scholarly journals Population status of the American crocodile, Crocodylus acutus (Reptilia: Crocodylidae) and the spectacled caiman, Caiman crocodilus (Reptilia: Alligatoridae) in the Costa Rican North Caribbean

2021 ◽  
Vol 34 (2) ◽  
Author(s):  
Iván Sandoval Hernández ◽  
Juan José Sánchez Ramírez ◽  
Juan Rafael Bolaños Montero ◽  
Juan Salvador Monrós González
Keyword(s):  
National Park ◽  
Colorado River ◽  
Costa Rican ◽  
Population Status ◽  
North Central ◽  
Caiman Crocodilus ◽  
The North ◽  
Crocodylus Acutus ◽  
American Crocodile ◽  
Significant Difference

Along the Costa Rican Caribbean shoreline, it is possible to find two species of crocodilians, the American crocodile (Crocodylus acutus) and the spectacled caiman (Caiman crocodilus). This region can be divided geographically into three subregions: North, Central, and South Caribbean. We conducted this research in the North Caribbean, between October 6, 2018 and August 31, 2019. Specifically, we worked in the area lying between the Jalova Station of the Tortugero National Park (TNP) and Agua Dulce Lake situated in the northern tip of Machuca Island, at the mouth of the Colorado River inside the Barra del Colorado National Wildlife Refuge (BACORE), which includes other connecting wetlands as well (Sierpe River, Samay Lake). Overall, this study area had an approximate extension of 408 km2 characterized by large, wide and deep canals, as well as wetlands, meanders, and adjacent lakes. The sampling was performed along 10 segments that varied in length from 7.5 km up to 29.49 km, located in the nearby zones of TNP and BACORE. In these zones, nightly counts were carried out using dazzling lamps. Individuals of C. acutus and C. crocodilus were classified into eight and six body size classes, respectively (both with 50 cm intervals). A relative abundance of 0.55 crocodiles and 1.37 caimans per linear kilometer was estimated during these spotlight surveys. The capture of 39 caimans let us to estimate a ratio of 30 males to 9 females (3.3:1 M:F). In stark contrast, only 1 male and 1 female crocodile were captured. A total of 85 C. acutus and 205 C. crocodilus were observed. Regarding the number of caiman sightings in the TNP, a statistically significant difference was found (Χ2=5.62, p≤0.05) for the distribution by sizes between the zones of BACORE and TNP, whereas no such difference was found for C. crocodilus sightings (Z=–1.22, p≥0.222). Some segments had a higher probability of caiman occurrence than did others in the surveys performed during the monitoring period (X2=8.36, p≤0.05), especially the Jalova-Sierpe River, Caño Negro-Tortuguero, and Tortuguero-Samay Lake (Tortuguero subarea) segments. Ninety percent of the sightings occurred in the BACORE zone, and this was significantly different (Χ2=7.34, p≤0.026) from the studied subareas. The number of crocodile sightings in the Colorado River segment was significantly different and higher than the other segments (X2=7.28, p≤0.05). There was a significant statistical difference among the sizes in all areas of study (X2=5.529, p≤0.026). The abundance of C. acutus and C. crocodilus in the north Caribbean part is lower than in the central Caribbean part of Costa Rica, where this species could use the resources available in more urbanized areas.

scholarly journals Population status of the American crocodile, Crocodylus acutus (Reptilia: Crocodilidae) and the caiman, Caiman crocodilus (Reptilia: Alligatoridae), in the Central Caribbean of Costa Rica

2019 ◽  
Vol 67 (6) ◽  
Author(s):  
Juan Rafael Bolaños Montero ◽  
Juan José Sánchez Ramírez ◽  
Luis Sigler ◽  
Brady Barr ◽  
Iván Sandoval Hernández
Keyword(s):  
Costa Rica ◽  
Relative Abundance ◽  
Reproductive Age ◽  
Homogeneous Distribution ◽  
Population Status ◽  
Caiman Crocodilus ◽  
Crocodylus Acutus ◽  
The Pacific ◽  
American Crocodile ◽  
Water Courses

American crocodile (Crocodylus acutus)(Reptilia:Crocodilidae) and caiman (Caiman crocodilus)(Reptilia:Alligatoridae) population status, in the Costarican Central Caribbean. Two species of crocodilians have been described in Costa Rica, american crocodile (Crocodylus acutus: Cuvier 1807), and caiman (Caiman crocodilus: Linnaeus 1758). In Costa Rica, data has been generated on both species, but populations in the Pacific have received more attention from researchers; due to the fact that the Pacific slope has a greater development, which brings greater social pressure on the attention of the incidents generated by the encounter between humans and crocodiles. This study, performed during 2017, was done in an area of approximately 400 km2, characterized by having a wide and dense network of water courses, which includes the Matina, Pacuare, Reventazón and Parismina rivers. In these rivers, an average of 25 kilometers were traveled from the coastline up stream to the interior of the territory, including the Tortuguero canals, and other water bodies that connect these rivers, as well as in the most important lagoons and secondary channels. Three repetitions were made per segment. A population of 1084 caimans and 503 crocodiles is estimated; for a relative abundance of 8.64 and 2.80 ind/Km respectively. Speaking of caimans, up to 12% of individuals of reproductive age were observed, while for crocodiles that number was only 2%. The presence of both species in the different places studied, turned out to be significantly different for crocodiles and for caimans (Kruskal-Wallis, p≤0,000). Likewise, the size distribution is similar for crocodiles reported in all environments (Kruskal-Wallis, p≤0.15), while for caimans it indicates that there is a different distribution for sizes, according to the environment in which they are found (Kruskal -Wallis, p≤0,000), with a bias against of the Pacuare and Matina rivers. It was possible to estimate a sex ratio of 1.25 and 0.83 males to females, in crocodiles and caimans respectively, with 9 and 11 captures in that same order, in individuals of recruits, juvenile and subadult sizes. The Matina River and the Jalova Lagoon are the two main sites for the observation of crocodiles, their abundances are lower than those reported for the Pacific of Costa Rica, in whereas caimans, with a more homogeneous distribution throughout the sampling area, have a relative abundance considerably more than that reported in  Honduras (2.2 ind/km), but lower than the 12.5 reported forLa Rambla de Sarapiquí, in the Northern Zone of Costa Rica.

scholarly journals Factors influencing the occurrence of negative interactions between people and crocodilians in Mexico

Oryx ◽  
2021 ◽  
pp. 1-9
Author(s):  
Giovany Arturo González-Desales ◽  
Luis Sigler ◽  
Jesús García-Grajales ◽  
Pierre Charruau ◽  
Martha Mariela Zarco-González ◽  
...  
Keyword(s):  
Anthropogenic Activities ◽  
Biosphere Reserve ◽  
Rigorous Evaluation ◽  
Caiman Crocodilus ◽  
Crocodylus Acutus ◽  
American Crocodile ◽  
Nesting Sites ◽  
The Relationship ◽  
Nesting Season ◽  
Negative Interactions

Abstract Negative interactions between people and crocodilians have increased worldwide, but in Mexico there have been few systematic reports and no rigorous evaluation of this problem. We compiled information on negative interactions between people and the spectacled caiman Caiman crocodilus and American crocodile Crocodylus acutus from the Worldwide Crocodilian Attack Database for 1993–2018, and we investigated interactions in greater depth, through interviews with people in La Encrucijada Biosphere Reserve. We examined the relationship between the occurrence of negative interactions between people and C. acutus and the species' nesting season and abundance, and presence records. In Mexico, the frequency of negative interactions increases when anthropogenic activities occur close to nesting sites (< 30 km) and during the nesting season (February–September). In La Encrucijada, following negative interactions with crocodiles, the local inhabitants killed 30 crocodiles measuring > 2.5 m long in 2011–2012. The frequency of negative human–crocodilian interactions was not correlated with the abundance of crocodilians but was correlated with the number of presence records of crocodiles. Strategies to minimize these interactions include warnings at nesting sites, increased monitoring of anthropogenic activities during the nesting season, and management of nests to prevent them being destroyed by people.

scholarly journals Characteristics of Xanthomonas cucurbitae Isolates from Pumpkins and Survival of the Bacterium in Pumpkin Seeds

Plant Disease ◽  
2018 ◽  
Vol 102 (9) ◽  
pp. 1779-1784 ◽  
Author(s):  
X. Zhang ◽  
M. Babadoost
Keyword(s):  
The United States ◽  
Culture Collection ◽  
Colony Development ◽  
North Central Region ◽  
North Central ◽  
The North ◽  
Significant Difference ◽  
Optimum Ph ◽  
Pumpkin Seeds ◽  
Maximum Temperatures

This study was conducted to determine characteristics of Xanthomonas cucurbitae, the causal agent of bacterial spot of pumpkin, and survival of the bacterium in pumpkin seeds. Fourteen X. cucurbitae isolates from the north central region of the United States, along with the X. cucurbitae strain 23378 from the American Type Culture Collection, were included in this study. The range of minimum, optimum, and maximum temperatures for colony development of X. cucurbitae were 4 to 6°C, 24 to 30°C, and 34 to 36°C, respectively. Optimum pH for colony development ranged from 6.5 to 8.0. Leaves of 3-week-old pumpkins ‘Howden’ and ‘Dickinson’ were inoculated with X. cucurbitae isolates (108 CFU/ml). There was a significant difference in the postinoculation periods for appearance of bacterial lesions on the leaves among the isolates; however, there was no significant difference in diameters of the lesions on each of the pumpkin cultivar 7 days after inoculation. Four of the isolates caused significantly larger lesions on ‘Dickinson’ leaves than ‘Howden’ leaves. Naturally infected ‘Howden’ pumpkin and inoculated ‘Dickinson’ pumpkin seeds with X. cucurbitae were stored at 4 and 22°C. X. cucurbitae was isolated from both naturally infected and inoculated seeds 24 months after storage at both 4 and 22°C, and the isolated bacteria were pathogenic.

scholarly journals The origin of glacial alpine landscape in Tröllaskagi Peninsula (North Iceland)

2016 ◽  
Vol 42 (2) ◽  
pp. 341 ◽  
Author(s):  
N. Andrés ◽  
L. M. Tanarro ◽  
J. M. Fernández ◽  
D. Palacios
Keyword(s):  
North Atlantic ◽  
Little Ice Age ◽  
Ice Age ◽  
Important Advance ◽  
North Central ◽  
The North ◽  
Significant Difference ◽  
Rock Glaciers ◽  
Basalt Plateau ◽  
Tertiary Basalt

The Tröllaskagi peninsula is located in north central Iceland, between meridians 19º30’W and 18º10’W , limited by Skagafjödur fiord to the west and the Eyjafjödur fiord to the east, jutting out into the North Atlantic to latitude 66º12’N and linked to the central Icelandic highlands to the south. The peninsula is a Tertiary basalt plateau topped by flat summits with altitudes of 1000-1500 m, intensely dissected by the drainage network. The aim of this present study is to synthesize the recent advances in our understanding of the landscape and its dynamics in the Tröllaskagi peninsula and find the origin of its significant difference from the rest of Iceland. Results of the most recent research suggest the situation of Tröllaskagi as ice-free, delimited by the two great glacial outlets flowing down from the Icelandic Ice Sheet through the Skagafjödur and Eyjafjödur fiords, from at least the Oldest Dryas to the end of the Early Preboreal. Inland in Tröllaskagi, the glaciers formed in the north-facing cirques without losing their alpine characteristics during the Late Pleistocene and Holocene. The advances of these glaciers during the Oldest, Older and Youngest Dryas and the Early Preboreal were only a few hundred metres greater than the most important advance in the second half of the Holocene, during the Little Ice Age. Only a few of these glaciers remained debris-free and are sensitive to the minor climate oscillations. The rest, due to the important geomorphological activity on their walls, developed into debris-covered and rock glaciers and lost this significant dynamism.

Population Ecology of American Crocodile (Crocodylus acutus) in Coiba National Park, Panama

2015 ◽  
Vol 49 (3) ◽  
pp. 349-357 ◽  
Author(s):  
Miryam Venegas-Anaya ◽  
Armando H. Escobedo-Galván ◽  
Sergio A. Balaguera-Reina ◽  
Faith Lowrance ◽  
Oris I. Sanjur ◽  
...  
Keyword(s):  
Population Ecology ◽  
National Park ◽  
Crocodylus Acutus ◽  
American Crocodile

scholarly journals Further records of smaller mammals from the Kalahari Gemsbok National Park

Koedoe ◽  
1975 ◽  
Vol 18 (1) ◽  
Author(s):  
I.L. Rautenbach ◽  
J.A.J. Nel
Keyword(s):  
South Africa ◽  
National Park ◽  
Field Work ◽  
Central Portion ◽  
North Central ◽  
The North ◽  
First Time

An earlier paper (Rautenbach 1971) summarized documented distributional data on the smaller mammals in the Kalahari Gemsbok National Park, Republic of South Africa. Since then continued field- work in this Park (e.g. Nel and Rautenbach in press) has yielded more information on the distribution of some previously recorded species,whilst other species have been recorded for the first time. Collecting hasbeen concentrated on two localities in the vicinity of Twee Rivieren, two near Nossob Camp, as well as at Dankbaar in the north-central portion of the Park.

scholarly journals Population status and species diversity of wetland birds in the Rapti and Narayani rivers and associated wetlands of Chitwan National Park, Nepal

2017 ◽  
Vol 9 (6) ◽  
pp. 10297 ◽  
Author(s):  
Bed Bahadur Khadka ◽  
Paras Mani Acharya ◽  
Sunil Lal Rajbhandari
Keyword(s):  
Species Diversity ◽  
National Park ◽  
Aquatic Vegetation ◽  
Population Census ◽  
Population Status ◽  
Wetland Birds ◽  
Migratory Waterfowl ◽  
The North ◽  
Chitwan National Park ◽  
Autumn And Winter

 In autumn and winter, 24 migratory waterfowl species from the north utilise the wetlands of Chitwan National Park, which provide vital staging, roosting, resting, foraging and breeding places. The birds stay for about eight months before returning north in March and April. These birds are indicators of healthy wetlands, and they distribute nutrients through their droppings that increase primary production of aquatic vegetation and fish. A population census of wetland birds was conducted during January 2014 in Chitwan National Park on the Rapti and Narayani rivers and associated wetlands, including Lami Tal, Tamor Tal, Garud Tal, Devi Tal and marshes and lakes around Temple Tiger. The study found that the Ruddy Shelduck Tadorna ferruginea was the migratory waterfowl with the largest population in these rivers.

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