Food of the rook (Corvus frugilegus L.) in Hawke's Bay,New Zealand

Abstract

Throughout a year gizzards from 160 adult and juvenile rooks and 105 large young in rookeries were collected from Hawke's Bay. The main foods were invertebrates (especially Diptera larvae and Coleoptera adults) during the warmer months and walnuts and acorns in autumn and winter. When these foods were scarce cereals were taken, mainly from stubble. Other important food items were carrion, earthworms, peas, grass, and clover. Foods fed to young rooks were similar to those eaten by adults except that the young were fed more striped dung fly (Hybopygia varia) larvae (P < 0.025) and fewer blow fly (Calliphoridae) larvae (P < 0.025).     

BODY MEASUREMENTS,PLUMAGE AND MOULT OF THE SACRED IBIS IN SOUTH AFRICA

Lowe, K. W., Clark, A. & Clark, R. A. 1985. Body measurements, plumage and moult of the Sacred Ibis in South Africa. Ostrich 56: 111–116.

Body measurements, plumage and moult of Sacred Ibis Threskiomas aethiopicus were studied at Pretoria from July 1973 to June 1974. Adult and immature Sacred Ibises are sexually dimorphic in size. Bill length alone can be used to sex most birds. Body mass, wing, tarsus and tail lengths overlap greatly between the sexes but males are generally larger than females. The sexes show similar patterns of variation in body mass and gonad size throughout the year. Juveniles follow a different pattern of variation in these parameters. The plumages of adults, immatures and juveniles are described and compared. There is no sexual dimorphism in plumage pattersn. Moult in adults occurs mainly in the post-breeding period from January to August, and in juveniles and immatures throughout the year. Adult Sacred Ibises have an-extensive, irregular and asymmetrical moult. Factors affecting sexual size dimorphism in African and Australian populations are discussed.     

OBSERVATIONS ON THE BREEDING OF THE GREATER FLAMINGO PHOENICOPTERUS RUBER LINNAEUS IN THE BREDASDORP DISTRICT,SOUTH AFRICA

Clark, R. A. 1979. Seasonal levels of body fat, protein, ash and moisture in the Sacred Ibis. Ostrich 50:129-133.

Sacred Ibises Threskiornis aethiopicus in Pretoria, Transvaal, were analyzed for body composition throughout the year. Body fat levels in adults and immatures were approximately 7% of feather-free empty body mass in the winter. Just prior to breeding the levels of fat were approximately 12% in adults and 6% in immatures. Lowest levels were recorded for adults and immatures in January (3,5%). In contrast to fat, levels of moisture, protein and ash did not appear to vary significantly between seasons.     

NOTES ON THE CAPRIMULGIDAE OF THE KAFUE BASIN

During 2002–2007, we assessed the status of the Purple Heron Ardea purpurea in Numidia, Algeria by surveying all the major wetlands in the region. We located six distinct breeding sites; four of these were not previously known. We also investigated nest site selection and determined the species’ reproductive success at Dakhla, a dunary pond during two successive years (2006 and 2007). The egg laying period was comparable to that reported for southern Europe (March-May) and a seasonal change of breeding success was recorded. A growth curve was derived for developing nestlings and the impact of an ectoparasite (mite) infestation upon nestling's growth was considered. We also examined 73 food boluses regurgitated by nestlings and identified 329 prey items. Fish, mainly Gambusia holbrookii and Cyprinus carpio, dominated by mass, whereas insects, mainly aquatic Coleopteran larvae and aeshnids (Odonata), were the most frequent prey (67.1%). Loss of habitat is identified as a major threat to the future of colonial herons in Algeria.     

Diet of the black-headed heron Ardea melanocephala during the breeding season in South African grasslands

The diet of the black-headed heron was studied using analysis of pellets and prey remnants (225 prey items identified) collected from four sites in South African Highveld Grassland, transformed into cultivated fields. Small vertebrates comprised the staple food of chicks. Rodents were the most important vertebrate prey. Otomys irroratus comprised ca. 50% of the total biomass of vertebrate prey consumed. The diet was supplemented by small lizards, snakes, frogs and fishes. Grasshoppers, beetles, crabs and other arthropods were occasionally preyed upon.     

Diets of adult and nestling starlings (Sturnus vulgaris) in Hawke’s Bay,New Zealand

Abstract

Gizzards were examined from 334 adult and 62 nestling starlings collected in mixed farmland during 1971–72. The birds ate insects, spiders, earthworms, snails, millipedes, centipedes, seeds, and fruits. Starlings ate fewer subterranean animals (7%) than those usually living partially hidden (45%), on the ground (31%), or on vegetation (18%). About half the invertebrates eaten were 2–5 mm long and about a quarter 6–10 mm long. Nestlings tend to be fed significantly larger items than were eaten by adults. The commonest items in adult starlings were Coleoptera adults, Lepidoptera larvae, Hemiptera, and fruits; in nestlings, Coleoptera adults and Diptera adults and larvae were important. Earthworms were found in all the nestlings. More than 50% of adult gizzards contained earthworm chaetae in wetter months, but fewer in drier months. The diet of starlings, despite considerable overlap with the foods eaten by mynas, rooks, and magpies, included somewhat different components and proportions of the food supply. Fruits were found in adults only; most were probably eaten after harvest. Although predation on two major pasture pests—Costelytra zealandica and Wiseana cervinata larvae—was insubstantial, nearly 40% of the total invertebrates eaten by adult starlings were insect pest species.     

Philornis infection in blue‐black grassquits: impact on nestlings and risk factors involved

Parasitic botfly larvae (Philornis ssp., Diptera: Muscidae) are found in nests of several bird taxa, although prevalence and impact on nestling survival vary considerably among species. Here we describe patterns of botfly infestation in blue‐black grassquit Volatinia jacarina nestlings. We identified the most typically affected nestling body parts and assessed parasite prevalence, impact on nestling survival, and changes in nestling body shape. Additionally, we tested whether climatic conditions, nest morphology and habitat characteristics are associated with larvae abundance. Blue‐black grassquits had low breeding success (16% of eggs/nestlings survived to fledged; 19% of the nests fledged at least one), but most failures resulted from predation by vertebrate predators. We estimated that 1% of nestlings died due to botfly infestation, and the number of subcutaneous larvae (range 1–18) in a nestling's body did not predict fledging success. Infected chicks exhibited higher tarsus asymmetry. Thus, we argue that although botflies had a small impact on offspring survival, they may reduce fitness in adulthood. There was no evidence that environmental conditions and nest morphology are linked to the number of larvae on nestlings. Nesting areas with higher food supply had lower infestation rates. Possibly, food‐rich habitats allow parents to invest more time in offspring care (brooding nestlings), thus protecting them from fly attacks. Alternatively, vegetation composition could influence local invertebrate diversity, which could provide a natural trophic buffer against adult Philornis. The present study brings to light new perspectives concerning bird–botfly interaction.     

Feeding habits of ocellate spot skate,Okamejei kenojei (Müller & Henle, 1841), in coastal waters of Taean,Korea

The feeding habits of Okamejei kenojei were studied using 592 specimens collected in the coastal waters of Taean, Korea from April 2008 to March 2009. O. kenojei is a bottom‐feeding carnivore that consumes mainly shrimp, fishes, and crabs. Its diet also includes small quantities of amphipods, mysids, cephalopods, euphausiids, copepods, isopods, and polychaetes. The total length (TL) of individuals in this study ranged from 8.2 to 49.0 cm. Cluster analysis based on %IRI (index of relative importance) identified three size classes. Group A (< 20 cm TL) ate primarily caridean shrimp and amphipods; group B (20–30 cm TL) ate exclusively shrimp; and group C (> 30 cm TL) ate penaeoidean shrimp, fishes, and crabs. O. kenojei showed ontogenetic changes in feeding habits. Although shrimps were the primary food consumed by all size groups, the proportion of shrimp in the total diet decreased and the consumption of fishes and crabs gradually increased with the body size of O. kenojei. Size of the prey organisms also increased. Smaller individuals fed mainly on small prey, such as amphipods, mysids, and small shrimp, whereas larger individuals preferred larger prey, such as larger shrimp, fishes, and crabs. The size‐related diet breadth and the percentage of empty stomachs were significant; the diet breadth gradually increased with body size, whereas the percentage of empty stomachs decreased. Seasonal changes in the O. kenojei diet were not significant, but shrimp constituted 97.3% of the summer diet by %IRI. Seasonal changes in diet breadth and the percentage of empty stomachs were not significant.     

MINUTES OF THE ANNUAL GENERAL MEETING OF THE SOUTH AFRICA ORNITHOLOGICAL SOCIETY,HELD IN DURBAN ON 11th May 1968

Raseroka, B. H. 1975. Breeding of the Hadedah Ibis. Ostrich 46:208-212.

The Hadedah Ibis Lostrychia hagedash is a common species in the Eastern Cape Province. Nest construction and nesting are described. Normally three eggs are laid, but survival of the nestlings until they can leave the nest is low.     

Summer food of the golden plover Pluvialis apricaria at Hardangervidda, southern Norway

Golden plover stomachs were examined through the breeding season al Hardangervidda, southern Norway. The main foods were Diptera larvae (in particular Tipula excisa ), adult Coleoptera (notably Otiorrhynchus dubius and Carabidae), and in May and August berries of Empetrum hermaphroditum. Also some larvae of Coleoptera and Lepidoptera were taken. Adult Coleoptera were considerably more common in the diet than expected from abundance data, while Araneae were unimportant as food in spite of a high abundance. The males take the major parental duties after hatching, allowing the females a more undisturbed feeding, supposed to be strongly advantageous for them due to close proximity of egg-laying and the start of the postnuptial moult. This is reflected in the diet: in July males showed a larger tropic diversity, and ate more adult insects and less insect larvae than the females.     

Is the Sacred ibis a real threat to biodiversity? Long-term study of its diet in non-native areas compared to native areas

This paper presents the results of a 14-year study about the diet of the Sacred ibis in its main introduction area in France and its impact on native bird species, and compares the data to literature from its native area. During an initial period (1993–2004), the diet was essentially composed of invertebrates such as common aquatic insects (correlated with flooding) or Eristalis larvae picked from the mud (a vacant food niche in France), while scraps of meat taken from rubbish dumps were minor. These traditional preys taken from the same ecosystems as in its native area did not result in an exponential increase of the number of breeding Sacred ibises. Invasive Red swamp crayfish recently replaced other foods in its diet with a resulting sharp increase in breeding pair numbers (R² = 0.48). As in other parts of the world, vertebrates constituted very accidental preys, and no bird species were really threatened by such predation. Conversely, the Sacred ibis can have a positive effect as a predator of invasive crayfish. Adding the species to the DAISIE list of the 100 most invasive alien species in Europe therefore appears debatable.     

A comparison of three methods to investigate the diet of breeding double-crested cormorants (Phalacrocorax auritus) in the Beaver Archipelago, northern Lake Michigan

In order to understand the role of waterbirds in aquatic food webs it is important to first get an accurate depiction of their diet. Three methods of dietary assessment (pellets, regurgitate and stomach contents) are compared here for breeding double-crested cormorants (Phalacrocorax auritus) of the Beaver Archipelago, northern Lake Michigan. By numerical frequency (percent number), each method yielded different depictions of the diet. However, in terms of presence and absence (percent frequency) of possible prey types, stomach content data did agree with both pellets and regurgitate data. However, differences were noted between regurgitate and pellets. In terms of biomass measured (percent biomass) in regurgitate and stomachs, data gathered agreed. In essence, pellets underestimate the importance of alewife (Alosa pseudoharengus) and overestimate the importance of crayfish (Orconectes sp.) in the diet when compared to both regurgitate and stomach analysis. The non-lethal method of regurgitate collection and analysis appears most practical in assessing cormorant diet in this system. In combination with information on avian foraging ecology and prey populations, these data may be used to investigate the relationships among cormorants and their prey, and lead to a better understanding of Great Lake food web dynamics.     

Storing prey in larders affects nestling haematological condition in the Red-backed Shrike (Lanius collurio)

Many animals, including shrikes (Laniidae), are known to store food. This behaviour ensures food availability during inclement weather, for rearing nestlings or signalling territory quality. Unlike most other shrike species, which accumulate food before breeding, Red-backed Shrikes Lanius collurio store food in larders, mainly during the nestling and fledgling periods. If this is an adaptive behaviour, variation in this behaviour should affect either or both the number and condition of nestlings, which may benefit from such larders. We assessed the haematological condition of Red-backed Shrike nestlings in east-central Poland in 2021 using a suite of blood parameters relating to sites where shrikes did or did not store food. Haemoglobin concentrations were positively correlated with larders, being significantly higher in nestlings of pairs that stored prey compared with those whose parents did not do so. White blood cell counts were lower in nestlings whose parents kept larders. Red blood cell counts and glucose concentrations in nestlings were not related to whether parents had larders. Food storage probably ensures a more constant access to food, which results in a superior haematological condition in nestlings.     

THE BIRDS OF LIVINGSTONE TOWNSHIP,NORTHERN RHODESIA, 1942–1950

Summary

Clark, R. A. 1979. DDT contamination of the Sacred Ibis. Ostrich 50:134-138.

Samples of fat and brain from Sacred Ibises Threskiornis aethiopicus in Pretoria, Transvaal, were analyzed for organochlorine insecticides. Except for traces of p,p'-DDT only p,p'-DDE was found to occur (means of 28,35 mg/kg wet fat and 0,22 mg/kg wet brain). There was a significant correlation between the concentrations of DDE in the fat and brain of birds (r = 0,53; p ? 0,01). In the period when Sacred Ibises mobilized their fat reserves there was no significant correlation between the level of body fat and the concentration of DDE in either the brain or the remaining body fat.     

Trophic and Spatial Niches of two Large-sized Species of Leptodactylus (Anura) in Southeastern Brazil

Leptodactylus ocellatus (LO) and L. labyrinthicus (LL) are known to prey on other frogs. Here we compare their food habits based on the analysis of stomach contents and their spatial distribution when in sympatry. LO was found most frequently near stream banks, and LL on the margins of lakes and ponds. LO was found within 10 m of permanent water bodies; LL frequently used ponds far from lakes and rivers. Coleoptera, Formicidae, and Isoptera comprised 52% of the prey types identified in the LO sample, whereas Coleoptera and insect larvae represented 58% of the prey items of LL. Frogs were not frequent in the diet of either species but, in volume, represented the second most important category for LO and the first for LL. LO showed a larger trophic niche breadth than LL. The trophic niche overlap between the two species was 68.3% for percentage of prey items. The present work confirms the relative importance of frogs in the diet of both species. The greater capacity of LL in moving far away from permanent water bodies may generate better opportunities for prey selection and a narrower trophic niche breadth. The large range of prey used by these two species indicates they are generalist/opportunistic feeders.     

Temporal changes in food resources,parental feeding and breeding success of Heron Island silvereyes,Zosterops lateralis chlorocephala

The influences of the temporal change in food supply on the parental feeding effort and breeding success of silvereyes,Zosterops lateralis chlorocephala, was investigated on Heron Island, Australia. Food supply (arthropods and figs) declined as the breeding season progressed. The parental feeding rate and growth of nestlings were lower when food supply was poor. When available, dominant pairs fed their young more figs and fewer arthropods than lower ranking pairs. Dominant pairs raised heavier young than lower ranking pairs when food supply was poor, while there were no significant differences between them when food supply was rich. When food supply was rich, pairs delivering greater amounts of arthropods reared nestlings better, whereas feeding more figs did not improve growth of nestlings. When food supply was poor, pairs spending a longer time at the nest reared nestlings better.     

Effects of superabundant food on breeding success and behavior of the red-winged blackbird

Summary The effects of food on breeding success and behavior of the red-winged blackbird (Icteridae: Agelaius phoeniceus) were investigated during 3 successive breeding seasons. In the second season, a 4-week pulse of abundant food in the form of a periodical cicada emergence (Homoptera: Cicadidae: Magicicada spp.) occurred in the forest adjacent to the marsh where the birds were breeding.During the cicada period, the bird population showed: 1) an increase in foraging trips to the forest and a decrease in trips per h, 2) increased biomass of nestlings, 3) increased nestling survival caused by decreased starvation, 4) increased fledging success, and 5) bimodal weight distributions of older nestlings (reflective of the sexual dimorphism in this species). These data suggest the temporary removal of food limitations on the breeding population when the pulse of food was available.     

Differential Begging and Locomotory Behaviour by Early and Late Hatched Nestlings Affecting the Distribution of Food in Asynchronously Hatched Broods of Altricial Birds

Distribution of food to early and late hatched nestlings was studied in asynchronously hatched broods of the great tit Parus major, the blackbird Turdus merula, and the fieldfare T. pilaris. Food distribution is related to the locomotory and begging behaviour and positions in the nest of these nestlings. Late hatched (small) nestlings were found to beg more often per feed than bigger nestlings and move more towards favoured positions in the nest to counteract selective feeding of bigger young. The functional significance of these differences in the behaviour of early and late hatched nestlings are discussed. It is argued that they are adaptive by 1) ensuring that each nestling survives when food supplies are ample, and 2) by mediating an optimal brood reduction when food is insufficient to raise the entire brood. The roles of asynchronous hatching, and selective feeding which follows from differential behaviour of early and late hatched young are discussed in relation to food conditions during the breeding season.     

Temporal variations in the diet of brown trout (Salmo trutta L.) and rainbow trout (S. gairdneri R.) in Rutland Water

The diet of brown trout (Salmo trutta L.) and rainbow trout (S. gairdneri Richardson) in Rutland Water were compared during the first two fishing seasons (April–October 1977 and 1978).Fortnightly samples of approximately forty stomachs were obtained from boat and bank, rod-and-line caught trout giving a total of 1046 stomachs over the two seasons.During 1977 seasonal changes in the diet were divided into two phases; the first being a period of abundant drowned terrestrial food until June. This was followed by a period of more stable water level from July onwards when chironomid larvae and pupae were consistently the most important food items and the diversity of food also increased.In 1978 the proportion of chironomid pupae and larvae declined and they were replaced in the diet by Gammarus and Asellus.     

Quantitative relationships between the numbers of fecal pellets, fecal weights and the weight of food eaten by tobacco hornworms,Protoparce sexta (Johan.) (Lepidoptera: Sphingidae)

Thenumber of fecal pellets was found to be an unreliable index of food consumption. There is, however, a high correlation between the weight eaten and the weight excreted. Nevertheless, caution must be exercised in using this relationship to compare consumption by different groups of larvae since the weight consumed per mg excreted varies with the quality of the food, the age and physiological state of the larvae and various environmental factors.

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Quantitative beziehungen zwischen kotballenzählungen, kotgewichten und dem gewicht der von tabakschwärmer-raupen,Protoparce sexta (Johan.) (Lepidoptera: Sphingidae), aufgenommenen nahrung

Zusammenfassung Die Verwendbarkeit von Kotballenzählungen und Kotgewichten als Maßstab für die vonProtoparce sexta-Raupen aufgenommene Nahrungsmenge wird kritisch untersucht. Es zeigt sich, daß die Anzahl der Kotballen kein verbindliches Maß für den Nahrungsgebrauch darstellt. Dagegen besteht eine konstant hohe Korrelation zwischen dem Trockengewicht der aufgenommenen Nahrung und dem Trockengewicht des Kotes. Jedoch darf beim Vergleich des Nahrungsverbrauchs verschiedener Gruppen von Raupen diese Beziehung nur mit Vorsicht benutzt werden, da das Verhältnis von verbrauchtem zu ausgeschiedenem Gewicht (der Nahrung bzw. des Kotes) mit der Nahrungsqualität, dem Alter und dem physiologischen Zustand der Raupen und mit den Umweltbedingungen variiert.