Landscape‐scale habitat characteristics and neonatal white‐tailed deer survival

For many marine systems, little is known about the effects of habitat structure on ecological processes that dictate population dynamics. This study focused on the effects of habitat structure on behaviour, abundance, and survival of California spiny lobster (Panulirus interruptus Randall) in the Point Loma kelp forest, San Diego, California. Habitat characteristics were quantified in 400-m2 landscapes to determine the role of shelter and understorey kelp characteristics at local (shelter) scales and landscape scales on lobster habitat use. A tethering experiment determined the effects of the presence of understorey kelp on lobster survival. At the shelter scale, lobsters preferred permanent shelters to ephemeral shelters, but did not respond to shelter size. At the landscape scale, lobster density increased with Pterygophora californica (stipitate kelp) density and decreased with Laminaria farlowii (prostrate kelp) density, but lobster density did not vary with shelter density or dispersion. Lobster size increased with P. californica density in two of three surveys, while lobster size did not vary with L. farlowii density. Lobster relative survival was higher in the presence of understorey kelp than when kelp was absent. We conclude that lobsters respond to habitat characteristics at local and landscape scales, and that understorey kelp has strong effects on lobster habitat use and survival.

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Correlation of Red-Shouldered Hawk Abundance and Macrohabitat Characteristics in Southern Ohio

The Condor ◽

10.1093/condor/103.3.652 ◽

2001 ◽

Vol 103 (3) ◽

pp. 652-656

Author(s):

Cheryl R. Dykstra ◽

F. Bernard Daniel ◽

Jeffrey L. Hays ◽

Melinda M. Simon

Keyword(s):

Response Rate ◽

Landscape Scale ◽

Data Grid ◽

Habitat Characteristics ◽

Abundance Index ◽

Buteo Jamaicensis ◽

The Mean ◽

Study Sites ◽

Permanent Stream

Abstract We measured an index of Red-shouldered Hawk (Buteo lineatus) abundance along streams in southern Ohio and related differences in abundance index to landscape-scale habitat characteristics within the surveyed areas. Fifteen study sites, each a 5.8-km reach of a permanent stream, were surveyed four times using broadcasts of Red-shouldered Hawk calls and Red-tailed Hawk (Buteo jamaicensis) calls. We determined the landcover types in a corridor surrounding each surveyed area using a GIS landcover data grid, and counted the number of small ponds within each corridor. We calculated hawk response rate for each species as the mean number of visual or aural detections per survey. Red-shouldered Hawk response rate was inversely correlated to Red-tailed Hawk response rate (r = −0.52, P < 0.04), and was positively correlated to the number of small ponds within each stream corridor (r = 0.77, P < 0.01), suggesting that the number of small ponds was an important factor associated with Red-shouldered Hawk abundance. Correlación entre la Abundancia de Buteo lineatus y Características de Macrohábitat en el Sur de Ohio Resumen. Calculamos un índice de abundancia de Buteo lineatus a lo largo de varios arroyos en el sur de Ohio y relacionamos las diferencias en este índice con características del hábitat a escala del paisaje de las áreas censadas. Trabajamos en 15 sitios (cada uno comprendiendo 5.8 km alrededor de un arroyo permanente), que fueron censados cuatro veces reproduciendo vocalizaciones de B. lineatus y B. jamaicensis. Determinamos el tipo de uso de la tierra en un corredor alrededor de cada área censada utilizando un sistema de información geográfica y contamos el número de pequeños estanques al interior de cada corredor. Calculamos la tasa de respuesta de las dos especies de gavilanes como el número promedio de detecciones visuales o auditivas por censo. La tasa de respuesta de B. lineatus se correlacionó negativamente con la tasa de respuesta de B. jamaicensis (r = −0.52, P < 0.04) y positivamente con el número de estanques dentro de cada corredor (r = 0.77, P < 0.01). Los resultados sugieren que el número de estanques es un factor importante asociado a la abundancia de B. lineatus.

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The effects of spatial survey bias and habitat suitability on predicting the distribution of threatened species living in remote areas

Bird Conservation International ◽

10.1017/s0959270917000144 ◽

2017 ◽

Vol 28 (4) ◽

pp. 581-592 ◽

Cited By ~ 4

Author(s):

LAURA CARDADOR ◽

JOSÉ A. DÍAZ-LUQUE ◽

FERNANDO HIRALDO ◽

JAMES D. GILARDI ◽

JOSÉ L. TELLA

Keyword(s):

Land Use ◽

Geographical Distribution ◽

Species Distribution ◽

Potential Distribution ◽

Variation Partitioning ◽

Sampling Bias ◽

Landscape Scale ◽

Habitat Characteristics ◽

Distribution Models ◽

Joint Contribution

SummaryKnowledge of a species’ potential distribution and the suitability of available habitat are fundamental for effective conservation planning and management. However, the quality of information on the distribution of species and their required habitats is highly variable in terms of accuracy and availability across taxa and regions, particularly in tropical landscapes where accessibility is especially challenging. Species distribution models (SDMs) provide predictive tools for addressing gaps for poorly surveyed species, but they rarely consider biases in geographical distribution of records and their consequences. We applied SDMs and variation partitioning analyses to investigate the relative importance of habitat characteristics, human accessibility, and their joint effects in the global distribution of the Critically Endangered Blue-throated MacawAra glaucogularis, a species endemic to the Amazonian flooded savannas of Bolivia. The probability of occurrence was skewed towards more accessible areas, mostly secondary roads. Variability in observed occurrence patterns was mostly accounted for by the pure effect of habitat characteristics (76.2%), indicating that bias in the geographical distribution of occurrences does not invalidate species-habitat relationships derived from niche models. However, observed spatial covariation between land-use at a landscape scale and accessibility (joint contribution: 22.3%) may confound the independent role of land-use in the species distribution. New surveys should prioritise collecting data in more remote (less accessible) areas better distributed with respect to land-use composition at a landscape scale. Our results encourage wider application of partitioning methods to quantify the extent of sampling bias in datasets used in habitat modelling for a better understanding of species-habitat relationships, and add insights into the potential distribution of our study species and opportunities for its conservation.

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