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Excavation revealed that from the entrance, the burrow sloped downwards and turned 180° before coming to the nest chamber.
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The Crab Plover Dromas ardeola is endemic to the Indian Ocean basin and breeds on islands around the Arabian Peninsula. Unique among shorebirds, it nests in an underground burrow where it lays a single white egg and feeds one chick. We investigated sex-related differences in body size and parental care of this species in Saudi Arabia. Molecular sex...
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In species where both parents cooperate to care for their joint offspring, one sex often provides more care than the other. The magnitude of such sex differences often varies both between and within species and may depend on environmental conditions, such as access to resources, predation risk and interspecific competition. Here we investigated the...
Citations
... Nest, lek and burrow cameras also have been used to identify, or 'resight', uniquely marked individuals (e.g. Johnston et al. 2003, Almalki et al. 2014, Clauser & McRae 2017, Toy et al. 2017, Weston et al. 2017. For some species, camera data have been used to describe space-use and augment traditional resighting data in estimation of parameters such as fidelity, survival and movement. ...
The estimation of abundance is fundamental to ecology and conservation, but often is difficult or impossible to accomplish reliably. Recent improvements in wildlife cameras and ecological modeling have allowed for improved accuracy in estimates of abundance. In this study, we paired nest captures and high‐definition nest video camera monitoring with modeling for a novel approach to estimate survival and abundance of threatened Piping Plovers Charadrius melodus breeding on Missouri River sandbars. From 2005–2014, we captured individuals on nests and uniquely marked them and recaptured previously marked individuals. In 2015–2017, we resighted marked individuals using small, high‐definition video cameras deployed at nests, and counted the number of marked and unmarked breeding individuals associated with nests. We estimated apparent survival and derived estimates of the abundance of breeding individuals and population growth each year using a state‐space Jolly‐Seber superpopulation model with the addition of a binomial band ratio model for data collected using nest video cameras. Apparent survival averaged 0.73 ± 0.03 (mean ± SD) throughout the study. The number of breeding individuals varied, with the population increasing from 2012–2017, following a major habitat creation event. This study provides one of the few examples of camera data being used to produce demographic parameter and abundance estimates for an avian species. The camera and modeling methods described in this study may be applicable to other avian species where some portion of the breeding population is uniquely marked.
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... Crab Plovers are unusual among shorebirds as their modal clutch size is one or, rarely, two eggs (Tayefeh et al. 2013). Crab Plovers exhibit extended parental care, which is biparental at the breeding areas (Almalki et al. 2015) and probably uniparental at the wintering areas (De Sanctis et al. 2005). Parental care extends up to 8 months, which is longer than any other shorebird (De Sanctis et al. 2005). ...
The monotypic Crab Plover Dromas ardeola winters around the shores of the Indian Ocean and breeds in colonies on islands around the Arabian Peninsula. The IUCN lists the world population of Crab Plovers as stable, but long-term survey data or demographic estimates regarding the species status are lacking. Here, we use survey and demographic data collected from 2011 to 2015 to study the status of the population of Crab Plover at their most important wintering area: the Barr Al Hikman Peninsula in the Sultanate of Oman. Our survey data showed that the population of Crab Plovers initially increased and then stabilized. The overall observed finite rate of population change (\(\bar{\lambda }_{\text{obs}}\)) was estimated at 1.004 (0.995–1.013 95% Bayesian credible interval [BCI]), indicating a stable population (7000–9000 birds), that is possibly at carrying capacity. Based on mark-recapture data, the mean annual apparent survival probability of Crab Plovers was estimated to be 0.90 (0.85–0.94 95% BCI). We used counts of adults and yearlings to estimate the mean annual fecundity rate at 0.06 young per pair. Using these demographic values, the overall mean expected finite rate of population change (\(\bar{\lambda }_{ \exp }\)) was estimated to be 0.949 (0.899–0.996 95% BCI), so there is a low chance that \(\bar{\lambda }_{\text{obs}}\) and \(\bar{\lambda }_{ \exp }\) overlap. \(\bar{\lambda }_{\text{obs}}\) and \(\bar{\lambda }_{ \exp }\) would completely match if about 450 Crab Plovers immigrate to Barr Al Hikman each year. Regional surveys show that yearling densities are higher closer to the breeding areas, so immigrants could be birds that during their first winter stayed close to their natal area. Our study support the IUCN listing of Crab Plover as stable, but further population-wide monitoring is required. From a conservation point of view it is important to continue monitoring because Crab Plovers breed and winter in a region that is rapidly developing.
... Crab Plovers normally lay a single large, white egg that is only partly incubated by the parents, since temperatures inside burrows are thought to be near-optimal for incubation , 2015a. After nests hatch, both parents provide their offspring with food (Almalki et al. 2015). Provisioning continues after the post-breeding migration (De Sanctis et al. 2005). ...
... Several studies report that crabs are a major food source for Crab Plovers, during both the breeding season (Almalki et al. 2015, De Marchi et al. 2015b) and winter (Swennen et al. 1987, Soni 2007. Occasionally fishes, prawns, worms, mollusks (Soni 2007, Almalki et al. 2015 and mudskippers (Cramp et al. 2004, Behrouzi-Rad & Behrouzi-Rad 2010 have been observed in the diet of Crab Plovers. ...
... Several studies report that crabs are a major food source for Crab Plovers, during both the breeding season (Almalki et al. 2015, De Marchi et al. 2015b) and winter (Swennen et al. 1987, Soni 2007. Occasionally fishes, prawns, worms, mollusks (Soni 2007, Almalki et al. 2015 and mudskippers (Cramp et al. 2004, Behrouzi-Rad & Behrouzi-Rad 2010 have been observed in the diet of Crab Plovers. In our study area, mudskippers made up as much as 25% of the chick diet. ...
The Crab Plover Dromas ardeola is an uncommonly studied wader, renowned for breeding in colonies inside self-excavated burrows on islands around the Arabian Peninsula. This study presents counts and observations on the breeding biology in several colonies on the Bubiyan Islands in Kuwait during 2012–2014. Up to 1,750 burrows of Crab Plovers were found in a single year. We estimate that at least 3–5% of the world population uses the Bubiyan Islands for reproduction, making it a very important area for this species. Burrow densities were much higher than those reported in Iran, United Arab Emirates and Eritrea, but nesting habitat availability did not seem to limit the number of nests because colonies never extended over entire islands. The breeding season extended from April to July, and this timing was similar to nearby areas in Iran. The food that the Bubiyan Crab Plovers brought to the colonies for their young consisted of crabs (75% of all observed prey items) and mudskippers (25%). A review of the currently known breeding areas shows that the breeding areas of Crab Plovers are confined to at least 56 colonies at 19 sites. All colonies except two can be found in the Arabian Gulf and Red Sea, with the Arabian Gulf hosting about two thirds of all breeding Crab Plovers. The colonies on the Bubiyan Islands are among the five largest known colonies of Crab Plovers around the world.
Intermittent incubation in birds is currently interpreted as the result of trade-offs between the needs of the embryo and those of the parents. However, the low nest attendance in some species is still puzzling. We studied the Crab Plover (Dromas ardeola), a tropical burrow nesting shorebird with very low incubation constancy (less than 55%) due to frequent recesses from incubation (on average 5 recesses/h), mostly spent in the colony area without any apparent function. We aimed to test whether such unusual incubation rhythm can be partly explained by the need to scan for approaching predators. Data collected at Dahret Island (Eritrea) between 2006 and 2014 support the antipredatory function of the incubation rhythm: (1) many recesses on the colony surface were so short (50% less than 37 s in the hotter periods) that a thermoregulatory function can be dismissed; (2) adults on the colony surface responded to approaching predators with alarm calls that drove most incubating Crab Plovers to run out of the burrows and to escape in flocks; (3) sound intensity sharply decreased inside burrows, which explains the delayed escape observed for 9% of the incubating birds; (4) the delayed exit when predators were still in the colony area rules out their permanence inside burrows as an alternative antipredatory strategy; (5) after the visit of a predator, adults restarted incubation with very short in-bouts (2 min on average) apparently in order to scan frequently for approaching predators. We discuss how burrow nesting, alarm calls, and the antipredatory reactions of adults (escape into or out of the burrows, flock flight, mobbing) and chicks (escape into burrows) might have favoured colonial breeding in Crab Plovers.
