scholarly journals Intra-tropical movements as a beneficial strategy for Palearctic migratory birds

2018 ◽  
Vol 5 (1) ◽  
pp. 171675 ◽  
Author(s):  
Jaroslav Koleček ◽  
Steffen Hahn ◽  
Tamara Emmenegger ◽  
Petr Procházka
Keyword(s):  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Migratory Birds ◽  
Breeding Site ◽  
Breeding Population ◽  
Acrocephalus Arundinaceus ◽  
Insectivorous Birds ◽  
Mean Values ◽  
Breeding Sites ◽  
Breeding Range

Migratory birds often move significantly within their non-breeding range before returning to breed. It remains unresolved under which circumstances individuals relocate, whether movement patterns are consistent between populations and to what degree the individuals benefit from the intra-tropical movement (ITM). We tracked adult great reed warblers Acrocephalus arundinaceus from a central and a southeastern European breeding population, which either stay at a single non-breeding site, or show ITM, i.e. move to a second site. We related ITM to the normalized difference vegetation index (NDVI) describing vegetation conditions and probably reflecting food abundance for these insectivorous birds. Three-quarters of birds showed ITM across the non-breeding range. We found no difference in range values and mean values of NDVI between the single non-breeding sites of stationary birds and the two sites of moving birds. The vegetation conditions were better at the second sites compared to the first sites during the period which moving birds spent at the first sites. Vegetation conditions further deteriorated at the first sites during the period the moving birds resided at their second sites. Our study provides evidence that birds probably benefit from improved conditions after ITM compared to the conditions at the sites from where they departed.

scholarly journals Hydrological model parameterization using NDVI values to account for the effects of land cover change on the rainfall–runoff response

2017 ◽  
Vol 48 (6) ◽  
pp. 1455-1473 ◽  
Author(s):  
Vahid Nourani ◽  
Ahmad Fakheri Fard ◽  
Hoshin V. Gupta ◽  
David C. Goodrich ◽  
Faegheh Niazi
Keyword(s):  
Land Cover ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Remote Sensing Data ◽  
Model Parameters ◽  
Rainfall Runoff ◽  
Remotely Sensed Data ◽  
Efficiency Criterion ◽  
Mean Values ◽  
Model Parameter

Abstract Classic rainfall–runoff models usually use historical data to estimate model parameters and mean values of parameters are considered for predictions. However, due to climate changes and human effects, model parameters change temporally. To overcome this problem, normalized difference vegetation index (NDVI) derived from remotely sensed data was used in this study to investigate the effect of land cover variations on hydrological response of watersheds using a conceptual rainfall–runoff model. The study area consists of two sub-watersheds (Hervi and Lighvan) with varied land cover conditions. Obtained results show that the one-parameter model generates runoff forecasts with acceptable level of the considered criteria. Remote sensing data were employed to relate land cover properties of the watershed to the model parameter. While a power form of the regression equation could be best fitted to the parameter values using available images of Hervi sub-watershed, for the Lighvan sub-watershed the fitted equation shows somewhat lower correlation due to higher fluctuations of the model parameter. The average values of the Nash–Sutcliffe efficiency criterion of the model were obtained as 0.87 and 0.55, respectively, for Hervi and Lighvan sub-watersheds. Applying this methodology, the model's parameters might be determined using temporal NDVI values.

scholarly journals Spectral signature of brown rust and orange rust in sugarcane

2020 ◽  
pp. 9-20
Author(s):  
Eniel Rodríguez-Machado ◽  
Osmany Aday-Díaz ◽  
Luis Hernández-Santana ◽  
Jorge Luís Soca-Muñoz ◽  
Rubén Orozco-Morales
Keyword(s):  
Precision Agriculture ◽  
Spectral Reflectance ◽  
Vegetation Index ◽  
Near Infrared ◽  
Normalized Difference Vegetation Index ◽  
Brown Rust ◽  
Spectral Signature ◽  
Spatial And Temporal Variability ◽  
Mean Values ◽  
Index Value

Precision agriculture, making use of the spatial and temporal variability of cultivable land, allows farmers to refine fertilization, control field irrigation, estimate planting productivity, and detect pests and disease in crops. To that end, this paper identifies the spectral reflectance signature of brown rust (Puccinia melanocephala) and orange rust (Puccinia kuehnii), which contaminate sugar cane leaves (Saccharum spp.). By means of spectrometry, the mean values and standard deviations of the spectral reflectance signature are obtained for five levels of contamination of the leaves in each type of rust, observing the greatest differences between healthy and diseased leaves in the red (R) and near infrared (NIR) bands. With the results obtained, a multispectral camera was used to obtain images of the leaves and calculate the Normalized Difference Vegetation Index (NDVI). The results identified the presence of both plagues by differentiating healthy from contaminated leaves through the index value with an average difference of 11.9% for brown rust and 9.9% for orange rust.

Female Choice and Male Courtship Behaviour in the Beaugregory Damselfish

Behaviour ◽  
2004 ◽  
Vol 141 (4) ◽  
pp. 391-405 ◽  
Author(s):  
◽  
◽  
Keyword(s):  
Reproductive Success ◽  
Female Choice ◽  
Individual Variation ◽  
Early Stage ◽  
Breeding Site ◽  
Male Courtship ◽  
Egg Survival ◽  
Mean Values ◽  
Breeding Sites ◽  
Experimental Group

AbstractDuring courtship in the beaugregory (Stegastes leucostictus), a coral reef fish, males turn the dorsal half of their bodies from dull brown to bright yellow, and perform a series of rapid dipping movements in front of females. To look for evidence that females select males on the basis of these characteristics, we provided males with artificial breeding sites in the field, measured their reproductive success, and videotaped courtship. Reproductive success was measured by monitoring both the number and size of egg clutches present in the breeding site that was defended by the male. Both unmanipulated and experimentally induced courtship events were videotaped in separate groups of 88 (of which 32 were videotaped courting females) and 30 males, respectively. Experimental induction of courtship was done by placing a female in a clear plastic cylinder 0.5 m away from the breeding site of a territorial male; each of the 30 males received 8 different female presentations, but never more than one a day, and with a different female every time. We compared (i) the cumulative amount of eggs and number of clutches with the amount of yellow colouration and dipping rate for individual males in both the observational and experimental groups, (ii) individual variation in percentage yellow and dipping rate (for the experimental group only) with reproductive success on the same day when courtship was videotaped, and (iii) egg survivorship (ratio of final to early stage eggs) with yellow colouration and dipping rate, to see if these characteristics indicate male parental ability. Individual variation in courtship characteristics was not correlated with reproductive success on that day. In contrast, however, mean values of percentage yellow and dip rate were correlated with both the number of clutches and amount of eggs, for both the observational and experimental group of males, indicating that females preferentially spawn with males that have the brightest yellow colouration and the highest dip rate. Percentage yellow colouration was correlated with egg survival in the unmanipulated males, but not in the experimental group, while dipping rate was not correlated with egg survival in either group. We argue here that female assessment of male courtship is part of a complex process of female choice, in which females either simultaneously or sequentially examine territorial, breeding site, and male characteristics, and thereby attempt to enhance the survivorship of their offspring.

scholarly journals Vegetation indices in the prediction of biomass and grain yield of white oat under irrigation levels

2018 ◽  
Vol 48 (2) ◽  
pp. 109-117 ◽  
Author(s):  
Anderson Prates Coelho ◽  
David Luciano Rosalen ◽  
Rogério Teixeira de Faria
Keyword(s):  
Grain Yield ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Flag Leaf ◽  
Vegetation Indices ◽  
Leaf Sheath ◽  
Phenological Stage ◽  
Mean Values ◽  
Ripe Stage ◽  
Irrigation Levels

ABSTRACT Vegetation indices are widely used to indicate the nutritional status of crops, as well as to estimate their harvest yield. However, their accuracy is influenced by the phenological stage of evaluation and the index used. The present study aimed to evaluate the accuracy of the Normalized Difference Vegetation Index (NDVI) and Inverse Ratio Vegetation Index (IRVI) in the prediction of grain yield and biomass of white oat cultivated under irrigation levels, besides indicating the best phenological stage for evaluation. The irrigation levels consisted of 11 %, 31 %, 60 %, 87 % and 100 % of the maximum evapotranspiration, with four replicates. The mean values for NDVI and IRVI were determined using an active terrestrial sensor, at four phenological stages (4, 8, 10 and 10.5.4). The white oat grain yield and biomass may be estimated with a high precision using the NDVI and IRVI. The NDVI was more accurate than the IRVI. The grain yield estimate was more accurate from the flag leaf sheath appearance stage (10), whereas, for the biomass, the best estimate was for the kernel watery ripe stage (10.5.4).

Breeding behaviour and reproduction in the Pampa de Achala toad, Bufo achalensis

2005 ◽  
Vol 26 (4) ◽  
pp. 451-458 ◽  
Author(s):  
◽  
◽  
Keyword(s):  
Breeding Site ◽  
Reproductive Behaviour ◽  
Breeding Population ◽  
Male Reproductive Success ◽  
Breeding Sites ◽  
Size Dependent ◽  
Breeding Populations ◽  
Site Characteristics ◽  
Capture Recapture ◽  
First Time

AbstractDuring 1999 and 2000 the reproductive behaviour, breeding site characteristics and reproduction of Bufo achalensis were studied mainly at La Ciénaga stream, Pampa de Achala, Argentina, using capture-recapture and skeletochronology methods. Breeding activity occurred from mid-August to mid-September and was explosive. Males and females congregated at night at selected, but scarce, breeding sites, resulting in a patchy distribution of small breeding populations near to the stream source. The sex ratio (♂ : ♀) of the breeding population ranged between 0.65 : 1 and 1.16 : 1. On average, breeding males were larger and older than breeding females. Although most females and males reached sexual maturity at four and five years of age, some bred for the first time at the ages of three and four years respectively. Neither size dependent nor size assortative pairings were found. Male reproductive success was not related to body size (SVL) but was related to the number of nights spent at a breeding site. Females laid between 700-2,390 eggs. Eggs hatched approximately nine days after deposition and larval development was completed in about two months.

Nonbreeding season movements of a migratory songbird are related to declines in resource availability

The Auk ◽  
2019 ◽  
Vol 136 (3) ◽  
Author(s):  
Samantha M Knight ◽  
Elizabeth A Gow ◽  
David W Bradley ◽  
Robert G Clark ◽  
Marc Bélisle ◽  
...  
Keyword(s):  
Resource Availability ◽  
Large Scale ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Light Level ◽  
Tree Swallow ◽  
Breeding Sites ◽  
Nonbreeding Season ◽  
Aerial Insectivore ◽  
Migratory Songbird

Abstract There have been an increasing number of observations of itinerancy in migratory songbirds, where individuals move among 2 or more widely separated areas during the “stationary” nonbreeding season. Knowledge of such movements and an understanding of what drives them are important for predicting how migratory populations will respond to environmental change. In this study, we investigated nonbreeding movements of the Tree Swallow (Tachycineta bicolor), an aerial insectivore that breeds across North America and spends the nonbreeding season around the Gulf of Mexico, Florida, Mexico, Central America, and the Caribbean. With year-round tracking data obtained from 133 light-level geolocators deployed at 12 breeding sites ranging from Alaska to Nova Scotia to North Carolina, we show that 44% of individuals made at least one large-scale movement (range: 301–1,744 km) within the nonbreeding range. The frequency of itinerancy decreased with longitude, such that 75% of individuals made a movement in the western portion of the nonbreeding range compared to only 31% in the east. Using the Normalized Difference Vegetation Index (NDVI) as a proxy for resource availability, we found that when individuals did move, they were more likely to move from sites where resources were deteriorating faster (a more negative change in NDVI prior to departure) than their destination sites. There was also evidence that individuals moved to destination sites with higher NDVI and temperature in the autumn, but not in the winter. Our results suggest movements of Tree Swallows during the nonbreeding season are influenced by resource availability, but because not all individuals used multiple nonbreeding sites, the density of individuals at a site and the level of competition may have also been a factor influencing nonbreeding season movements.

scholarly journals Sex ratio of breeding Common toads (Bufo bufo) – influence of survival and skipped breeding

2010 ◽  
Vol 31 (4) ◽  
pp. 509-524 ◽  
Author(s):  
Thomas Madsen ◽  
Jon Loman
Keyword(s):  
Sex Ratio ◽  
Deterministic Model ◽  
Breeding Site ◽  
Breeding Population ◽  
Bufo Bufo ◽  
Adult Males ◽  
Breeding Sites ◽  
Lower Survival Rate ◽  
Biased Sex Ratio ◽  
Males And Females

AbstractAnuran sex ratio at breeding sites is typically male biased. Such sex ratios may be due to poor female survival, to females not breeding as frequently as males and/or to males becoming sexually mature earlier than females. In the present study, the first two factors are analyzed in a common toad (Bufo bufo) population in southern Sweden. Toads were captured, marked and recaptured at the breeding site during 5 years. Within season capture patterns were analyzed using the Jolly-Seber model and among-year captures using the Closed robust design model. Population estimates of males and females yielded an among year variation in breeding population sex ratio, ranging from 16% to 34% females. On average, 41% (proportion adult alive but not breeding) of the females skipped breeding seasons, whereas the corresponding estimate for males was less than 5%. Yearly survival averaged 42% for adult female and 63% for adult male toads. First year adult males and females had a lower survival rate than older toads. Our results demonstrate that both a female biased mortality rate and a higher proportion of skipped breeding in females contribute to the observed male biased sex ratio. However, a deterministic model suggests other factors may also be involved to obtain this degree of male biased sex ratio, the most likely being that females mature at a later age than male toads.

The potential breeding range of Slender-billed Curlew Numenius tenuirostris identified from stable-isotope analysis

2017 ◽  
Vol 28 (2) ◽  
pp. 228-237
Author(s):  
GRAEME M. BUCHANAN ◽  
ALEXANDER L. BOND ◽  
NICOLA J. CROCKFORD ◽  
JOHANNES KAMP ◽  
JAMES W. PEARCE-HIGGINS ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Western Siberia ◽  
Isotope Analysis ◽  
Breeding Population ◽  
Calibration Equation ◽  
Breeding Sites ◽  
Breeding Range ◽  
Nest Sites ◽  
Nesting Sites ◽  
Southern Russia

SummaryThe breeding areas of the Critically Endangered Slender-billed Curlew Numenius tenuirostris are all but unknown, with the only well-substantiated breeding records being from the Omsk province, western Siberia. The identification of any remaining breeding population is of the highest priority for the conservation of any remnant population. If it is extinct, the reliable identification of former breeding sites may help determine the causes of the species’ decline, in order to learn wider conservation lessons. We used stable isotope values in feather samples from juvenile Slender-billed Curlews to identify potential breeding areas. Modelled precipitation δ2H data were compared to feather samples of surrogate species from within the potential breeding range, to produce a calibration equation. Application of this calibration to samples from 35 Slender-billed Curlew museum skins suggested they could have originated from the steppes of northern Kazakhstan and part of southern Russia between 48°N and 56°N. The core of this area was around 50°N, some way to the south of the confirmed nesting sites in the forest steppes. Surveys for the species might be better targeted at the Kazakh steppes, rather than around the historically recognised nest sites of southern Russia which might have been atypical for the species. We consider whether agricultural expansion in this area may have contributed to declines of the Slender-billed Curlew population.

scholarly journals Environmental sensitivity to mosquito transmitted diseases in El-Fayoum using spatial analyses

2020 ◽  
Vol 167 ◽  
pp. 03002
Author(s):  
Asmaa M. El-Hefni ◽  
Ahmed M. El-Zeiny ◽  
Hala A. Effat
Keyword(s):  
Land Surface ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Malaria Vectors ◽  
Moisture Index ◽  
Risk Area ◽  
Gis Modeling ◽  
Breeding Sites ◽  
Mosquito Breeding ◽  
Fayoum Governorate

El-Fayoum governorate has unique characteristics which induces mosquito proliferation and thus increased the risk arisen from diseases transmission. Present study explores the role of remote sensing and GIS modeling integrated with field survey for mapping mosquito breeding sites and the areas under risk of diseases transmission in El-Fayoum governorate. Entomological surveys were conducted for a total number of 40 accessible breeding sites during the period 12-16 November 2017. A calibrated Landsat OLI image, synchronized with the field trip, was processed to produce Normalized Difference Vegetation Index (NDVI), Normalized Difference Moisture Index (NDMI), and Land Surface Temperature (LST). A cartographic GIS model was generated to predict breeding sites in the whole governorate and to assess the potential risk. The main filarial disease vector (Culex pipiens) was abundant at Atsa district, while Malaria vectors (Anopheles sergentii and Anopheles multicolor) were mainly distributed in El-Fayoum and Youssef El-Seddiq districts. Means levels of NDVI, NDMI and LST at breeding habitats were recorded; 0.18, 0.08 and 21.75° C, respectively. Results of the model showed that the highest predicted risk area was reported at Atsa district (94.4 km2) and Yousef El-Sediq (81.8 km2) while the lowest prediction was observed at Abshawai district (35.9 km2). It can be concluded that Atsa, Yousef El-Sedik and El-Fayoum districts are more vulnerable to Malaria and Filaria diseases outbreaks, thus precaution and pest control methods must be applied to mitigate the possible risks.

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