scholarly journals Nesting Ecology of West African Dwarf Crocodiles in a Heavily Disturbed Landscape in Chirehin, Ghana

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Emmanuel Amoah ◽  
Emmanuel Danquah ◽  
James Perran Ross
Keyword(s):  
Ambient Temperature ◽  
Clutch Size ◽  
Incubation Temperature ◽  
West African ◽  
Nesting Success ◽  
Nest Temperature ◽  
Nesting Ecology ◽  
Forest Patches ◽  
West African Dwarf ◽  
Monitor Lizard

West African dwarf crocodiles (Osteolaemus sp. nov. cf. tetraspis) are among the most threatened crocodilians in the world due to unregulated hunting and habitat loss-related population decline. Despite this, many questions about their basic ecology remain unanswered and this inadequate data hampers effective dwarf crocodile management. We describe incubation temperature, nesting success, hatching rate, and clutch size of West African dwarf crocodiles. We monitored 18 nests from the 2017 and 2018 nesting seasons in the Chirehin Community Land—a highly disturbed agricultural matrix in the climatic transition zone of Ghana. We used Hobo tidbit® data loggers to monitor egg chamber temperature and the effect of ambient temperature on nest temperature. The daily mean incubation temperature recorded during the study was 30.7°C (±SD = 0.8°C, n = 240, range = 28–33°C) and it is congruent with the reported value for the species. The findings from this study suggest a weak positive to no correlation between dwarf crocodile incubation temperature and ambient temperature indicating nest temperature is almost independent of ambient temperature. We found a mean clutch size of 8 eggs per nest (SD = ±2; range = 5–13; n = 17) supporting previous reports that this genus has a low clutch size. The mean nesting success and hatching success across the two seasons were 77.8% and 75.3% (SD = ±41.9, n = 18), respectively. Three nests were destroyed by flood and one by an unknown predator suspected to be a West African Nile monitor lizard. Generally, dwarf crocodiles selected forest patches within the highly disturbed landscape for nesting indicating the need to protect the remaining forest patches. Efforts should be made to repeat the study across this species’ range for an improved understanding of its nesting ecology.

scholarly journals A Comparison of the Characteristics and Fate of Barrow's Goldeneye and Bufflehead Nests in Nest Boxes and Natural Cavities

The Condor ◽  
2002 ◽  
Vol 104 (3) ◽  
pp. 610-619 ◽  
Author(s):  
Matthew R. Evans ◽  
David B. Lank ◽  
W. Sean Boyd ◽  
Fred Cooke
Keyword(s):  
Clutch Size ◽  
Canopy Cover ◽  
Forest Edge ◽  
Nesting Success ◽  
The Other ◽  
Nesting Ecology ◽  
Nest Boxes ◽  
Cavity Nesting ◽  
Bucephala Islandica ◽  
Cavity Nests

Abstract Barrow's Goldeneye (Bucephala islandica) and Bufflehead (B. albeola) are cavity-nesting waterfowl that have received considerable attention in studies using nest boxes, but little is known about their nesting ecology in natural cavities. We found larger clutch size, lower nesting success, and different major predators for Barrow's Goldeneyes nesting in boxes versus those nesting in natural cavities, but few differences for Bufflehead. These differences are attributed to the location and physical differences between Barrow's Goldeneye nest boxes and natural cavities that affect their conspicuousness to predators and conspecific nest-parasitizing females. Goldeneye boxes were concentrated in highly visible locations such as trees at water or forest edge. Natural cavity nests, on the other hand, were often abandoned Pileated Woodpecker (Dryocopus pileatus) cavities, which were more dispersed throughout the forest interior and concealed under dense canopy cover. Bufflehead natural cavity nests were typically closer to edges, which may account for their similarity with boxes. We conclude that in some respects, studies of Barrow's Goldeneye that use nest boxes may not be representative of birds nesting in natural cavities, whereas those of Bufflehead are more likely to be so. Comparación de la Ecología de Nidificación de Bucephala islandica y B. albeola en Nidos Artificiales y en Cavidades Naturales Resumen. Los especies de patos Bucephala islandica y B. albeola anidan en cavidades, por lo que con frecuencia han sido estudiadas usando nidos articificales, pero poco se conoce sobre su ecología de nidificación en cavidades naturales. Los individuos de B. islandica que anidan en nidos artificiales presentaron nidadas más grandes, menor éxito reproductivo y distintos depredadores que los individuos que anidan en cavidades naturales, pero detectamos pocas diferencias para B. albeola. Estas diferencias son atribuidas a la ubicación y a las diferencias físicas entre los nidos artificiales y las cavidades naturales de B. islandica que afectan su visibilidad para deprededores y hembras coespecíficas que parasitan los nidos. Los nidos artificiales de B. islandica estuvieron concentrados en lugares muy visibles como árboles al borde del bosque o a la orilla del agua. Por el contrario, las cavidades naturales frecuentemente fueron cavidades abandonadas de Dryocopus pileatus, las cuales se presentaron más dispersas por el interior del bosque y ocultas bajo un dosel denso. Las cavidades naturales de B. albeola se ubicaron típicamente más cerca del borde, lo que tal vez explica la semejanza con los nidos artificiales. Concluimos que en algunos casos, los estudios de B. islandica que utilizan nidos artificiales pueden no ser representativos de individuos que anidan en cavidades naturales, mientras que los estudios de B. albeola probablemente sí sean más representativos.

scholarly journals Changes in serum cortisol concentrations in West African Dwarf (WAD) bucks during electroejaculation

2021 ◽  
Vol 39 (1) ◽  
pp. 31-36
Author(s):  
J. O Daramola ◽  
A. A Adeloye ◽  
I. A Balogun ◽  
M. B Yousuf ◽  
A. O. Olatunde ◽  
...  
Keyword(s):  
Ambient Temperature ◽  
Serum Cortisol ◽  
West African ◽  
Blood Samples ◽  
Late Afternoon ◽  
Treatment Groups ◽  
West African Dwarf ◽  
Group I ◽  
Cortisol Levels ◽  
Group Ii

Changes in the concentration of serum cortisol in blood samples of twenty healthy West African Dwarf (WAD) bucks were determined during electro-ejaculation. The animals were randomly assigned to one of two treatment groups. Group I consisted of bucks that had rectal probe inserted but were not electroejaculated (NEE), and group II consisted of bucks that were electroejaculated (EE) in the morning (0900hr), afternoon (1400hr) and late afternoon (1800hr). The results showed that serum cortisol values found in both groups were similar (P>0.05). Increase in cortisol levels were observed (P<0.05) in the afternoon in both EE and NEE animals in comparison with morning and late afternoon. The findings of this study indicate that the increase observed in cortisol concentrations in the afternoon in both groups reflects stress stimuli due to slight increase in ambient temperature.

Growth performance and blood parameters of West African dwarf rams fed dried Ficus thonningii foliage as supplement to high quality cassava peel

Food Chain ◽  
2019 ◽  
Vol 8 (1-2) ◽  
pp. 58-78
Author(s):  
Bazit Bakare ◽  
Olufemi Onifade ◽  
Victoria Ojo ◽  
Kafayat Adebayo ◽  
Anandan Samireddypalle
Keyword(s):  
Growth Performance ◽  
Blood Parameters ◽  
West African ◽  
High Quality ◽  
West African Dwarf ◽  
Ficus Thonningii ◽  
Cassava Peel

scholarly journals First evidence for a latitudinal body mass effect in extant Crocodylia and the relationships of their reproductive characters

2020 ◽  
Vol 129 (4) ◽  
pp. 875-887
Author(s):  
Rebecca J Lakin ◽  
Paul M Barrett ◽  
Colin Stevenson ◽  
Robert J Thomas ◽  
Matthew A Wills
Keyword(s):  
Clutch Size ◽  
Body Mass ◽  
Linear Models ◽  
Incubation Temperature ◽  
Mass Effect ◽  
Distribution Patterns ◽  
Egg Mass ◽  
Phylogenetically Independent Contrasts ◽  
Extant Species ◽  
Female Body Mass

Abstract Relationships between distribution patterns and body size have been documented in many endothermic taxa. However, the evidence for these trends in ectotherms generally is equivocal, and there have been no studies of effects in crocodylians specifically. Here, we examine the relationship between latitudinal distribution and body mass in 20 extant species of crocodylians, as well as the relationships between seven important reproductive variables. Using phylogenetically independent contrasts to inform generalized linear models, we provide the first evidence of a latitudinal effect on adult female body mass in crocodylians. In addition, we explore the relationships between reproductive variables including egg mass, hatchling mass and clutch size. We report no correlation between egg mass and clutch size, upholding previously reported within-species trends. We also find no evidence of a correlation between measures of latitudinal range and incubation temperature, contrasting with the trends found in turtles.

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