Joint effects of inverse density-dependence and extreme environmental variation on the viability of a social bird species

Doxa, Aggeliki; Theodorou, Konstantinos; Hatzilacou, Dionyssia; Crivellì, Alain J.; Robert, Alexandre

doi:10.2980/17-2-3304

Cited by 9 publications

(5 citation statements)

References 68 publications

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“…Earlier studies on Mediterranean Gulls Larus melanocephalus and Dalmatian Pelicans Pelicanus crispus, both colonial breeders as well, also found evidence of inverse density dependence in juvenile annual survival, but not in adult survival (te Marvelde et al 2009, Doxa et al 2010. In colonial breeders, inverse density dependence in juvenile survival might occur during the rearing period when the presence of conspecifics reduces predation risk and thermoregulatory costs (Courchamp et al 1999, Doxa et al 2010. We show, however, that the initial increase in juvenile survival occurs in early winter rather than during the post-fledging period (Fig.…”

Section: Age Effects On Strength and Seasonal Timing Of Density Depenmentioning

confidence: 94%

Seasonal variation in density dependence in age‐specific survival of a long‐distance migrant

Lok

Overdijk²,

Tinbergen

et al. 2013

Ecology

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Density dependence in vital rates is key to population regulation. Rather than being constant, the strength of density dependence may vary throughout the year, but empirical evidence is limited. Based on 22 years of data of color-banded birds from a recovering population of Eurasian Spoonbills Platalea leucorodia leucorodia, we show, for the first time, seasonal variation in density dependence in survival of a long-distance migrating bird. Combining resightings and dead recoveries at breeding, stopover, and nonbreeding areas enabled us to (1) separate true survival from permanent emigration from the breeding area, and (2) estimate survival in three seasons: summer, early winter (including autumn migration), and late winter (including spring migration). Accompanying the rapid population growth, juvenile annual survival initially increased, manifested in early winter, but thereafter, at high population sizes, it strongly decreased through a combination of decreasing survival in all seasons. Annual survival of subadult (second- and third-year) and adult birds decreased more gradually with increasing population size, with density dependence occurring in early winter for subadults and late winter for adults. Thus, the shape and strength of density dependence in survival varied with age and season. Understanding the seasonal timing of density dependence, especially with reference to underlying mechanisms, is important for the design of effective conservation strategies.

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Section: Age Effects On Strength and Seasonal Timing Of Density Depenmentioning

confidence: 94%

Seasonal variation in density dependence in age‐specific survival of a long‐distance migrant

Lok

Overdijk²,

Tinbergen

et al. 2013

Ecology

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show abstract

“…Based on these life history traits, the identification of endangered species that are expected to be impacted by senescence can be straightforward. For such species, even in the absence of specific data on senescence, we advocate that the effect of senescence be routinely considered in species viability assessment by incorporating generic senescence patterns and quantities (Jones et al 2008, Pe´ron et al 2010) to projection models, as is already done for inbreeding depression (Noe¨l et al 2013) and environmental catastrophes (Doxa et al 2010).…”

Section: Discussionmentioning

confidence: 99%

Actuarial senescence can increase the risk of extinction of mammal populations

Robert

Chantepie

Pavard

et al. 2015

Ecological Applications

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Despite recent acknowledgement that senescence can have negative impact on survival and fertility in natural environments across a wide range of animal species, we still do not know if it can reduce the viability of wild endangered populations. Focusing on actuarial senescence (i.e., the decline of survival probabilities at old ages), we use species-specific demographic information to project the extinction risk of wild populations of 58 species of mammals, accounting (or not) for senescence. Our projections reveal potential negative effects of aging on population viability, with an average decrease of 27% of the time to extinction and a potential deterioration of the population-level projected conservation status in 10% of the species. Senescence is associated with particularly strong increases of the extinction risk in species with low mortality rates and long intervals between litters, independently of their place in the phylogeny, indicating that the pace of life history can be used to forecast the detrimental effects of aging on the viability of species. The aim of the various existing systems of classification of threatened species is to set conservation priorities based on assessments of extinction risk. Our results indicate that the quantitative effects of senescence on extinction are highly heterogeneous, which can affect the ranking of species and populations when setting conservation, priorities. In mammals, based on life history traits of a few species, generic patterns of senescence can be incorporated into projection population models to minimize these biases in viability assessments.

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“…Ecological studies of P. crispus have recently demonstrated that the breeding success as well as the mortality of these birds is significantly dependant on atmospheric conditions: in contrast to other pelican species, breeding success is especially high in wet years. Consequently, increased precipitation results in an increase in colony size due to the enhanced survival of juvenile pelicans (Doxa et al , ). Because the current climate changes cause an increasing number of wet and hot summers at breeding places of P. crispus in the eastern Mediterranean, the number of breeding pairs has started significantly to increase and even several new colonies have been established since 2010 (Deinet et al , Crivelli pers.…”

Section: Discussionmentioning

confidence: 99%

First archaeogenetic results verify the mid‐Holocene occurrence of Dalmatian pelican Pelecanus crispus far out of present range

Nikulina

Schmölcke

2015

Journal of Avian Biology

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Th e paper presents an evaluation of subfossil bird bones from archaeological and geological sites in Europe that shows that birds of the genus Pelecanus occurred far out of their present range between 7.4 and 5.0 ka BP in the Danish archipelago. Additionally, from other northwestern European regions mid-Holocene records of pelicans are known. However, due to morphological similarities there are diffi culties in species identifi cation. In this paper ancient DNA barcoding techniques were used to clarify the species assignment of one of these records for the fi rst time. Our results show that the bone derives from Dalmatian pelican Pelecanus crispus , a species that today breeds in 15 colonies in the eastern Mediterranean. Th is species identifi cation is especially remarkable since the Dalmatian pelican is known to be less migratory. We demonstrate that the appearance and disappearance of pelicans in northwestern Europe coincide with climate parameters, since all records fall within warm periods. Th is applies for the larger group of Danish records during the Holocene thermal maximum in northern Europe as well as for two more groups of records from central Europe and Britain dating to 1.9 and 0.8 ka ago. Recent ecological research on the Dalmatian pelican shows that the species seems to profi t from the modern climate changes and is starting to expand its range. Our paper documents that under special circumstances short-distance migrant birds are also able to expand their ranges to areas far outside of the former distribution areas. Finally, the Dalmatian pelican is presented as an indicator species refl ecting special climate conditions. Th e present study demonstrates not only the possibility to recover avian DNA from at least 7 ka old bones, but the relevance of such genetic analysis in combination with archaeological data, particularly if bones could not be assigned to species level by morphological features. In such cases, aDNA is shown as a valuable tool for the reconstruction of the avifauna of the past.

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Joint effects of inverse density-dependence and extreme environmental variation on the viability of a social bird species

Cited by 9 publications

References 68 publications

Seasonal variation in density dependence in age‐specific survival of a long‐distance migrant

Seasonal variation in density dependence in age‐specific survival of a long‐distance migrant

Actuarial senescence can increase the risk of extinction of mammal populations

First archaeogenetic results verify the mid‐Holocene occurrence of Dalmatian pelican Pelecanus crispus far out of present range

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