Conservation Biology

Monteverde ◽  
2000 ◽  
Author(s):  
Nathaniel T. Wheelwright
Keyword(s):  
Conservation Biology ◽  
Bird Species ◽  
House Wren ◽  
Widespread Species ◽  
Brood Parasites ◽  
Colonizing Species ◽  
House Wrens ◽  
Moist Forest ◽  
Population Sizes ◽  
Highland Forests

Each February, when I return to Monteverde to study the reproductive ecology of lauraceous trees, I stay with friends in their farmhouse tucked on the edge of the lower montane moist forest. On my first morning back, I am always eager to listen to the dawn bird chorus. During my most recent visit, I awoke to hear a cacophony of Great-tailed Crackles, a noisy flock of Brown Jays, an exuberant House Wren, and a gang of Bronzed Cowbirds squabbling over spilled grain by the cow barn. Back in 1978, during my first visit, there were no Great-tailed Crackles in Monteverde. Brown Jays had colonized the area, but their flocks were relatively small and restricted to the lower parts of the community. House Wrens, always familiar denizens of Monteverde’s yards and farms, are more abundant today than ever. Once a rarity in Monteverde, Bronzed Cowbirds are now common. Monteverde has changed, and more changes are coming. The rest of Monteverde’s avifauna has undoubtedly felt an impact from the explosive population growth of these bird species. Crackles and jays prey on the eggs, nestlings, and fledglings of other birds; wrens also occasionally destroy other birds’ eggs. Cowbirds are brood parasites. All four species potentially compete with other species for food. Without censuses from earlier years, it is impossible to know how newly colonizing species have affected the fauna and flora of Monteverde. Contributors to this book have provided evidence that various species of animals and plants, especially widespread species of Costa Rica’s lowlands and foothills, have expanded their ranges and increased their population sizes in Monteverde. At the same time, other species are rarer than they used to be only a few decades ago. I used to marvel at the frenzied breeding aggregations of Golden Toads, hold multicolored Harlequin Frogs, and listen to nightly serenades of glass frogs along the Río Guacimal. Most of them no longer exist in Monteverde. In this chapter my goals are to (1) highlight aspects of the biodiversity of Monteverde that are relevant to conservation, (2) give a brief overview of general concepts in conservation biology, (3) discuss conservation problems that are specific to Monteverde and neotropical highland forests, and (4) consider how principles of conservation biology might provide solutions to those problems.

scholarly journals Genetic Structure in Neotropical Birds with Different Tolerance To Urbanization

2021 ◽  
Author(s):  
Mauricio Rodríguez-Bardía ◽  
Eric J. Fuchs ◽  
Gilbert Barrantes ◽  
Ruth Madrigal-Brenes ◽  
Luis Sandoval
Keyword(s):  
Gene Flow ◽  
Genetic Structure ◽  
Urban Expansion ◽  
Bird Species ◽  
Dispersal Limitation ◽  
Conservation Strategies ◽  
Urban Dweller ◽  
House Wren ◽  
House Wrens ◽  
Genetic Diversity And Structure

Abstract Gene flow in birds can be affected by urbanization depending on natural history traits and adaptability to habitat change. Contrasting results can be expected when comparing species with opposite resilience to urbanization. In this study, we assessed genetic diversity and structure for two bird species, the urban avoider white-eared ground-sparrow, Melozone leucotis, and the urban dweller house wren Troglodytes aedon. We used seven microsatellite loci and sampled five locations with differing levels of urbanization in Costa Rica. We found considerably higher genetic structure in white-eared ground-sparrows than in house wrens. Circuit theory analyses proved a higher isolation from urban resistance for the white-eared ground-sparrow than for house wrens. These results support that urbanization is a significant barrier for gene flow in urban avoiders, in contrast to urban dweller species that showed little to no impact. Differences could be attributed to a higher plasticity in habitat and nesting site preferences in the house wren, and significant dispersal limitation for the white-eared ground-sparrow. These results emphasize the need for conservation strategies towards white-eared ground-sparrows and other urban avoider species whose habitat and connectivity have been reduced by the recent urban expansion.

scholarly journals A Comparison of the Bacterial Microflora Found on the Surface of American Kestrel and House Wren Eggs

2014 ◽  
Vol 7 (1) ◽  
pp. 40-48 ◽  
Author(s):  
Beth A. Potte ◽  
Emily J. Hyde ◽  
Holly N. Pier ◽  
Michael A. Rutter ◽  
Margaret A. Voss
Keyword(s):  
Bird Species ◽  
Rrna Gene ◽  
House Wren ◽  
American Kestrel ◽  
Incubation Behavior ◽  
Gamma Proteobacteria ◽  
House Wrens ◽  
American Kestrels ◽  
The 16S Rrna Gene ◽  
Culture Dependent

It is generally accepted that avian eggs acquire a microflora during ovipositioning. The goal of this study was to identify and compare the eggshell microflora of two avian species, House Wrens and American Kestrels. Differences in the nesting habitats and incubation behavior of these species suggest that their eggshell microfloras also should differ. Culture-dependent techniques were combined with sequencing of the 16S rRNA gene to identify bacteria in samples taken from American Kestrel eggs during late incubation. These data were compared to previously collected data from House Wren eggs. In both studies, bacteria were isolated from three different phyla, Actinobacteria, Firmicutes and Proteobacteria. The eggshell microflora of Kestrels was dominated by bacteria in the Actinobacteria and Firmicutes phyla during late incubation, whereas the eggshell microflora of House Wrens was dominated by bacteria in the Gamma-Proteobacteria subphylum during pre- and late-incubation and bacteria within the Fimicutes phylum during early incubation. Actinobacteria genera on House Wren and American Kestrel eggshells differed, but the prominent genera in the Gamma- Proteobacteria and Firmicutes phyla, Pseudomonas and Staphylococcus, respectively, were similar between bird species. Thus, our results suggest that the microflora of avian eggshells have both variable (i.e., phyla) and conserved (i.e., specific genera) aspects of bacterial diversity.

scholarly journals How many bird extinctions have we prevented?

Oryx ◽  
2006 ◽  
Vol 40 (3) ◽  
pp. 266-278 ◽  
Author(s):  
Stuart H.M. Butchart ◽  
Alison J. Stattersfield ◽  
Nigel J. Collar
Keyword(s):  
Invasive Species ◽  
Captive Breeding ◽  
Extinction Risk ◽  
Bird Species ◽  
Iucn Red List ◽  
Additional Species ◽  
Conservation Actions ◽  
Declining Populations ◽  
Population Sizes ◽  
Principal Actions

Considerable resources and efforts have been directed at biodiversity conservation in recent years, but measures of the success of conservation programmes have been limited. Based on information on population sizes, trends, threatening processes and the nature and intensity of conservation actions implemented during 1994–2004, we assessed that 16 bird species would have probably become extinct during this period if conservation programmes for them had not been undertaken. The mean minimum population size of these 16 species increased from 34 to 147 breeding individuals during 1994–2004. In 1994, 63% of them had declining populations but by 2004, 81% were increasing. Most of these species (63%) are found on islands. The principal threats that led to their decline were habitat loss and degradation (88%), invasive species (50%) and exploitation (38%), a pattern similar to that for other threatened species, but with exploitation and invasive species being relatively more important. The principal actions carried out were habitat protection and management (75% of species), control of invasive species (50%), and captive breeding and release (33%). The 16 species represent only 8.9% of those currently classified as Critically Endangered, and 1.3% of those threatened with extinction. Many of these additional species slipped closer to extinction during 1994–2004, including 164 that deteriorated in status sufficiently to be uplisted to higher categories of extinction risk on the IUCN Red List (IUCN, 2006). Efforts need to be considerably scaled up to prevent many more extinctions in the coming decades. The knowledge and tools to achieve this are available, but we need to mobilize the resources and political will to apply them.

Do House Wrens (Troglodytes aedon) add spider egg cases to their nests for heterospecific cleaning?

2019 ◽  
Vol 97 (1) ◽  
pp. 50-56
Author(s):  
C.L. Gable ◽  
T.J. Underwood ◽  
G.P. Setliff
Keyword(s):  
Dna Barcoding ◽  
Body Condition ◽  
Significant Relationship ◽  
The Body ◽  
Troglodytes Aedon ◽  
House Wren ◽  
Late Season ◽  
House Wrens ◽  
Significant Difference

House Wrens (Troglodytes aedon Vieillot, 1809) regularly add spider egg cases (Arachnida: Araneae) to their nests, which may be an example of heterospecific cleaning. This behavior involves one animal employing another to remove parasites from their nests. In House Wren nests, juvenile spiders hatching from egg cases may facilitate the reduction of mites that feed on nestlings. We tested this ectoparasite reduction hypothesis by monitoring House Wren nests for spider egg cases and by collecting completed nests to compare the number of spider egg cases and Dermanyssus hirundinis (Hermann, 1804) mites. No significant relationship was found between the number of spider egg cases and number of D. hirundinis mites in nests. We also found no significant relationship between the number of D. hirundinis mites in nests and the body condition of nestlings. Finally, no significant difference was found between the number of D. hirundinis mites in early versus late season nests, but significantly more spider egg cases were added to late season nests. Of a subsample of spider egg cases dissected, we found that 28% contained spider eggs or embryos. We also identified three species of juvenile spiders from House Wren nests using DNA barcoding. Overall, we found no evidence that spider egg cases reduce the number of D. hirundinis mites or engender better quality offspring in House Wren nests.

Status, Distribution, and Conservation of Native Freshwater Fishes of Western North America

2007 ◽  
Keyword(s):  
Conservation Biology ◽  
Biological Diversity ◽  
Common Species ◽  
Model System ◽  
Future Research ◽  
Evolutionary Processes ◽  
Widespread Species ◽  
Key Points ◽  
Management Priorities ◽  
Conservation And Management

ABSTRACT The fundamental charge of conservation biology is to preserve biological diversity. Yet, efforts to accomplish this goal have focused too narrowly on reversing the slide toward extinction in already threatened or endangered species. In this review, we argue that conservation biologists and fisheries managers should broaden their vision to include efforts to preserve the ecological and evolutionary processes that ultimately give rise to new biodiversity. Our view is based upon the simple observation that biological diversity is a function of both the rate at which new taxa originate as well as the rate at which established taxa are lost to extinction. Efforts to stem extinction that fail to maintain the ecological and evolutionary processes of speciation are ultimately unsustainable. We suggest that common, widespread species are particularly important to the origin of new diversity and argue that conservation biologists should pay particular attention to the evolution of diversity within such species. We illustrate several key points to this argument using the desert minnow, Utah chub <em>Gila atraria</em>, as a model system. In particular, we show that conservation efforts in common species must focus on clearly delineating conservation unit boundaries and that particular care should be paid to unique ecological and evolutionary diversity within such species.We also show the importance of understanding and conserving the range of ecological and evolutionary interactions that are common hallmarks of abundant and widespread taxa.We conclude our review by suggesting several specific areas of future research in Utah chub that would help more clearly define conservation and management priorities in this species.

scholarly journals Artificial Wetlands as Breeding Habitats for Colonial Waterbirds within Central Romania

Diversity ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 371
Author(s):  
Dan Traian Ionescu ◽  
Călin Vasile Hodor ◽  
Ion Cătălin Petritan
Keyword(s):  
Conservation Status ◽  
Bird Species ◽  
Natura 2000 ◽  
Positive Trend ◽  
Phalacrocorax Carbo ◽  
Artificial Wetlands ◽  
Nycticorax Nycticorax ◽  
Ardea Alba ◽  
Colonial Waterbirds ◽  
Population Sizes

The historical loss of natural wetlands in Romania is significant. The building of lakes, ponds, and dams has compensated for some of these losses, as was the case in the study area, the artificial wetlands designated as the Natura 2000 (special protection area, SPA) and Ramsar sites. In this context, to evaluate the conservation status of colonial waterbirds (cormorants, herons, and egrets), we analyzed actual distributions, habitat selection, features, and population sizes. Standardized counting of colonial species was used, supplemented by nest counting and colony-area estimation during winter, and drone footage. All species and their colonies were built in artificial or anthropically influenced habitats. Concerning distribution and population sizes, Phalacrocorax carbo and Microcarbo pygmeus were found to nest only in central Romania. The pair numbers of Ardea alba, Ardea purpurea, Ardea cinerea, and Nycticorax nycticorax in the area exceeded 1% of the national minimum breeding population. There was a statistically significant positive trend of breeding populations for Ardea alba, Nycticorax nycticorax, and Egretta garzetta. In conclusion, these artificial wetlands offer optimal breeding conditions for a relatively large diversity of colonial bird species over areas that are not very large.

Sightability as a Factor in Aerial Survey of Bird Species and Communities

1985 ◽  
Vol 12 (1) ◽  
pp. 57 ◽  
Author(s):  
LS Broome
Keyword(s):  
New England ◽  
Water Body ◽  
Bird Species ◽  
Abundant Species ◽  
Common Species ◽  
Aerial Survey ◽  
Flying Height ◽  
South Wales ◽  
Population Sizes ◽  
Bodies Of Water

Experimental aerial and ground censuses of waterbirds were conducted on three small, isolated bodies of water on the New England tablelands of New South Wales. The flying height at which sightability was optimized for the most common species was 30 m. Aerial and ground counts were significantly correlated for most species on the three watar bodies. Black swan, swamphen, coots, musk ducks and maned ducks were counted in equivalent or greater numbers from the air than from the ground on at least one water body. Other species were counted in lower numbers from the air than from the ground. A fairly high precision in the aerial-ground relationship for the most abundant species indicates that aerial survey can be a useful procedure for obtaining indices or estimates of the population sizes of these species. However, differences in sightability between species and between types of water body indicate that indices should be used and interpreted with caution. Other bird species from a variety of habitat types which are also amenable to aerial survey are discussed, and some recommendations for aerial surveys of birds are provided.

scholarly journals Host alarm calls attract the unwanted attention of the brood parasitic common cuckoo

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Attila Marton ◽  
Attila Fülöp ◽  
Katalin Ozogány ◽  
Csaba Moskát ◽  
Miklós Bán
Keyword(s):  
Bird Species ◽  
Context Dependency ◽  
Visual Signals ◽  
Alarm Calls ◽  
Primary Host ◽  
Nest Location ◽  
Brood Parasites ◽  
Body Of Knowledge ◽  
Vantage Points

AbstractIt is well known that avian brood parasites lay their eggs in the nests of other bird species, called hosts. It remains less clear, however, just how parasites are able to recognize their hosts and identify the exact location of the appropriate nests to lay their eggs in. While previous studies attributed high importance to visual signals in finding the hosts’ nests (e.g. nest building activity or the distance and direct sight of the nest from vantage points used by the brood parasites), the role of host acoustic signals during the nest searching stage has been largely neglected. We present experimental evidence that both female and male common cuckoos Cuculus canorus pay attention to their host’s, the great reed warbler’s Acrocephalus arundinaceus alarm calls, relative to the calls of an unparasitized species used as controls. Parallel to this, we found no difference between the visibility of parasitized and unparasitized nests during drone flights, but great reed warblers that alarmed more frequently experienced higher rates of parasitism. We conclude that alarm calls might be advantageous for the hosts when used against enemies or for alerting conspecifics, but can act in a detrimental manner by providing important nest location cues for eavesdropping brood parasites. Our results suggest that host alarm calls may constitute a suitable trait on which cuckoo nestlings can imprint on to recognize their primary host species later in life. Our study contributes to the growing body of knowledge regarding the context-dependency of animal signals, by providing a novel example of a beneficial acoustic trait intercepted by a heterospecific and used against the emitter.

Parasitism of House Wren nests by Brown-headed Cowbirds: why is it so rare?

1997 ◽  
Vol 75 (2) ◽  
pp. 302-307 ◽  
Author(s):  
Stanislav Pribil ◽  
Jaroslav Picman
Keyword(s):  
Field Experiments ◽  
Molothrus Ater ◽  
Low Frequency ◽  
Nest Material ◽  
Nest Structure ◽  
Troglodytes Aedon ◽  
House Wren ◽  
House Wrens ◽  
Nest Desertion ◽  
Cowbird Parasitism

We tested five hypotheses that may explain why House Wren (Troglodytes aedon) nests are rarely parasitized by Brown-headed Cowbirds (Molothrus ater). House Wrens may prevent parasitism in five ways: (1) by choosing to nest in cavities with small entrances (inaccessible-entrance hypothesis), (2) by restricting the size of the entrance with nest material (nest-structure hypothesis), (3) by puncturing and ejecting parasitic eggs (puncture–ejection hypothesis), (4) by burying the parasitized clutch under a new nest (egg-burial hypothesis), or (5) by abandoning the parasitized nest altogether (nest-desertion hypothesis). We tested these hypotheses in field experiments and found that (i) female cowbirds cannot enter circular entrances smaller than 38 mm in diameter, (ii) wrens prefer cavities with small entrances (inaccessible to cowbirds) to those with large entrances (accessible to cowbirds), (iii) when forced to breed in cavities with large entrances, wrens do not reduce the entrance size with nest material, (iv) despite the unusual strength of cowbird eggs, wrens are physically capable of puncture–ejecting them, (v) wrens do not puncture–eject cowbird eggs from their own nests, (vi) wrens do not abandon parasitized nests or bury the parasitized clutches under new nests. These results are consistent with the inaccessible-entrance hypothesis. We propose that additional nesting adaptations, as well as active cowbird avoidance of House Wrens, may contribute to the low frequency of cowbird parasitism.

scholarly journals Contribution of a mutational hot spot to hemoglobin adaptation in high-altitude Andean house wrens

2015 ◽  
Vol 112 (45) ◽  
pp. 13958-13963 ◽  
Author(s):  
Spencer C. Galen ◽  
Chandrasekhar Natarajan ◽  
Hideaki Moriyama ◽  
Roy E. Weber ◽  
Angela Fago ◽  
...  
Keyword(s):  
High Altitude ◽  
Hot Spot ◽  
Globin Gene ◽  
Single Point ◽  
Evolutionary Genetics ◽  
Single Point Mutation ◽  
Phenotypic Evolution ◽  
House Wren ◽  
House Wrens ◽  
Low Altitude

A key question in evolutionary genetics is why certain mutations or certain types of mutation make disproportionate contributions to adaptive phenotypic evolution. In principle, the preferential fixation of particular mutations could stem directly from variation in the underlying rate of mutation to function-altering alleles. However, the influence of mutation bias on the genetic architecture of phenotypic evolution is difficult to evaluate because data on rates of mutation to function-altering alleles are seldom available. Here, we report the discovery that a single point mutation at a highly mutable site in the βA-globin gene has contributed to an evolutionary change in hemoglobin (Hb) function in high-altitude Andean house wrens (Troglodytes aedon). Results of experiments on native Hb variants and engineered, recombinant Hb mutants demonstrate that a nonsynonymous mutation at a CpG dinucleotide in the βA-globin gene is responsible for an evolved difference in Hb–O2 affinity between high- and low-altitude house wren populations. Moreover, patterns of genomic differentiation between high- and low-altitude populations suggest that altitudinal differentiation in allele frequencies at the causal amino acid polymorphism reflects a history of spatially varying selection. The experimental results highlight the influence of mutation rate on the genetic basis of phenotypic evolution by demonstrating that a large-effect allele at a highly mutable CpG site has promoted physiological differentiation in blood O2 transport capacity between house wren populations that are native to different elevations.

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