Objective:

The variation of the population structure of M. ornata was evaluated in two fragments (La Montaña and Sarmiento) of Tropical Dry Forest in the Department of Atlántico, Colombia.

Scope:

To determinate the spatial and temporal variations of M. ornata abundance and its relationship with environmental variables, as well as the availability of phytotelmata and the structure of the vegetation.

Methodology:

26 samplings were taken (13 per fragment) every 8 days between 8:00 a.m. and 5:00 p.m. (9 hours/man/fragment). A 600 m long and 30 m large area was established per fragment, where 10 points were marked 50 m apart from each other and in this way, 10 stretches with equal length were obtained. Odonata were captured with entomologic nets using a mark and recapture method. On the other hand, environmental temperature, relative moisture, and light intensity were measured in each stretch, as well as the number of phytotelmata and some of their characteristics (height, density, volume) and the structure of the vegetation (density of trees, vegetal cover, basal area and average height).

Main results:

A total of 90 individuals were captured in La Montaña and released (35 ♂, 55 ♀), 40 of which were recaptured (15 ♂, 25 ♀) once or more times. The highest number of captures (19) ocurred in sampling 2 carried out in March (7 ♂, 12 ♀). In Sarmiento, 31 individuals were captured and released (14 ♂, 17 ♀). In this fragment, the major number of captures was registered in event 1 carried out in March. Taking into account the sex proportions, in La Montaña it was 2:1 (80 ♀, 50 ♂) with significant differences (X2=23.403, p=0.02449), whereas in Sarmiento it was 27 ♀ and 29 ♂ (proportion 1:1) and without differences. With the principal component analysis (PCA), it was determined that the variation in the number of individuals between the places and fragments of sampling, can be explained in 59.76% because of vegetation variables as well as phytotelmata variables.

Conclusions:

it was established that temperature and light intensity are abiotic factors playing an important role in the temporal dynamics of the abundance of this species in the area of study. Additionally, the non random disposition of plant species and vegetation cover, as well as the height of phytotelmata influence the spatial variation of M. ornata in the area.

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