scholarly journals Hooded Grebe Podiceps gallardoi population decreased by eighty per cent in the last twenty-five years

2012 ◽  
Vol 22 (4) ◽  
pp. 371-382 ◽  
Author(s):  
IGNACIO ROESLER ◽  
SANTIAGO IMBERTI ◽  
HERNÁN CASAÑAS ◽  
BETTINA MAHLER ◽  
JUAN CARLOS REBOREDA
Keyword(s):  
Population Size ◽  
Breeding Season ◽  
Low Temperatures ◽  
Buenos Aires ◽  
American Mink ◽  
Santa Cruz ◽  
Southern Patagonia ◽  
Conservation Actions ◽  
Strong Winds ◽  
Breeding Seasons

SummaryWe estimated the present population size of the Hooded Grebe Podiceps gallardoi and compared it with the population in 1985. During the breeding seasons 2009/2010 and 2010/2011 we monitored 251 lakes on the main plateaus of Santa Cruz province, southern Patagonia, Argentina, where the entire population of Hooded Grebes spends the breeding season. During 2009/2010 we monitored 131 lakes and observed 521 Hooded Grebes in 16 lakes, while during 2010/2011 we monitored 186 lakes and observed 535 individuals in 14 lakes. At both breeding seasons five lakes contained near 85% of the population. We only observed 6 breeding colonies, two in 2009/2010 and four in 2010/2011, totalling 242 nesting attempts. Nearly 90% of the nests failed during egg stage, mainly due to strong winds and depredation by American mink Neovison vison. Only 28 nests hatched chicks, but none of the young survived to independence due to low temperatures. We compared the results of our 2010/2011 survey with one conducted during 1984/1985 and detected that the population diminished by approximately 80%. This decline was observed on all but one plateau (“Buenos Aires”) where most breeding attempts occurred. Our results show that at present Hooded Grebes are highly dependent on a few suitable lakes where they congregate to breed. We analyse possible causes for the decline of the population and propose conservation actions to protect this species.

Clemente Onelli's sketch map and his first-hand, retrospective account of an early fossil-hunting expedition along the Río Santa Cruz, southern Patagonia, 1888–1889

2014 ◽  
Vol 41 (2) ◽  
pp. 326-337 ◽  
Author(s):  
P. D. Brinkman ◽  
S. F. Vizcaíno
Keyword(s):  
South America ◽  
North American ◽  
Buenos Aires ◽  
Santa Cruz ◽  
Field Museum ◽  
La Plata ◽  
Fossil Mammals ◽  
Southern Patagonia ◽  
Retrospective Account ◽  
Sketch Map

A 1922 letter from Clemente Onelli to North American paleontologist Elmer S. Riggs, found at Chicago's Field Museum, is one of only a few known first-hand accounts of the former's participation on a fossil hunting expedition along the Río Santa Cruz, southern Patagonia, 1888–1889. Onelli and his companions, who were sent to Patagonia by Francisco P. Moreno, director of the Museo de La Plata, were among the first to collect fossil mammals at this important locality. Moreno had first discovered fossil mammals there in 1876–1877. He then sent Carlos Ameghino, who worked as an assistant preparator of palaeontology at the museum, to revisit his discoveries in January 1887. Ameghino later lost his position at the museum over a dispute between his brother, paleontologist Florentino Ameghino, and the director, in March 1889. Onelli, who had only been associated with the Museo de La Plata for a few short months, was asked by Moreno to accompany a new expedition outfitted in 1888–1889. In December 1922, Riggs travelled to South America to make a representative collection of the fossil mammals of Argentina and Bolivia. Learning of his arrival in Buenos Aires, Onelli wrote him a letter, in Spanish, providing detailed information about fossil localities along the Río Santa Cruz. This letter, translated here, along with the accompanying sketch map, provides previously unknown details about Onelli's itinerary and his observations.

scholarly journals Evidence for use of both capital and income breeding strategies in the mangrove tree crab, Aratus pisonii

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jade Carver ◽  
Morgan Meidell ◽  
Zachary J. Cannizzo ◽  
Blaine D. Griffen
Keyword(s):  
Breeding Season ◽  
Breeding Strategy ◽  
Reproductive Period ◽  
Breeding Strategies ◽  
Mangrove Tree ◽  
Income Breeding ◽  
Aratus Pisonii ◽  
Breeding Seasons ◽  
And Storage ◽  
Capital And Income Breeding

AbstractTwo common strategies organisms use to finance reproduction are capital breeding (using energy stored prior to reproduction) and income breeding (using energy gathered during the reproductive period). Understanding which of these two strategies a species uses can help in predicting its population dynamics and how it will respond to environmental change. Brachyuran crabs have historically been considered capital breeders as a group, but recent evidence has challenged this assumption. Here, we focus on the mangrove tree crab, Aratus pisonii, and examine its breeding strategy on the Atlantic Florida coast. We collected crabs during and after their breeding season (March–October) and dissected them to discern how energy was stored and utilized for reproduction. We found patterns of reproduction and energy storage that are consistent with both the use of stored energy (capital) and energy acquired (income) during the breeding season. We also found that energy acquisition and storage patterns that supported reproduction were influenced by unequal tidal patterns associated with the syzygy tide inequality cycle. Contrary to previous assumptions for crabs, we suggest that species of crab that produce multiple clutches of eggs during long breeding seasons (many tropical and subtropical species) may commonly use income breeding strategies.

Rainfall in prior breeding seasons influences population size of a small marsupial

2012 ◽  
Vol 38 (5) ◽  
pp. 581-591 ◽  
Author(s):  
HANIA LADA ◽  
JAMES R. THOMSON ◽  
SHAUN C. CUNNINGHAM ◽  
RALPH MAC NALLY
Keyword(s):  
Population Size ◽  
Breeding Seasons

scholarly journals Density and Flock Size of the Raven (Corvus corax) In the Orawa - Nowy Targ Basin During Non-Breeding Season

Ring ◽  
2006 ◽  
Vol 28 (2) ◽  
pp. 119-125
Author(s):  
Michał Ciach ◽  
Dominik Wikar ◽  
Małgorzata Bylicka
Keyword(s):  
Breeding Season ◽  
Early Spring ◽  
Food Resources ◽  
High Density ◽  
Line Transect ◽  
Flock Size ◽  
Early Winter ◽  
Corvus Corax ◽  
Line Transect Method ◽  
Breeding Seasons

Density and Flock Size of the Raven (Corvus corax) In the Orawa - Nowy Targ Basin During Non-Breeding Season During the 2002/2003-2004/2005 non-breeding seasons the density of the Raven in the open habitats of the Orawa - Nowy Targ Basin was studied by line transect method. The results were analysed in four periods (autumn, early winter, winter and early spring). The median density of Ravens did not differ significantly between individual periods and was respectively: 3.5, 3.8, 4.8 and 3.8 indiv. / 10 km. Number of birds during particular controls varied from 1.0 to 24.8 indiv. / 10 km. However, while excluding flocks, the median density of single individuals and pairs of the Raven was considerably lower and in subsequent periods reached respectively: 2.2, 2.4, 2.2 and 1.7 indiv. / 10 km. Flock size did not differ significantly between individual periods. Single individuals and, less often, groups of two birds were recorded mostly. Small (3-5 indiv.) and medium (6-15 indiv.) flocks were recorded rarely and large flocks (16 indiv. and above) - only exceptionally. The high density and strong fluctuations of abundance of Ravens were determined by flocks presence, which was probably linked to irregular occurrence of food resources.

scholarly journals NOTES ON THE ECOLOGY OF THE COLOMBIAN LEAFTOED GECKO (PHYLLODACTYLUS TRANSVERSALIS), ENDEMIC TO MALPELO ISLAND

2016 ◽  
Vol 42 (2) ◽  
Author(s):  
Mateo López Victoria ◽  
Matthias Jurczyk ◽  
Volkmar Wolters
Keyword(s):  
Population Size ◽  
Breeding Season ◽  
Habitat Preference ◽  
Habitat Preferences ◽  
Original Description ◽  
Tropical Pacific ◽  
Reference Points ◽  
Eastern Tropical Pacific ◽  
Reptile Species ◽  
Malpelo Island

The Colombian leaf-toed gecko (Phyllodactylus transversalis) is the least known reptile species of Malpelo Island (Eastern Tropical Pacific). In the 37 years since its original description, no single study strictly dedicated to this species has been conducted. With the goal of providing information on the ecology and population size of this gecko, data collected during two visits to the island are presented. Behavior and reproduction were studied by following individuals during the night and by searching for hidden individuals and eggs during the day. Population’s density and habitat preferences were estimated by classifying the island’s surfaces into four types and counting geckos inside those habitats within band transects. General morphological measurements of geckos were performed as reference points for future comparisons. Phyllodactylus transversalis lays its eggs in narrow crevices of rocks, apparently communally. Reproduction seems to take place during most of the year, probably associated with the peak breeding season of seabirds. Although conspecifics shared shelters during the day, densities during the night suggest no apparent habitat preference for foraging. Population size of this species was estimated at approximately 114000 individuals.

Phenotypic plasticity of the montane vole (Microtus montanus) in unpredictable environments

1992 ◽  
Vol 70 (11) ◽  
pp. 2121-2124 ◽  
Author(s):  
Norman C. Negus ◽  
Patricia J. Berger ◽  
Aelita J. Pinter
Keyword(s):  
Phenotypic Plasticity ◽  
Breeding Season ◽  
Growth Rates ◽  
Adaptive Strategy ◽  
Severe Drought ◽  
Microtus Montanus ◽  
Age Cohort ◽  
Montane Meadow ◽  
Study Sites ◽  
Breeding Seasons

From 1987 to 1989, the cohort dynamics of Microtus montanus populations were studied at two montane meadow sites approximately 160 km apart, in northwestern Wyoming. The 1987 and 1988 breeding seasons differed markedly from each other. In 1987, melt off occurred in April, and the first cohort was born in May (cohort 1). The entire breeding season was favorable owing to frequent rainfall throughout the summer. Cohort 1 animals grew rapidly and females began breeding at 4–5 weeks of age. Likewise, cohort 2 (June) animals exhibited rapid growth and females were breeding at 7–8 weeks of age. Cohort 3 (July and August) animals grew more slowly and most entered the winter as prepubertal animals of subadult size. At the end of the summer, cohort 3 animals represented >70% of the voles recruited during the breeding season. In 1988, following melt off in late April, precipitation was below normal and the situation intensified to severe drought through the summer. The growth rates of cohort 1 and 2 animals were significantly lower than 1987 growth rates, and very few females attained sexual maturity. At the end of the summer, cohort 3 animals represented <25% of the total recruitment at both study sites. Such apparent phenotypic plasticity of growth and maturation appears to be an evolved adaptive strategy that is responsive to several environmental cues. Both study sites, although widely separated, exhibited virtually identical patterns throughout the study.

Flexibility of nuptial colouration in a unique ecotype of Threespine Stickleback (Gasterosteus aculeatus)

2021 ◽  
Author(s):  
Rachel Corney ◽  
Anne Haley ◽  
Laura Weir
Keyword(s):  
Breeding Season ◽  
Gasterosteus Aculeatus ◽  
Colour Change ◽  
Threespine Stickleback ◽  
Relative Role ◽  
Mate Quality ◽  
Breeding Seasons ◽  
Potential Signal ◽  
Intersexual Competition

Nuptial colouration in animals may serve as a signal of competitor and/or mate quality during breeding. In many temperate fishes, nuptial colouration develops during discrete breeding seasons and is a target of sexual selection. We examine nuptial colouration and behaviour of a unique ecotype of Threespine Stickleback (Gasterosteus aculeatus Linnaeus, 1758), wherein males turn from dull brown-grey to pearlescent white during the breeding season. The main goal of this work was to determine the relative role of white colouration in intersexual competition and mate choice. In a combination of a field and laboratory work, we found that males are brightest white when engaging in courtship activities in the presence of a female; this indicates that white colouration may be primarily related to enhancing signalling during mate attraction. White colouration intensity increased as the breeding season progressed and may be related to an influx of conspecifics. Colour change from cryptic grey to bright white occurred rapidly (< 90 seconds) and may be deployed to enhance behavioural signals. We conclude that bright white colouration in the white ecotype is a potential signal of mate quality and may have evolved from a previously existing capacity for colour plasticity in common Threespine Stickleback.

A new Gripopterygidae (Plecoptera) species from southern Patagonia

Zootaxa ◽  
2009 ◽  
Vol 2264 (1) ◽  
pp. 51-57 ◽  
Author(s):  
PABLO PESSACQ
Keyword(s):  
Instar Larva ◽  
Santa Cruz ◽  
Argentinean Patagonia ◽  
Southern Patagonia

The male, female, and last instar larva of Andiperlodes tehuelche n. sp., an apterous species of Gripopterygidae, are described from the Santa Cruz Province, Argentinean Patagonia.

scholarly journals 215SUCCESSFUL OUT-OF-BREEDING SEASON ESTRUS SYNCHRONIZATION FOLLOWED BY FIXED TIME INSEMINATION IN WATERBUFFALO (BUBALUS BUBALIS)

2004 ◽  
Vol 16 (2) ◽  
pp. 229 ◽  
Author(s):  
R.M. Züge ◽  
U. Rodacki ◽  
A.T. Grandi ◽  
J.M.J. Aerts ◽  
P.E.J. Bols
Keyword(s):  
Breeding Season ◽  
Buenos Aires ◽  
Fixed Time ◽  
Estradiol Benzoate ◽  
Sao Paulo ◽  
Reproductive Efficiency ◽  
São Paulo ◽  
Estrus Synchronization ◽  
The Impact ◽  
Synchronization Protocol

The most important barrier to the increase of buffalo productivity is an overall poor reproductive efficiency, characterized by late sexual maturity, seasonal anestrus and long periods of postpartum ovarian inactivity resulting in extended calving intervals and poor expression of estrus behavior (Singh J et al., 2000, Anim. Reprod. Sci. 60–61, 593–604). Buffaloes are seasonal breeders with the highest reproductive activities during winter (short day lengths) and a high frequency of anestrus during the summer months (Singh G et al. 1985, Ind. J. Anim. Res. 19, 57–60). Recent research demonstrated that a combination of progesterone, estradiol benzoate and equine chorionic gonadotropin (eCG) was effective for estrus induction and synchronization in buffalo heifers under Mediterranean conditions (Barile et al. 2001, Livestock Prod. Sci. 68, 283–287). The aim of the present study was to investigate the impact of an estrus synchronization protocol on reproductive efficiency of water buffalo during out of the normal breeding season. A total of six heifers (21 to 23 months of age) and three cows (5, 6 and 18 years of age) were enrolled in an estrus synchronization protocol lasting for 12 days. All animals were kept under tropical conditions in the coastal part of Paraná (Antonina), about 450km south of São Paulo. The experiment was performed in December, 2002, during the Brazilian summer season, when reproductive efficiency of buffaloes is greatly reduced. On the first day of the protocol (Day 0), animals were implanted with an intravaginal device containing 1g of progesterone (DIB, Syntex SA, Buenos Aires, Argentina) and injected with 10mg estradiol benzoate (Estrogin, Famavet, São Paulo, Brazil). On Day 9, the DIB implant was removed and the animals received 150μg (i.m.) of cloprostenol (Prolise, Syntex SA, Buenos Aires, Argentina) and 2500 IU of eCG (Novormon, Syntex SA, Buenos Aires, Argentina). On Day 11, all animals received 1500 IU of hCG (Vetecor, Lab. Calier, Spain). Artificial insemination (AI) was performed on Day 12 using frozen-thawed semen from a bull of proven fertility. Only one AI was performed per heifer/cow. Pregnancies were determined by ultrasound examination at 53 days following AI and confirmed by rectal palpation at 90 days post AI. The use of this estrus synchronization protocol, followed by fixed-time insemination, resulted in four pregnant heifers (66%) and three pregnant cows (100%). Our results demonstrate that buffalo reproduction can be successful during out-of-breeding season when adequate hormonal treatment is used. Additional experiments should be done to validate the protocol.

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