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Published Jan 15, 2025
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We carried out the study in San Pablo Tejalpa, municipality of Zumpahuacán, Central México, in the Totláli Ecological Park (18 ° 51'43.9 "N and 99 ° 35'31.8" W; 1719 masl),
and in the adjacent fragment of tropical deciduous forest situated on a steep slope, both located.
The prevailing climate is temperate semi-warm-subhumid (A) C (W2) W (i) g, with an average annual temperature of 17°C,
a maximum annual temperature of 32ºC and a minimum annual temperature of 2.4°C.
We established nine count points in the park zone composed by a mosaic of different habitats:
remnants of tropical deciduous forest, organic lemon cultivation, and lawn.
In order to maintain approximately constant 100 m distances between points and due to irregular shape of the park’s limits,
some count point lay in corn cultivation adjacent to the park (1T, 2T, 8T).
Also, we placed ten 100m-distanced count points on the top of the cliff corresponding to the edge of the deciduous forest and not inside this forest,
because this forest lay on a very steep slope,
which made difficult the placement of count points and the mist nets inside its vegetation.
During bird trapping, we put mist nets near the centre of each count point.
During the first day, we began the study with the observations in the forest zone, using 10 × 40 or 8 × 40 binoculars (7:00 a.m. to 9:30 a.m. and 4:00 p.m. to 6:30 p.m.).
To avoid a possible effect on birds’ behaviour produced by the arrival of the observer,
we waited a couple of minutes before starting the counting in the next point
and then, during 10 min, we recorded individuals of each bird species, within a 50-meter-radius circle around the counting point.
During the second day, in the park, we sampled birds with mist nets (12 mx 3 m, 36 mm mesh) (7:00 a.m. to 9:30 a.m. and 4:00 p.m. to 6:30 p.m.).
We checked the nets every hour, placed the captured birds in fabric bags and transported them to the ringing area for processing.
To avoid a possible negative effect of netting on the subsequent point count or vice versa, in the next field visit, we changed the order of sampling method (forest – mist nets, park – point count).
We recorded: the code of the sampling point where each bird was observed or trapped, time, sampling day, bird species, and in the case of the counting point monitoring, the number of individuals per species.
T - survey points in the park
C - survey points in the forest
Column A - codes of the birds rings (birds bands)
O - birds captured and ringed for the firest time
R - birds recaptured
P - bird captured and recaptured leter on
To test for the existence of double counting, we associated each trapped and re-trapped bird with the respective mist net.
We estimated the straight-line distances between the survey points (center of the mist nets) using GoogleEarth v. 7.3.6.9796 (Google 2024),
and calculated the probability of a bird to be caught, as the ratio birds recaptured/captured.
We plotted on a map of the study area, connecting with arrows the nets of the first capture of an individual, with the nets of the recapture.
We adjusted the regression lines for the relationship probability of recapture vs. distance of recapture for each of both study areas.
We calculated the probabilities of recapture for the intervals between mist nets distanced by 99 m, for example 100 – 199 m, 200 – 299 m, etc.
