Visibility Bias of Waterbirds During Aerial Surveys in the Nonbreeding Season

2021 ◽  
Author(s):  
Andrew D. Gilbert ◽  
Christopher N. Jacques ◽  
Joseph D. Lancaster ◽  
Aaron P. Yetter ◽  
Heath M. Hagy
Keyword(s):  
Nonbreeding Season ◽  
Aerial Surveys

Profiles of gamma-ray and magnetic data from aerial surveys over the conterminous United States

Data Series ◽  
10.3133/ds31 ◽  
1999 ◽  
Author(s):  
Joseph S. Duval ◽  
Frederic E. Riggle
Keyword(s):  
United States ◽  
Gamma Ray ◽  
Magnetic Data ◽  
Aerial Surveys

scholarly journals Population estimates of Antillean manatees in Puerto Rico: an analytical framework for aerial surveys using multi-pass removal sampling

2019 ◽  
Vol 100 (4) ◽  
pp. 1340-1349
Author(s):  
Jaime A Collazo ◽  
Matthew J Krachey ◽  
Kenneth H Pollock ◽  
Francisco J Pérez-Aguilo ◽  
Jan P Zegarra ◽  
...  
Keyword(s):  
Puerto Rico ◽  
Detection Probability ◽  
Analytical Framework ◽  
Population Estimates ◽  
High Concentration ◽  
Imperfect Detection ◽  
Factors Affecting ◽  
Management Actions ◽  
Aerial Surveys ◽  
Population Size Estimates

AbstractEffective management of the threatened Antillean manatee (Trichechus manatus manatus) in Puerto Rico requires reliable estimates of population size. Estimates are needed to assess population responses to management actions, and whether recovery objectives have been met. Aerial surveys have been conducted since 1976, but none adjusted for imperfect detection. We summarize surveys since 1976, report on current distribution, and provide population estimates after accounting for apparent detection probability for surveys between June 2010 and March 2014. Estimates in areas of high concentration (hotspots) averaged 317 ± 101, three times higher than unadjusted counts (104 ± 0.56). Adjusted estimates in three areas outside hotspots also differed markedly from counts (75 ± 9.89 versus 19.5 ± 3.5). Average minimum island-wide estimate was 386 ± 89, similar to the maximum estimate of 360 suggested in 2005, but fewer than the 700 recently suggested by the Puerto Rico Manatee Conservation Center. Manatees were more widespread than previously understood. Improving estimates, locally or island-wide, will require stratifying the island differently and greater knowledge about factors affecting detection probability. Sharing our protocol with partners in nearby islands (e.g., Cuba, Jamaica, Hispaniola), whose populations share genetic make-up, would contribute to enhanced regional conservation through better population estimates and tracking range expansion.El manejo efectivo del manatí antillano amenazado en Puerto Rico requiere estimados de tamaños de poblaciónes confiables. Dichas estimaciones poblacionales son necesarias para evaluar las respuestas a las acciones de manejo, y para determinar si los objetivos de recuperación han sido alcanzados. Se han realizado censos aéreos desde 1976, pero ninguno de ellos han sido ajustados para detecciones imperfectas. Aquí resumimos los censos desde 1976, actualizamos la distribución, y reportamos los primeros estimados poblacionales ajustados para la probabilidad de detección aparente en los censos de Junio 2010 a Marzo 2014. Las estimaciones poblacionales en áreas de mayor concentración del manatí promedió 317 ± 103, tres veces más abundante que los conteos sin ajuste (104 ± 0.56). Las estimaciones poblacionales en tres áreas fuera de las áreas de mayor concentración del manatí también fueron marcadamente diferentes (75 ± 9.89 vs 19.5 ± 3.5). El estimado mínimo poblacional en la isla entera fue de 386 ± 89, similar al estimado máximo de 360 sugerido en el año 2005, pero menor a los 700 sugeridos recientemente por el Centro de Conservación de Manatíes de Puerto Rico. Documentamos que el manatí tiene una distribución más amplia de lo que se sabía con anterioridad. El mejoramiento de los estimados poblacionales locales o a nivel de isla requerirá que se estratifique a la isla en forma diferente y que se investiguen los factores que influencian a la probabilidad de detección. Compartir protocolos como este con colaboradores de islas vecinas (por. ej., Cuba, Jamaica, Española), cuyas poblaciones de manatíes comparten material genético, contribuiría a la conservación regional mediante mejores estimaciones poblacionales y monitoreo de la expansión de su ámbito doméstico.

scholarly journals Drivers of Bornean Orangutan Distribution across a Multiple-Use Tropical Landscape

2021 ◽  
Vol 13 (3) ◽  
pp. 458
Author(s):  
Sol Milne ◽  
Julien G. A. Martin ◽  
Glen Reynolds ◽  
Charles S. Vairappan ◽  
Eleanor M. Slade ◽  
...  
Keyword(s):  
Forest Cover ◽  
Food Resource ◽  
Multiple Use ◽  
Natural Forests ◽  
Bornean Orangutan ◽  
Aerial Surveys ◽  
Significant Difference ◽  
The Difference ◽  
Fig Trees ◽  
Abundance And Distribution

Logging and conversion of tropical forests in Southeast Asia have resulted in the expansion of landscapes containing a mosaic of habitats that may vary in their ability to sustain local biodiversity. However, the complexity of these landscapes makes it difficult to assess abundance and distribution of some species using ground-based surveys alone. Here, we deployed a combination of ground-transects and aerial surveys to determine drivers of the critically endangered Bornean Orangutan (Pongo pygmaeus morio) distribution across a large multiple-use landscape in Sabah, Malaysian Borneo. Ground-transects and aerial surveys using drones were conducted for orangutan nests and hemi-epiphytic strangler fig trees (Ficus spp.) (an important food resource) in 48 survey areas across 76 km2, within a study landscape of 261 km2. Orangutan nest count data were fitted to models accounting for variation in land use, above-ground carbon density (ACD, a surrogate for forest quality), strangler fig density, and elevation (between 117 and 675 m). Orangutan nest counts were significantly higher in all land uses possessing natural forest cover, regardless of degradation status, than in monoculture plantations. Within these natural forests, nest counts increased with higher ACD and strangler fig density, but not with elevation. In logged forest (ACD 14–150 Mg ha−1), strangler fig density had a significant, positive relationship with orangutan nest counts, but this relationship disappeared in a forest with higher carbon content (ACD 150–209 Mg ha−1). Based on an area-to-area comparison, orangutan nest counts from ground transects were higher than from counts derived from aerial surveys, but this did not constitute a statistically significant difference. Although the difference in nest counts was not significantly different, this analysis indicates that both methods under-sample the total number of nests present within a given area. Aerial surveys are, therefore, a useful method for assessing the orangutan habitat use over large areas. However, the under-estimation of nest counts by both methods suggests that a small number of ground surveys should be retained in future surveys using this technique, particularly in areas with dense understory vegetation. This study shows that even highly degraded forests may be a suitable orangutan habitat as long as strangler fig trees remain intact after areas of forest are logged. Enrichment planting of strangler figs may, therefore, be a valuable tool for orangutan conservation in these landscapes.

scholarly journals Assessment and novel application of N ‐mixture models for aerial surveys of wildlife

Ecosphere ◽  
2021 ◽  
Vol 12 (8) ◽  
Author(s):  
Sonja A. Christensen ◽  
Matthew T. Farr ◽  
David M. Williams
Keyword(s):  
Mixture Models ◽  
Aerial Surveys

Correcting for Visibility Bias in Strip Transect Aerial Surveys of Aquatic Fauna

1989 ◽  
Vol 53 (4) ◽  
pp. 1017 ◽  
Author(s):  
H. Marsh ◽  
D. F. Sinclair
Keyword(s):  
Aquatic Fauna ◽  
Aerial Surveys ◽  
Strip Transect

Effect of Melatonin on Telocytes in the Seminal Vesicle of the Soay Ram: An Immunohistochemical, Ultrastructural and Morphometrical Study

2016 ◽  
Vol 203 (1) ◽  
pp. 29-54 ◽  
Author(s):  
Hanan H. Abd-Elhafeez ◽  
Doaa M. Mokhtar ◽  
Ahmed H.S. Hassan
Keyword(s):  
Close Contact ◽  
Intercellular Junctions ◽  
Secretory Activity ◽  
Treated Group ◽  
Control Group ◽  
Secretory Vesicles ◽  
Melatonin Treatment ◽  
Secretory Structures ◽  
Strong Reaction ◽  
Nonbreeding Season

Telocytes (TCs) are a special type of interstitial cell with characteristic cellular processes that are described in many organs. The current study aimed to investigate TCs in seminal vesicles of the Soay ram responding to melatonin treatment during the nonbreeding season by conventional immunohistochemical stains, and to detect the ultrastructural and morphometrical changes of TCs. TCs in the control group showed a broad range of staining affinity and also reacted positively to CD117/c-kit, CD34, desmin, S-100 protein, and progesterone and estrogen receptors alpha, while after melatonin treatment a strong reaction against these 6 antibodies was recorded. Electron microscopically, TCs in the control group were characterized by a small cell body with distinct long cytoplasmic extensions called telopodes (Tps). Tps had alternation of the thin segment (podomers) and dilated segments (podoms), in which the latter accommodate mitochondria, rough endoplasmic reticulum and caveolae. TCs and their Tps were interconnected by homo- and heterocellular junctions and form a wide network to communicate between different cell types. Tps showed close contact with immune cells, progenitor stem cells, smooth muscle cells and other interstitial cells. Melatonin caused a significant increase in the number of TCs, length of Tps, and number and diameter of secretory vesicles. Also, the melatonin-treated group showed exaggerated secretory activity in the form of a massive release of secretory vesicles from Tps. Moreover, Tps showed an increase in their contact with blood and lymphatic capillaries, nerve endings and Schwann cells. In addition, the shedding of secretory structures (exosomes, ectosomes, and multivesicular bodies) was greater from Tps, which were involved in paracrine signaling in the melatonin-treated group. The length and ramifications of Tps together with the intercellular junctions and the releasing of shed vesicles or exosomes assumed an essential role of TCs in intercellular signaling and coordination. On the basis of their distribution and morphology, we investigated whether the different locations of TCs could be associated with different roles.

Change in abundance of dugongs in Shark Bay, Ningaloo and Exmouth Gulf, Western Australia: evidence for large-scale migration

2004 ◽  
Vol 31 (3) ◽  
pp. 283 ◽  
Author(s):  
Nick Gales ◽  
Robert D. McCauley ◽  
Janet Lanyon ◽  
Dave Holley
Keyword(s):  
Marine Protected Areas ◽  
Large Scale ◽  
Population Demographics ◽  
Shark Bay ◽  
Ningaloo Reef ◽  
Aerial Surveys ◽  
Large Numbers ◽  
Plausible Hypothesis ◽  
Exmouth Gulf ◽  
Regional Abundance

The third in a series of five-yearly aerial surveys for dugongs in Shark Bay, Ningaloo Reef and Exmouth Gulf was conducted in July 1999. The first two surveys provided evidence of an apparently stable population of dugongs, with ~1000 animals in each of Exmouth Gulf and Ningaloo Reef, and 10 000 in Shark Bay. We report estimates of less than 200 for each of Exmouth Gulf and Ningaloo Reef and ~14 000 for Shark Bay. This is an apparent overall increase in the dugong population over this whole region, but with a distributional shift of animals to the south. The most plausible hypothesis to account for a large component of this apparent population shift is that animals in Exmouth Gulf and Ningaloo Reef moved to Shark Bay, most likely after Tropical Cyclone Vance impacted available dugong forage in the northern habitat. Bias associated with survey estimate methodology, and normal changes in population demographics may also have contributed to the change. The movement of large numbers of dugongs over the scale we suggest has important management implications. First, such habitat-driven shifts in regional abundance will need to be incorporated in assessing the effectiveness of marine protected areas that aim to protect dugongs and their habitat. Second, in circumstances where aerial surveys are used to estimate relative trends in abundance of dugongs, animal movements of the type we propose could lead to errors in interpretation.

Winter coexistence of voles in spruce forest: relevance of seasonal changes in aggression

1975 ◽  
Vol 53 (8) ◽  
pp. 1004-1011 ◽  
Author(s):  
Brian N. Turner ◽  
Michael R. Perrin ◽  
Stuart L. Iverson
Keyword(s):  
Microtus Pennsylvanicus ◽  
Meadow Vole ◽  
Breeding Period ◽  
Spruce Forest ◽  
Vole Population ◽  
Reproductive Condition ◽  
Interspecific Aggression ◽  
Meadow Voles ◽  
Nonbreeding Season ◽  
Short Period

Beginning in November 1973, numerous meadow voles (Microtus pennsylvanicus) moved onto a spruce forest grid occupied by red-backed voles (Clethrionomys gapperi). A resident meadow vole population resulted, the two species coexisting until April 1974, when most meadow voles disappeared from the grid during a relatively short period. Interspecific aggression levels, as determined from voles temporarily removed from the populations and tested in paired encounters in a laboratory arena, were low during the winter, but increased when males of both species entered reproductive condition in the spring. Microtus was generally dominant in early breeding period encounters, but this dominance declined concurrently with the meadow voles' disappearance from the forest. It is argued that meadow voles did not leave the forest to breed, or because the snow cover melted, since this species will live and reproduce in forest in the absence of Clethrionomys. The results are interpreted as support for an earlier hypothesis that competitive habitat exclusion varies seasonally with reproduction-related aggression. Thus, these species apparently may coexist in either of their preferred habitats when interspecific aggression is low (the nonbreeding season), but this relationship terminates when interspecific aggression levels increase with the resumption of breeding in the spring.

scholarly journals Spatially different annual cycles but similar haemosporidian infections in distant populations of collared sand martins

BMC Zoology ◽  
2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Steffen Hahn ◽  
Martins Briedis ◽  
Christos Barboutis ◽  
Raffaella Schmid ◽  
Martin Schulze ◽  
...  
Keyword(s):  
West Africa ◽  
Chronic Infection ◽  
Blood Parasite ◽  
Spring Migration ◽  
Lake Chad ◽  
Annual Cycles ◽  
Nonbreeding Season ◽  
Breeding Populations ◽  
High Parasitaemia ◽  
Western Palaearctic

Abstract Background Populations of long-distance migratory birds experience different environments and are consequently exposed to different parasites throughout their annual cycles. Though, specific whereabouts and accompanied host-parasite interactions remain unknown for most migratory passerines. Collared sand martins (Riparia riparia) breeding in the western Palaearctic spend the nonbreeding period in Africa, but it is not yet clear whether specific populations differ in overwintering locations and whether these also result in varying infections with vector-transmitted endoparasites. Results Geolocator tracking revealed that collared sand martins from northern-central and central-eastern Europe migrate to distant nonbreeding sites in West Africa and the Lake Chad basin in central Africa, respectively. While the ranges of these populations were clearly separated throughout the year, they consistently spent up to 60% of the annual cycle in Africa. Ambient light recorded by geolocators further indicated unsheltered roosting during the nonbreeding season in Africa compared to the breeding season in Europe. We found 5–26% prevalence of haemosporidian parasites in three breeding populations and one migratory passage population that was only sampled but not tracked. In total, we identified seven Plasmodium and nine Haemoproteus lineages (incl. two and seven new lineages, respectively), the latter presumably typical for swallows (Hirundinae) hosts. 99.5% of infections had a low intensity, typical for chronic infection stages, whereas three individuals (0.5%) showed high parasitaemia typical for acute infections during spring migration and breeding. Conclusions Our study shows that blood parasite infections are common in several western Palaearctic breeding populations of collared sand martins who spent the nonbreeding season in West Africa and the lake Chad region. Due to long residency at the nonbreeding grounds blood parasite transmissions may mainly occur at host population-specific residences sites in Europe and Africa; the latter being likely facilitated by unsheltered roosting and thus high vulnerability to hematophagous insects. The rare cases of high parasitaemia during spring migration and breeding further indicates either relapses of chronic infection or primary infections which occurred shortly before migration and during breeding.

Closure to “Aerial Surveys for Reservoir Planning”

1956 ◽  
Vol 121 (1) ◽  
pp. 519-520
Author(s):  
Francis J. Guscio
Keyword(s):  
Aerial Surveys ◽  
Reservoir Planning
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