Coenagrion mercuriale (Charpentier, 1840) is a damselfly classified as ‘Near Threatened’ by the Global IUCN Red List and as ‘Endangered’ in some parts of its range. The species is characterized by fragmented and declining populations with their core in the western Mediterranean and parts of western Europe. This study reported the first estimates of survival rate and population size for a southern European population of Coenagrion mercuriale living in central Italy. Surveys were carried out in 2017 in the peak of the flight period applying capture–recapture models. More than 1200 specimens were captured on 11 occasions and the sex ratio observed was male-biased (2.8:1). Daily survival probabilities ranged from 0.662 ± 0.059 to 0.868 ± 0.045. Maximum longevity was 14 days for males. The maximum number of estimated individuals on any day was 507.2 ± 49.6 for males, and 219.8 ± 27.7 for females in mid-June. The estimate of the cumulative population size was about 4000 specimens, with a mean density of 1.2 individuals/m2 at the breeding site. Our results pointed out that population ecology of the Southern Damselfly in central Italy is similar to that of the populations living in the northern limit of its range. The present study also indicated that monitoring plans, with seven marking occasions at least, can provide consistent estimations of population size, useful for evaluating the viability of populations and for assessing the species conservation status.
Investigation on the declining Southern Damselfly (Coenagrion mercuriale, Odonata) in a Mediterranean population: survival rate and population size
La Porta G.
;Goretti E.
2019
Abstract
Coenagrion mercuriale (Charpentier, 1840) is a damselfly classified as ‘Near Threatened’ by the Global IUCN Red List and as ‘Endangered’ in some parts of its range. The species is characterized by fragmented and declining populations with their core in the western Mediterranean and parts of western Europe. This study reported the first estimates of survival rate and population size for a southern European population of Coenagrion mercuriale living in central Italy. Surveys were carried out in 2017 in the peak of the flight period applying capture–recapture models. More than 1200 specimens were captured on 11 occasions and the sex ratio observed was male-biased (2.8:1). Daily survival probabilities ranged from 0.662 ± 0.059 to 0.868 ± 0.045. Maximum longevity was 14 days for males. The maximum number of estimated individuals on any day was 507.2 ± 49.6 for males, and 219.8 ± 27.7 for females in mid-June. The estimate of the cumulative population size was about 4000 specimens, with a mean density of 1.2 individuals/m2 at the breeding site. Our results pointed out that population ecology of the Southern Damselfly in central Italy is similar to that of the populations living in the northern limit of its range. The present study also indicated that monitoring plans, with seven marking occasions at least, can provide consistent estimations of population size, useful for evaluating the viability of populations and for assessing the species conservation status.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
