude protein (CP), acid detergent fibre (ADF), calcium (Ca) and phosphorus (P). At the same time, we also monitored breeding behaviour of all grassland birds but sufficient data for analyses and comparative purposes were collected only for bobolinks in central Ontario. Most Ontario hayfields sampled were low in energy and digestibility throughout the growing season (mean ADF values>35%). Ca levels were more than adequate for most livestock but P supplementation may be required depending on the production goals of the farmer. Crude protein levels were higher in forage samples collected from northern study plots and fell below 10% one week later than in central and southern Ontario. In central Ontario, CP levels were highest in the first week of June (12–15%). In the last two weeks of June through to mid-July, mean CP levels dropped from 11% to 9.5%, roughly 0.5% per week. Fledgling bobolinks were first observed on 14 and 16 June; they were counted in larger numbers after 20 June and reached a peak 1–14 July. A delayed hay harvest (mid-July) in this region would support bobolink reproduction without compromising forage quality for a variety of livestock enterprises. Timing of hay harvest to benefit grassland birds in regions to the north and south may differ depending on local geologic and climatic conditions and breeding bird behaviour. Based on our results, farmers that opt to manage their hayfields in support of grassland birds can delay the timing of hay harvest with trade-offs not as severe as once thought. The delayed hay harvest strategy may have wider applications to agro-ecosystems globally; its feasibility would only require knowledge of local breeding bird activity and forage quality over time.

Prey or play: interactions between walruses and seabirds

Several anecdotal reports indicate that walruses (Odobenus rosmarus) occasionally attack seabirds, which potentially impacts local bird populations. However, the manner in which walruses interact with seabirds and the motivational basis of such interactions have not been investigated. Here, we describe and characterize the behaviour of wild Pacific walruses (O. r. divergens) directed at seabirds in water near the summer haulout in the Chukchi Sea. Although most walruses showed no interest in seabirds nearby, some individuals intentionally approached them both alone and in groups. A total of 74 seabird encounters for 71 individually identified walruses were registered. Behavioural analysis based on detailed observations, photography and video recording showed that the most common types of walrus behaviour toward a bird were approach by surfacing and splash, approach by surfacing and hit and attack from below. Immature individuals initiated 82% of encounters. The motivation to approach a bird was low in adult individuals, with the majority of encounters involving adults initiated by males. Walrus encounters with live birds showed a very low rate of bird kill. Encounters with dead birds were followed by further manipulations with bird carcasses, which included both the consumption of bird soft tissue and object play taking the form of drop–catch behaviour. In addition eight cases of the object-oriented play with a bird carcass in a group of walruses were observed. Object play in wild walruses is reported for the first time. Our results indicate that in seabird encounters, walruses display diverse behavioural patterns, not limited to predatory responses.