scholarly journals Causes of land-bird extinctions in French Polynesia

Oryx ◽  
1992 ◽  
Vol 26 (4) ◽  
pp. 215-222 ◽  
Author(s):  
Roland ◽  
Julia Seitre
Keyword(s):  
Rattus Rattus ◽  
Bird Species ◽  
French Polynesia ◽  
Habitat Destruction ◽  
Population Declines ◽  
Ecological Data ◽  
Rapid Action ◽  
Introduced Predators ◽  
Land Bird

During a 4-month study in French Polynesia, the authors visited 28 islands, seven of which had never been explored by ornithologists. They collected ecological data on endemic land birds, introduced animals and habitats, focusing particularly on the factors involved in population declines and extinctions. As well as hunting and habitat destruction, it appears that introduced predators play a major role, with the roof rat Rattus rattus being the most dangerous. Rapid action to eradicate introduced predators, coupled with translocations, would be the most effective way to ensure the survival of the remaining bird species.

scholarly journals Factors affecting the distribution of landbirds on the Falkland Islands

2001 ◽  
Vol 12 (2) ◽  
pp. 151-167 ◽  
Author(s):  
James R. Hall ◽  
Robin W. Woods ◽  
M. de L. Brooke ◽  
Geoff M. Hilton
Keyword(s):  
Conservation Status ◽  
Bird Species ◽  
Habitat Destruction ◽  
Habitat Modification ◽  
Conservation Action ◽  
Factors Affecting ◽  
Island Species ◽  
Introduced Predators ◽  
Isolation Effects ◽  
Bird Distribution

A high proportion of island birds are threatened with extinction as a result of their vulnerability to introduced predators, habitat destruction, and fragmentation/isolation effects. In order to conserve island species effectively, it is necessary to disentangle these effects on distribution and abundance. We attempt to do this for the nine native passerines in the Falkland (Malvinas) Islands, using a database of presence/absence on 59 offshore islands in the archipelago, linked to data for each island on mammal presence, habitat modification, and isolation. Falklands native passerines are of considerable conservation importance, comprising one endemic globally threatened species, several endemic subspecies, and several restricted range species. Presence of rats on islands was by far the most important predictor of passerine presence, overriding the effect of habitat modifications. The globally threatened endemic Cobb's Wren Troglodytes cobbi was absent from all islands containing rats. Some species were more likely, and others less likely to occur on islands where tussac Poa flabellata grassland had been destroyed by grazing. The former species were primarily those adapted to dwarf-heath vegetation, and/or that thrive around human settlements. Island size and isolation were important predictors of occurrence for several bird species. The analyses show that, if vegetation restoration in the Falklands is to meet conservation aims, then it should be accompanied by introduced mammal control. Secondly, they indicate that biogeographical effects on bird distribution among islands in the Falklands are important, and need to be considered when assessing the conservation status of species, and when considering conservation action.

scholarly journals Stuck amongst introduced species: Trophic ecology reveals complex relationships between the critically endangered Niau kingfisher and introduced predators, competitors and prey

NeoBiota ◽  
2019 ◽  
Vol 53 ◽  
pp. 61-82
Author(s):  
Diane Zarzoso-Lacoste ◽  
Elsa Bonnaud ◽  
Emmanuel Corse ◽  
Vincent Dubut ◽  
Olivier Lorvelec ◽  
...  
Keyword(s):  
Trophic Interactions ◽  
Trophic Ecology ◽  
Prey Availability ◽  
Rattus Rattus ◽  
Food Resource ◽  
Bird Species ◽  
Critically Endangered ◽  
Exploitative Competition ◽  
Predator Species ◽  
Introduced Predators

The introduction of mammals on oceanic islands currently threatens or has caused the extinction of many endemic species. Cats and rats represent the major threat for 40 % of currently endangered island bird species. Direct (predation) and/or indirect (exploitative competition for food resource) trophic interactions are key mechanisms by which invaders cause the decrease or extinction of native populations. Here, we investigated both direct and indirect trophic interactions amongst four predator species (i.e. animals that hunt, kill and feed on other animals), including three introduced mammals (Felis silvestris catus, Rattus rattus and Rattus exulans) and one critically endangered native bird, the Niau kingfisher (Todiramphus gertrudae). All four species’ diets and prey availability were assessed from sampling at the six main kingfisher habitats on Niau Island during the breeding season. Diet analyses were conducted on 578 cat scats, 295 rat digestive tracts (218 R. exulans and 77 R. rattus) and 186 kingfisher pellets. Despite simultaneous use of morphological and PCR-based methods, no bird remains in cat and rat diet samples could be assigned to the Niau kingfisher, weakening the hypothesis of current intense predation pressure. However, we determined that Niau kingfishers mainly feed on introduced and/or cryptogenic prey and highlighted the potential for exploitative competition between this bird and both introduced rat species (for Dictyoptera, Coleoptera and Scincidae). We recommend removing the cats and both rat species, at least within kingfisher breeding and foraging areas (e.g. mechanical or chemical control, cat sterilisation, biosecurity reinforcement), to simultaneously decrease predation risk, increase key prey availability and boost kingfisher population dynamics.

Detecting predation of a burrow-nesting seabird by two introduced predators, using stable isotopes, dietary analysis and experimental removals

2007 ◽  
Vol 34 (6) ◽  
pp. 443 ◽  
Author(s):  
Grant A. Harper
Keyword(s):  
Rattus Rattus ◽  
Isotopic Analysis ◽  
Diet Analysis ◽  
Passerine Birds ◽  
Dietary Analysis ◽  
Stable Isotopic Analysis ◽  
Introduced Predators ◽  
Ship Rat ◽  
Stable Isotopic ◽  
Burrowing Seabirds

Burrowing seabirds are vulnerable to extirpation by introduced predators such as rats, but much evidence of predation is circumstantial. On Taukihepa, an island off southern New Zealand, two possible predators exist with sooty shearwaters (Puffinus griseus): the weka (Gallirallus australis), a large rail, and the ship rat (Rattus rattus), both introduced to the island. It was expected that chick predation would be principally by weka, the much larger of the two predators. To measure losses of sooty shearwater chicks to weka or rats, nests were monitored with burrow-scopes at six sites in the summers of 2003–04 and 2004–05. In three of the sites rats were removed on 4-ha grids by trapping. In the other three sites rats were not trapped. In addition, weka were removed from all six sites in 2005. Concurrent diet analysis of weka and rat stomachs was undertaken as well as stable isotopic analysis (δ13C, δ15N) of samples from rats and weka. These were compared with possible prey items including sooty shearwaters. Additional stable isotope samples were taken from Pacific rats (Rattus exulans), a small rat species present with weka and sooty shearwaters on nearby Moginui Island. Weka diet comprised ~40% of bird remains by volume and calculations using Isosource, an isotopic source portioning model, estimated sooty shearwaters contributed 59% (range: 15–71%) of weka diet during the sooty shearwater chick-raising period. Ship rats, in contrast, had very depleted δ13C isotope signatures compared with sooty shearwaters and bird remains contributed <9% of diet by volume, with Isosource calculations suggesting that ship rats consumed more passerine birds (mean: 30%; range 5–51%) than sooty shearwaters (mean 24%; range: 0–44%). In both summers, more chicks were lost on sites from which rats had been removed than on control sites. When weka were removed in 2005, fewer chicks were lost than in 2004 and significantly fewer weka-killed chicks were found on weka-removal sites than on non-removal sites. Weka were the principal predator of sooty shearwater chicks, depredating an estimated 9.9% of nests. Combining several techniques quantified the loss and identified the principal predator of a seabird in decline.

Vagrants and the Paucity of Land Bird Species at the Prince Edward Islands

1980 ◽  
Vol 7 (3) ◽  
pp. 305 ◽  
Author(s):  
A. E. Burger ◽  
A. J. Williams ◽  
J. C. Sinclair
Keyword(s):  
Bird Species ◽  
Prince Edward Islands ◽  
Land Bird

scholarly journals Hunting of migratory birds in North Sinai, Egypt

2015 ◽  
Vol 26 (1) ◽  
pp. 39-51 ◽  
Author(s):  
PERRI EASON ◽  
BASEM RABIA ◽  
OMAR ATTUM
Keyword(s):  
Migratory Birds ◽  
Bird Species ◽  
Migratory Bird ◽  
Mediterranean Coast ◽  
Population Declines ◽  
Mp3 Players ◽  
Southern Mediterranean ◽  
Sand Bar ◽  
North Sinai ◽  
Desert Scrub

SummaryDuring autumn migration, people set trammel nets along most of the Mediterranean coast of Egypt, with migrating Common Quail Coturnix coturnix as their primary target. These nets capture large numbers of quail, but also illegally capture other birds, which are then killed. We present the results of surveys from 2008 to 2012 along these lines of nets on the coast of North Sinai, Egypt. In desert scrub, which covers most of the Sinai coast, the mean number of quail killed reached a high of 357.1 per km per day in 2012, with a grand mean over the study period of 191.9 per km per day. Trammel nets also captured 54 other bird species in 28 families. Species captured at the highest rates in desert scrub included Corncrake Crex crex, Isabelline Wheatear Oenanthe isabellina and Greater Short-toed Lark Calandrella brachydactyla. Based on mean rates of capture from 2008 to 2012 in desert scrub and sand bar habitats, we estimate 2.0 million quail and 0.5 million birds of other species are killed annually in North Sinai during the 45 days of peak migration. In 2012, however, after the use of MP3 players to attract quail became widespread, we estimate that 3.3 million quail and 0.5 million other birds were captured. Hunters near the coast have recently begun covering shrubs and trees with mist nets to catch passerines. From 2010 to 2012, mist nets along our survey routes caught birds of 17 species in three families, with seven of these species caught only in this type of net. Hunting is likely to be a contributing factor to population declines for some species that migrate across Egypt and further studies of migratory bird hunting along the southern Mediterranean shore are badly needed.

Introduced predators and cavity-nesting seabirds: unexpected low level of interaction at breeding sites

2008 ◽  
Vol 86 (9) ◽  
pp. 1068-1073 ◽  
Author(s):  
L. Ruffino ◽  
K. Bourgeois ◽  
E. Vidal ◽  
J. Icard ◽  
F. Torre ◽  
...  
Keyword(s):  
Rattus Rattus ◽  
Breeding Cycle ◽  
Mediterranean Islands ◽  
Breeding Sites ◽  
Low Level ◽  
Black Rat ◽  
Cavity Nesting ◽  
Introduced Predators ◽  
Puffinus Yelkouan ◽  
First Time

The mechanisms by which introduced predators and long-lived seabirds interact and even coexist are still poorly known. Here, the interactions between the widely introduced black rat ( Rattus rattus (L., 1758)) and an endemic Mediterranean cavity-nesting seabird, the yelkouan shearwater ( Puffinus yelkouan (Acerbi, 1827)), were for the first time investigated for a set of 60 suitable breeding cavities throughout the entire breeding cycle of this seabird. Our results pointed out that rat visits to cavities were significantly higher when shearwaters had left the colony for their interbreeding exodus. Among the set of suitable breeding cavities, yelkouan shearwaters preferentially selected the deepest and the most winding cavities for breeding. Very few rat visits were recorded at the shearwater-occupied cavities and no predation event was recorded. These intriguing results reveal a low level of interaction between introduced black rats and yelkouan shearwaters, which may have facilitated their long-term coexistence for thousands of years on some Mediterranean islands.

scholarly journals An Assessment on Bird’s Diversity in Bagmati River Corridor

1970 ◽  
Vol 2 (1) ◽  
pp. 34-40
Author(s):  
Saroj Thapa ◽  
Shambhu Paudel ◽  
Dipak BK
Keyword(s):  
Public Perception ◽  
Habitat Degradation ◽  
Bird Species ◽  
Habitat Destruction ◽  
Conservation Area ◽  
Point Count ◽  
The Public ◽  
One Year ◽  
Bagmati River ◽  
River Corridor

Bagmati River is considered as a potential conservation area in terms of the bio-diversity conservation due to its unique and diversified habitat distribution. Due to various causes, the river is being polluted and hence habitat degradation rate is increasing. As a consequence, the direct effect is seen on birds inhabiting there. Aiming the assessment of bird's diversity, one year survey was conducted in Bagmati River from Tilganga Bridge to chobhar Gorge Bridge (here after termed as Bagmati river corridor) by applying the point count method .In the total enumeration, 100 of birds species were recorded among which 7 are listed in CITES appendix. The bird species that are regarded as globally threatened are not recorded in the study area. In this report, some potential patches in the study area, are described as hot spots, considering the higher probability of recording maximum number of birds species. The public voice is also collected to find out the public perception on the present status of birds of Bagmati river corridor using the questionaire method. Some causes of habitat destruction and some potential conservation measures are also mentioned. Key Words: Bagmati river corridor, Birds, Conservation, Hotspots, Diversity, Habitat   DOI: 10.3126/init.v2i1.2520 The Initiation Vol.2(1) 2008 pp34-40

scholarly journals Are declines in insects and insectivorous birds related?

The Condor ◽  
2021 ◽  
Author(s):  
Douglas W Tallamy ◽  
W Gregory Shriver
Keyword(s):  
Plant Species ◽  
Invasive Plant ◽  
Bird Species ◽  
Insect Herbivores ◽  
Native Plant ◽  
Insectivorous Birds ◽  
Population Declines ◽  
Native Plant Species ◽  
Host Plant Specialization ◽  
Scale Population

Abstract A flurry of recently published studies indicates that both insects and birds have experienced wide-scale population declines in the last several decades. Curiously, whether insect and bird declines are causally linked has received little empirical attention. Here, we hypothesize that insect declines are an important factor contributing to the decline of insectivorous birds. We further suggest that insect populations essential to insectivorous birds decline whenever non-native lumber, ornamental, or invasive plant species replace native plant communities. We support our hypothesis by reviewing studies that show (1) due to host plant specialization, insect herbivores typically do poorly on non-native plants; (2) birds are often food limited; (3) populations of insectivorous bird species fluctuate with the supply of essential insect prey; (4) not all arthropod prey support bird reproduction equally well; and (5) terrestrial birds for which insects are an essential source of food have declined by 2.9 billion individuals over the last 50 years, while terrestrial birds that do not depend on insects during their life history have gained by 26.2 million individuals, a 111-fold difference. Understanding the consequences of insect declines, particularly as they affect charismatic animals like birds, may motivate land managers, homeowners, and restoration ecologists to take actions that reverse these declines by favoring the native plant species that support insect herbivores most productively.

Additive negative effects of Philornis nest parasitism on small and declining Neotropical bird populations

2018 ◽  
Vol 29 (03) ◽  
pp. 339-360 ◽  
Author(s):  
MARIANA BULGARELLA ◽  
MARTÍN A. QUIROGA ◽  
GEORGE E. HEIMPEL
Keyword(s):  
Bird Species ◽  
Field Studies ◽  
Habitat Destruction ◽  
Biological Information ◽  
Mortality Factor ◽  
Healthy Population ◽  
Small Populations ◽  
Negative Effects ◽  
Nest Parasitism ◽  
Bird Populations

SummaryThe declining-population paradigm holds that small populations are particularly vulnerable to anthropogenic influences such as habitat destruction, pollution and species introductions. While the effects of particular stressors, such as parasitism, may be unimportant in a large, healthy population, they can be serious and even devastating in situations characterised by a restricted geographic range, or by fragmented or reduced population sizes. We apply this idea to nest parasitism of threatened Neotropical bird species that exist in small populations, focusing on dipteran nest parasites in the genusPhilornis. We review the literature onPhilornisparasitism exerting negative pressure on bird populations that have become small and isolated due to human actions and present a new case ofPhilornisparasitism of a threatened hummingbird species. Our aim is to raise awareness about the exacerbating effect that nest parasites can have on small and declining bird populations; especially when biological information is scarce. The five reviewed cases involve two species of Darwin’s Finches in the Galápagos Islands attacked by the invasiveP. downsi, two species of hawks on islands in the Caribbean attacked by the nativeP. piciandP. obscura, and the Yellow CardinalGubernatrix cristatain southern South America attacked by an unknownPhilornisspecies. We also present new documentation of parasitism of a threatened hummingbird species in mainland Ecuador by an unidentifiedPhilornisspecies. We recommend more field studies to determine the presence of nest parasites in bird populations worldwide to improve understanding how nest parasites affect bird fitness and population viability and to allow time to act in advance if needed. Parasitism byPhilornismay represent a severe mortality factor in most already threatened bird species, putting them at greater risk of extinction. Therefore, parasitism management should be included in all threatened species recovery plans.

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