Les hommes ont oublié cette vérité. Mais tu ne dois pas l'oublier, dit le renard. Tu deviens responsable pour toujours de ce que tu as apprivoisé.
Le Petit Prince, chap. 21
Showing posts with label turtles. Show all posts
Showing posts with label turtles. Show all posts

Tuesday, 15 July 2014

Dog scavenging sea-turtle nests

Ruiz‐Izaguirre, E., Woersem, A., Eilers, K., Wieren, S. E., Bosch, G., Zijpp, A. J., & Boer, I. J. M. (2014). Roaming characteristics and feeding practices of village dogs scavenging sea‐turtle nests. Animal Conservation.

Village dogs are reported to prey on sea-turtle nests at various beaches worldwide. Sea-turtle species present in Mexico include six species, which are listed under the International Union for Conservation of Nature Red List. It is however not clear why dogs scavenge and how they enter nesting areas; this hinders effective management of dogs at sea-turtle nesting beaches. Hunger, for example, could be a driving factor for village dogs to scavenge sea-turtle nests. The aim of this study was to gain insight into roaming characteristics and feeding practices of dogs scavenging sea-turtle nests. Movements of 19 village dogs (9 nest scavengers and 10 non-nest scavengers) at Colola village and beach (an important nesting ground for the eastern Pacific green turtle: Chelonia mydas) were monitored through radio-tracking and direct observations. A prerequisite for nest scavenging is traveling to the beach. We computed ‘distance from home to beach’ and ‘the activity range’ of nest scavengers and non-nest scavengers. Furthermore, the dogs' owners were interviewed regarding feeding practices. Nest scavengers had a lower metabolic energy intake of their daily food corn tortillas (296 kJ kg−1 BW0.75) than non-nest scavengers (464 kJ kg−1 BW0.75) (two-sample t-test=2.67, P=0.017). Moreover, 39% of owners reported that they provided turtle eggs or egg shells to their dogs at least once. The activity range of nest scavengers was significantly larger than that of non-nest scavengers (F=11.64, P=0.007). Dogs were generally found at the beach at night (42%) and dawn (34%). Our findings have implications for the management of dogs at sea-turtle nesting beaches. We recommend that dogs' movements should be restricted between night (09:00 pm) and dawn (06:00 am) and that sufficient and adequate feeding of dogs should be promoted among dog owners.

Thursday, 27 February 2014

Behaviour of village dogs in coastal Mexico


Ruiz-Izaguirre, E., Eilers, K., Bokkers, E. A., Ortolani, A., Ortega-Pacheco, A., & de Boer, I. J. (2014). Human–dog interactions and behavioural responses of village dogs in coastal villages in Michoacán, Mexico. Applied Animal Behaviour Science.


In Mexican villages, most households keep dogs that roam freely. Therefore, socialisation of village dogs occurs in a different context than that of companion dogs in developed countries. The objectives of this study x: (1) to assess village dogs’ behavioural responses towards familiar and unfamiliar humans, (2) to compare body condition of dogs living in a village with a seasonal trade in international tourism (IT-village) with dogs living in a village located in the vicinity of a sea-turtle nesting site (STN-village), and (3) to identify whether dog characteristics influence dog behaviour and body condition.

Two coastal villages in Michoacán, Mexico, were selected as case study sites. Fifty-nine dogs were initially visited, 35 of which were repeatedly visited during the high and low seasons for international tourism and sea-turtle nesting. Caregivers were interviewed regarding human–dog interactions, and dogs were behaviourally tested and rated for body condition. Behavioural indicators were: 1) the dog's qualitative response to a caregiver's call and 2) the dog's willingness to approach an unfamiliar human. Additionally, a dog census per village was conducted to ascertain the dog population structure. Dogs were kept by over 60% of households in both villages. Body condition was optimal for 68% of the dogs. In the low season, dogs in the STN-village had better body condition than dogs in IT-village (P = 0.007). Dog characteristics that influenced behavioural responses were: sex, age, and whether the dog played with humans. The most common response to the caregiver's call was tail wagging, shown by 83% of male dogs and 50% of female dogs (P=0.021). About 70% of the pups approached the unfamiliar human completely, whereas only 24% of the juveniles (P =0.040) and 26% of the adults did so (P =0.026). Human–dog play was reported to occur mainly with children (77%). The percentage of dogs that played with humans was higher in dogs responding with tail wagging (82%) than in dogs showing the rest of the response categories (withdrawal, baring teeth, and other) (50%) (P =0.012). Human—dog play was reported for 85% of the male dogs compared to 55% of the female dogs (P=0.036). This study showed that village dogs were socialised to familiar humans but were not attracted to unfamiliar humans. Village dogs maintained their body condition in the low season. Child–dog play may have a role in shaping village dog social behaviour towards humans.



Monday, 18 November 2013

Dogs predating on green turtle nests

Fowler, L. E. (1979). Hatching success and nest predation in the green sea turtle, Chelonia mydas, at Tortuguero, Costa Rica. Ecology, 60 (5) 946-955.

Green turtle hatching success and nest predation were investigated at Tortuguero, Costa Rica, during July-November 1977. Forty-two percent of 350 study area nests and 57% of 237 beach survey nests produced emerging young; 38% and 24%, respectively, were destroyed by dogs, coatis, and vultures. The mean emergence percentage for the successful study area nests was 83%. About 13% of all eggs deposited did not hatch. A mean incubation period of 62 d and a mean clutch size of 104 eggs were recorded. Emergence success was not influenced by other recorded parameters (nest position on beach, rainfall, turtle's tag year, time of season, incubation period, and clutch size). Incubation period was related to nest position and clutch size. Dogs, coatis, and black and turkey vultures were the chief predators at Tortuguero; dogs did the most damage. Dogs and coatis found nests at all stages of development, but destroyed more nests containing hatchlings than nests containing unhatched eggs. Predation was related to nest position, but not to nest density. Nests were destroyed in equal proportion on the entire 35.4 km of beach. Predator activity was not consistent throughout the season; proportionally more nests were destroyed near the end of the nesting season than during the beginning.

Friday, 8 November 2013

Community turtle conservation in Costa Rica

Govan, H. (1998). Community turtle conservation at Rio Oro on the Pacific coast of Costa Rica. Marine Turtle Newsletter, 80, 10-11.

In June 1996, ADECORO started community-based management of the beach which involved both the participation of community members in controlling movements of their animals, and the removal of feral dogs which was carried out in conjunction with local authorities.


Total Predated
% Predated
1994
417
15%
1996
292
9%
A marked reduction can be seen in predation levels subsequent to the commencement of this initiative. It is almost certain that the reduction of dog predation is the result of a combination of the activities of the beach patrols and general increasing awareness in the community. Increased public awareness is likely to have contributed to the decrease in the activities of human egg collectors. The number of nests collected by humans fell from 344(12%) in 1994, to 122 (4%) in 1996

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Saturday, 13 April 2013

Cat predation on turtle hatchlings

Seabrook, W. 1989. Feral cats (Felis catus) as predators of hatchling green turtles (Chelonia mydas). J. Zool., Lond., 219: 83-88

In many parts of the world feral animals have been reported to have severe effects on marine turtle hatchling production. In this study, green turtle (Chelonia mydas) hatchlings were shown to be an important component of the diet of the feral cat (Felis catus) on Aldabra Atoll, Seychelles, and feral cat activity in the coastal areas was found to be concentrated on the beaches used most intensively by turtles for nesting. The impact of the feral cat's predation on green turtle recruitment could not be determined. However, despite cat predation, the size of the Aldabran green turtle nesting population has increased considerably since human exploitation ceased.

Monday, 18 March 2013

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