Habitat loss

Changes in the status and distribution of Wisconsin's double-crested cormorant (DCCO) breeding population during the 20th century closely approximate a similar pattern throughout the Great Lakes and generally along the Atlantic coast: a gradual increase in popula- tion size from about 1921 until about 1950, followed by a population crash, and then a remarkable population resurgence beginning in the early

The Cape Dwarf Chameleon (Bradypodion pumilum) is an endemic South African species that is currently threatened by habitat loss and fragmentation of its natural habitat through urbanization and agriculture. To conduct studies that will assist in understanding these anthropogenic effects on gene flow, population structure, and genetic diversity, we developed eight microsatellite loci using an enrichment protocol. Number of alleles ranged from 5 to 26 with observed heterozygosities of 0.279–0.930. Several loci did not meet HW expectations, but this may be a result of extreme demographic fluctuations that have been noted for this species. These loci will prove useful to examine the population genetics of these threatened reptiles and for providing information that will be used for generating and updating conservation assessments.

Abstract: Oceania is a diverse region encompassing Australia, Melanesia, Micronesia, New Zealand, and Polynesia, and it contains six of the world's 39 hotspots of diversity. It has a poor record for extinctions, particularly for birds on islands and mammals. Major causes include habitat loss and degradation, invasive species, and overexploitation. We identified six major threatening processes (habitat loss and degradation, invasive species, climate change, overexploitation, pollution, and disease) based on a comprehensive review of the ...

Human intervention in the hydrologic basin of the Colorado River has eliminated water discharge and sediment supply to the river's mouth and its delta. After ∼95 years of applying strong flow control policies, the previous sedimentary budget in the delta has changed, the delta now being entirely exposed to the hydrodynamic forces in its basin. In order to assess the anthropogenic impact of water diversion on deltaic sedimentary processes and short-term delta geomorphic evolution, textural and mineralogical analyses were performed on 68 sediment samples collected from the river, estuary, beach, continental shelf, delta plain and desert. The results show a consistent NE to SW textural gradient on the shallow-marine platform adjacent to the Colorado River delta (an area known as the Upper Gulf of California), and a net cross-basinal sediment transport occurring in the same direction. Two opposing littoral transport components exist along the Sonoran and Baja Californian coasts: (1) net sediment transport from SE to NW along the Sonoran coast delivers sediments from the ocean into the estuarine basin through the Sonora channel of the deltaic system of the Colorado River; and (2) sediment transport from N to S along the Baja Californian coast removes sediments from the estuarine basin of the Colorado River into the Northern Gulf of California (NGC). The residual sediment transport pattern observed suggests a counterclockwise path of exchange of materials between the estuarine basin of the Colorado River and the NGC. Multivariate cluster and factor analyses of the heavy-mineral data reveal the existence of a sedimentary system dominated by two end-members, representing two heavy-mineral sedimentary provinces: (1) the Sonora province is characterized by a heavy-mineral suite of garnet and zircon (G–Z), whose sediment supply originates from the sandy sediments of the Sonora Mesa deposits and Sonora's Gran Desierto; and (2) the Baja California province is characterized by a hornblende–epidote–pyroxene (H–E–P) suite, whose sediments originate from the earlier supply of the Colorado River. Since the Colorado River is no longer supplying sediments from its drainage basin, the H–E–P-rich sediments now actively dispersed in the system have mainly originated through intense reworking of the delta. Moreover, G–Z-rich sediments are starting to invade areas previously dominated by H–E–P sediments. On the basis of the prevailing hydraulic regime, textural and mineralogical characteristics of the sediments, and hydrographic and bathymetric information from the region, a hypothetical sediment dynamics model for the delta region is proposed, in which the tidally influenced, wave-dominated, sediment-reworked, slightly eroding Sonoran coast changes into a tide-dominated, depositional, very slowly prograding Baja Californian coast. This study shows that human intervention of the hydrologic basin of the Colorado River is not only responsible for inducing drastic hydrologic changes in its estuary (i.e., from brackish to hypersaline), but also for inducing drastic changes in the hydrographic circulation of the receiving basin (i.e., from long-basinal to cross-basinal). These changes are ultimately responsible for the relocation of massive volumes of the delta's sediment inventory, and for the serious ecological impact of habitat loss of indigenous species, such as the now endangered Totoaba (Totoaba macdonaldi) and Vaquita (Phocoena sinus).

Human activity during the Anthropocene has transformed landscapes worldwide on a scale that rivals or exceeds even the largest of natural forces. Landscape ecology has emerged as a science to investigate the interactions between natural and anthropogenic landscapes and ecological processes across a wide range of scales and systems: from the effects of habitat or resource distributions on the individual movements, gene flow, and population dynamics of plants and animals; to the human alteration of landscapes affecting the structure of biological communities and the functioning of entire ecosystems; to the sustainable management of natural resources and the ecosystem goods and services upon which society depends. This novel and comprehensive text presents the principles, theory, methods, and applications of landscape ecology in an engaging and accessible format that is supplemented by numerous examples and case studies from a variety of systems, including freshwater and marine "scapes".

Essentials of Landscape Ecology is suitable for upper-level undergraduate and graduate courses in landscape ecology. This textbook can also be used as a supplemental text in other ecology courses, as well as courses in forestry, resource and wildlife management, conservation and restoration biology, sustainable land-use and environmental planning.  For the professional landscape ecologist, it provides an authoritative overview of the latest research and developments.

Available through all major booksellers or directly from Oxford University Press:
https://global.oup.com/academic/product/essentials-of-landscape-ecology-9780198838388

Coastal prairies are the primary winter destination for two dozen species of migratory grassland birds and losses of this habitat have proven detrimental to their populations. As a result, some of Partners in Flight's (PIF) highest priority birds are grassland species. To examine grassland bird use of coastal prairies, Project Prairie Birds survey methodology was designed and field work was initiated in 1998. Avian surveys were conducted at 34 sites, each with multiple tran- sects for a minimum of two years by all-volunteer, three-person crews identifying all species flushed from vegetation. Seasonal vegetation surveys measured five variables using five one square-meter sample areas. We also measured vertical thickness using a density board. We selected nine sites (26.5%) with three or more years of survey data for analysis. Thirty-nine species were detected of which 36% have PIF combined species assessment scores of 10 or above. In addition, 24% of the individuals were Le Conte...

Abstract Papua New Guinea (PNG) sustains some of the world's most biologically and culturally rich forests. Like many tropical nations, PNG is changing rapidly as it attempts to develop economically, but corporate misdealing and weak governance are undermining its capacity to do so sustainably. Overexploitation of forests is rampant, with most accessible forests likely to be logged or disappear in 1–2 decades.

Aim: Understanding how habitat loss and overhunting impact large carnivores is important for broad-scale conservation planning. We aimed to assess how these threats interacted to affect jaguar habitat (Panthera onca) between 1985-2013 in the Gran Chaco, a deforestation hotspot.

Location: Gran Chaco ecoregion in Argentina, Paraguay and Bolivia. Methods: We modelled jaguar habitat change from 1985-2013 using a time-calibrated species distribution model that uses all occurrence data available for that period. We modelled habitat as a function of resource availability and hunting threats, which allowed us to separate core (high resource availability and low hunting threat), refuge (low resources but safe), attractive sink (high resources but risky) and sink (low resources and risky) habitat for 1985, 2000 and 2013.

Results: Jaguar core areas contracted by 33% (82,400 km 2) from 1985-2013, mainly due to an expansion of hunting threats. Sink and attractive sink habitat covered 58% of the jaguar range in 2013 and most confirmed jaguar kill sites occurred in these.

Dans les sociétés occidentales modernes, les personnes exclues du logement de droit commun sont très minoritaires mais leur nombre a augmenté ces dernières années. Elles se retrouvent dans diverses situations d’habitat : hébergements chez des particuliers, dans des institutions, des hôtels à leurs frais, des squats, d’autres habitats de fortune ou encore sans abri. Cette dernière situation suscite beaucoup d’interrogations : comment se fait-il que des personnes ne recourent pas aux hébergements sociaux et dorment à la rue ? Une raison parfois avancée dans le monde politique ou le grand public est le « choix personnel ». D’autres parlent de cas psychiatriques. Deux autres causes souvent avancées sont le manque de places disponibles, et l’effet de dissuasion lié à de nombreux refus par manque de place ou aux conditions d’hébergement jugées indignes dans certains centres d’urgence. Comment faire la part entre ces diverses explications ? Et ne peut-on pas en envisager d’autres ?
Cette étude apporte un éclairage quelque peu différent sur cette question. Elle s’intéresse principalement aux personnes en situation de non-recours durable (au moins plusieurs mois), et notamment à celles qui ne demandent plus d’hébergement, voire refusent les places qui leur sont proposées. Elle mobilise à la fois des techniques statistiques, par l’exploitation des données issues de l’enquête HYTPEAC (2011), et des techniques de recherche qualitative, permettant d’accéder directement aux personnes concernées.
Cette étude apporte deux résultats principaux. Le premier souligne que toutes les personnes sans domicile n’ont pas les mêmes probabilités de recours aux hébergements sociaux, et conduit à interroger les pratiques de priorisation à l’œuvre dans le système de prise en charge. Le second résultat, qui concerne spécifiquement les personnes sans abri sédentarisées depuis au moins plusieurs mois, voire années, explique les refus de places pourtant disponibles par la difficulté rencontrée par ces personnes pour casser les relations signifiantes qu’elles ont nouées dans un environnement qui les expose pourtant à une dégradation de leur état de santé et à des violences.
Ces deux résultats invitent à reconsidérer ce qui est appelé « la grande exclusion » à l’aune de sa dimension collective. Plutôt que d'expliquer le sans-abrisme de longue durée par des choix individuels, et d'en déduire que le mieux est de ne pas intervenir, le regard sociologique sur ces situations limites apporte de nouvelles perspectives et ouvre une réflexion sur la création d'un "droit à habiter".