scholarly journals Diet Drives Differences in Reproductive Synchrony in Two Sympatric Mountain Ungulates in the Himalaya

2021 ◽  
Vol 9 ◽  
Author(s):  
Tanushree Srivastava ◽  
Ajith Kumar ◽  
Vinod Kumar ◽  
Govindhaswamy Umapathy
Keyword(s):  
Diet Quality ◽  
Seasonal Variations ◽  
Vegetation Index ◽  
Resource Competition ◽  
Physiological Stress ◽  
Sympatric Species ◽  
Plant Phenology ◽  
Musk Deer ◽  
Reproductive Synchrony ◽  
Diet Type

Ungulates in higher latitudes and altitudes experience sharp seasonal changes in forage abundance and quality. In response, ungulates show varying degrees of synchrony in reproduction. Diet type has been hypothesized to be a determinant of differences in reproductive synchrony. Analyses at global scales using proxies of plant phenology such as climate, latitude and Normalized Difference Vegetation Index (NDVI) have found no evidence in support because such proxies do not capture differences in phenology among plant taxa at local scales. We compared seasonal variations in diet quality with reproductive synchrony in the Himalayan musk deer (Moschus chrysogaster), a browser, and the Himalayan goral (Naemorhedus goral), a grazer, in mid-altitude Himalaya. We also compared seasonal variations in physiological stress using fecal glucocorticoid metabolite (FGM). We identified different stages of female reproductive cycle using fecal concentrations of metabolites of estradiol, pregnanediol-3-glucuronide (PdG) and testosterone and used fecal crude protein (CP) as an indicator of diet quality. In musk deer, fecal estradiol and PdG concentrations showed a dispersed estrous and parturition, respectively. Goral had a more synchronized estrous and parturition. Estrous cycles in both species occurred when diet quality was poor, but parturition occurred when diet quality was high. Greater seasonality in reproduction in goral is driven by sharp phenological changes in graminoids on which it feeds, compared to slow changes in browse on which musk deer feeds. Thus, we show that diet type drives the differences in reproductive synchrony in these two sympatric species. Spring and summer with highest diet quality were times of highest stress in both the ungulates. We hypothesize predation pressure from feral dogs and resource competition with livestock as plausible explanations for this, which need to be tested in future. Our findings also highlight the need for studying relationships among plant phenology, diet type and reproductive biology of ungulates at local scales if we are to understand species responses to global phenomena such as climate change.

scholarly journals Coexistence of three sympatric cormorants ( Phalacrocorax spp.); partitioning of time as an ecological resource

2016 ◽  
Vol 3 (5) ◽  
pp. 160175 ◽  
Author(s):  
Mylswamy Mahendiran
Keyword(s):  
Resource Partitioning ◽  
Resource Competition ◽  
Physiological Stress ◽  
Sympatric Species ◽  
Freshwater Wetlands ◽  
Foraging Habitat ◽  
Phalacrocorax Carbo ◽  
Late Afternoon ◽  
Temporal Partitioning ◽  
Foraging Time

Resource partitioning is well known along food and habitat for reducing competition among sympatric species, yet a study on temporal partitioning as a viable basis for reducing resource competition is not empirically investigated. Here, I attempt to identify the mechanism of temporal partitioning by intra- and interspecific diving analyses of three sympatric cormorant species at different freshwater wetlands around the Delhi region. Diving results indicated that cormorants opted for a shallow diving; consequently, they did not face any physiological stress. Moreover, diving durations were linked with seasons, foraging time and foraging habitats. Intraspecific comparison suggested that cormorants spent a longer time underwater in early hours of the day. Therefore, time spent for dive was higher in the forenoon than late afternoon, and the interspecific analysis also yielded a similar result. When Phalacrocorax niger and Phalacrocorax fuscicollis shared the same foraging habitat, they tended to differ in their foraging time (forenoon/afternoon). However, when P. niger and Phalacrocorax carbo shared the same foraging time, they tended to use different foraging habitats (lentic/lotic) leading to a mechanism of resource partitioning. Thus, sympatric cormorants effectively use time as a resource to exploit the food resources and successful coexistence.

scholarly journals Using Near-Infrared-Enabled Digital Repeat Photography to Track Structural and Physiological Phenology in Mediterranean Tree–Grass Ecosystems

2018 ◽  
Vol 10 (8) ◽  
pp. 1293 ◽  
Author(s):  
Yunpeng Luo ◽  
Tarek S. El-Madany ◽  
Gianluca Filippa ◽  
Xuanlong Ma ◽  
Bernhard Ahrens ◽  
...  
Keyword(s):  
Vegetation Index ◽  
Near Infrared ◽  
Normalized Difference Vegetation Index ◽  
Growing Season ◽  
Plant Phenology ◽  
Mediterranean Ecosystem ◽  
Near Infrared Reflectance ◽  
Seasonally Dry ◽  
Growing Season Length ◽  
Dry Down

Tree–grass ecosystems are widely distributed. However, their phenology has not yet been fully characterized. The technique of repeated digital photographs for plant phenology monitoring (hereafter referred as PhenoCam) provide opportunities for long-term monitoring of plant phenology, and extracting phenological transition dates (PTDs, e.g., start of the growing season). Here, we aim to evaluate the utility of near-infrared-enabled PhenoCam for monitoring the phenology of structure (i.e., greenness) and physiology (i.e., gross primary productivity—GPP) at four tree–grass Mediterranean sites. We computed four vegetation indexes (VIs) from PhenoCams: (1) green chromatic coordinates (GCC), (2) normalized difference vegetation index (CamNDVI), (3) near-infrared reflectance of vegetation index (CamNIRv), and (4) ratio vegetation index (CamRVI). GPP is derived from eddy covariance flux tower measurement. Then, we extracted PTDs and their uncertainty from different VIs and GPP. The consistency between structural (VIs) and physiological (GPP) phenology was then evaluated. CamNIRv is best at representing the PTDs of GPP during the Green-up period, while CamNDVI is best during the Dry-down period. Moreover, CamNIRv outperforms the other VIs in tracking growing season length of GPP. In summary, the results show it is promising to track structural and physiology phenology of seasonally dry Mediterranean ecosystem using near-infrared-enabled PhenoCam. We suggest using multiple VIs to better represent the variation of GPP.

scholarly journals Comparison of Landsat and Land-Based Phenology Camera Normalized Difference Vegetation Index (NDVI) for Dominant Plant Communities in the Great Basin

Sensors ◽  
2019 ◽  
Vol 19 (5) ◽  
pp. 1139 ◽  
Author(s):  
Keirith Snyder ◽  
Justin Huntington ◽  
Bryce Wehan ◽  
Charles Morton ◽  
Tamzen Stringham
Keyword(s):  
Great Basin ◽  
Plant Communities ◽  
Spatial Resolution ◽  
Temporal Resolution ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Spatial Scales ◽  
Plant Phenology ◽  
High Temporal Resolution ◽  
Spatial Coverage

Phenology of plants is important for ecological interactions. The timing and development of green leaves, plant maturity, and senescence affects biophysical interactions of plants with the environment. In this study we explored the agreement between land-based camera and satellite-based phenology metrics to quantify plant phenology and phenophases dates in five plant community types characteristic of the semi-arid cold desert region of the Great Basin. Three years of data were analyzed. We calculated the Normalized Difference Vegetation Index (NDVI) for both land-based cameras (i.e., phenocams) and Landsat imagery. NDVI from camera images was calculated by taking a standard RGB (red, green, and blue) image and then a near infrared (NIR) plus RGB image. Phenocam NDVI was calculated by extracting the red digital number (DN) and the NIR DN from images taken a few seconds apart. Landsat has a spatial resolution of 30 m2, while phenocam spatial resolution can be analyzed at the single pixel level at the scale of cm2 or area averaged regions can be analyzed with scales up to 1 km2. For this study, phenocam regions of interest were used that approximated the scale of at least one Landsat pixel. In the tall-statured pinyon and juniper woodland sites, there was a lack of agreement in NDVI between phenocam and Landsat NDVI, even after using National Agricultural Imagery Program (NAIP) imagery to account for fractional coverage of pinyon and juniper versus interspace in the phenocam data. Landsat NDVI appeared to be dominated by the signal from the interspace and was insensitive to subtle changes in the pinyon and juniper tree canopy. However, for short-statured sagebrush shrub and meadow communities, there was good agreement between the phenocam and Landsat NDVI as reflected in high Pearson’s correlation coefficients (r > 0.75). Due to greater temporal resolution of the phenocams with images taken daily, versus the 16-day return interval of Landsat, phenocam data provided more utility in determining important phenophase dates: start of season, peak of season, and end of season. More specific species-level information can be obtained with the high temporal resolution of phenocams, but only for a limited number of sites, while Landsat can provide the multi-decadal history and spatial coverage that is unmatched by other platforms. The agreement between Landsat and phenocam NDVI for short-statured plant communities of the Great Basin, shows promise for monitoring landscape and regional-level plant phenology across large areas and time periods, with phenocams providing a more comprehensive understanding of plant phenology at finer spatial scales, and Landsat extending the historical record of observations.

A semi-analytical snow-free vegetation index for improving estimation of plant phenology in tundra and grassland ecosystems

2019 ◽  
Vol 228 ◽  
pp. 31-44 ◽  
Author(s):  
Wei Yang ◽  
Hideki Kobayashi ◽  
Cong Wang ◽  
Miaogen Shen ◽  
Jin Chen ◽  
...  
Keyword(s):  
Vegetation Index ◽  
Plant Phenology ◽  
Grassland Ecosystems

Association between physiological stress load and diet quality patterns differs between male and female adults

2021 ◽  
pp. 113538
Author(s):  
Sarah M. Dimitratos ◽  
Melanie Hercules ◽  
Charles B Stephensen ◽  
Eduardo Cervantes ◽  
Kevin D Laugero
Keyword(s):  
Diet Quality ◽  
Physiological Stress ◽  
Male And Female ◽  
Stress Load

Effects of diet quality on growth pattern, serum oxidative status, and corticosterone in Pigeons (Columba livia)

2010 ◽  
Vol 88 (8) ◽  
pp. 795-802 ◽  
Author(s):  
David Costantini
Keyword(s):  
Antioxidant Capacity ◽  
Diet Quality ◽  
Growth Pattern ◽  
Physiological Stress ◽  
Columba Livia ◽  
Oxidative Status ◽  
Developmental Period ◽  
Serum Corticosterone ◽  
Nutritional Deprivation ◽  
Quality Diet

Oxidative stress has been suggested to be affected by the growth and developmental period of animals, hence it may play an important role in the trade-off between growth and self-maintenance. In this study, I analysed the effects of two different diet regimes (high-quality diet, HQD; low-quality diet, LQD) on growth pattern, three components of the serum oxidative status (hydroperoxides, antioxidant capacity, and thiols), and serum corticosterone in nestling Pigeons ( Columba livia Gmelin, 1789). The growth pattern was similar in the first week of life, after which HQD nestlings grew faster than LQD nestlings. Although there were no differences in serum corticosterone or thiol concentrations, serum oxidative damage increased faster over the nestling phase in HQD than LQD chicks. Serum antioxidant capacity remained stable over time in LQD nestlings and increased in HQD nestlings. This study provides evidence that different growth rates (induced in the absence of any physiological stress or prior nutritional deprivation) are accompanied by different serum oxidative statuses.

scholarly journals Functional analysis of Normalized Difference Vegetation Index curves reveals overwinter mule deer survival is driven by both spring and autumn phenology

2014 ◽  
Vol 369 (1643) ◽  
pp. 20130196 ◽  
Author(s):  
Mark A. Hurley ◽  
Mark Hebblewhite ◽  
Jean-Michel Gaillard ◽  
Stéphane Dray ◽  
Kyle A. Taylor ◽  
...  
Keyword(s):  
Functional Analysis ◽  
Body Mass ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Mule Deer ◽  
Plant Phenology ◽  
Spring Phenology ◽  
Overwinter Survival ◽  
Wide Range ◽  
Functional Components

Large herbivore populations respond strongly to remotely sensed measures of primary productivity. Whereas most studies in seasonal environments have focused on the effects of spring plant phenology on juvenile survival, recent studies demonstrated that autumn nutrition also plays a crucial role. We tested for both direct and indirect (through body mass) effects of spring and autumn phenology on winter survival of 2315 mule deer fawns across a wide range of environmental conditions in Idaho, USA. We first performed a functional analysis that identified spring and autumn as the key periods for structuring the among-population and among-year variation of primary production (approximated from 1 km Advanced Very High Resolution Radiometer Normalized Difference Vegetation Index (NDVI)) along the growing season. A path analysis showed that early winter precipitation and direct and indirect effects of spring and autumn NDVI functional components accounted for 45% of observed variation in overwinter survival. The effect size of autumn phenology on body mass was about twice that of spring phenology, while direct effects of phenology on survival were similar between spring and autumn. We demonstrate that the effects of plant phenology vary across ecosystems, and that in semi-arid systems, autumn may be more important than spring for overwinter survival.

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