Methods (as taken from the study report): This study was performed at La Estación Biologíca de La Suerte in Pococí, Limón, Costa Rica at 83.77 degrees longitude and 10.43 degrees latitude. The field station at La Suerte is located on the Caribbean side of Costa Rica in the Río Frío district at approximately 50m (150ft) elevation. La Suerte has been both a farm and a plantation in the past but has been managed as a conservation site for over 12 years. The regeneration process has produced two forests. The 'Small Forest' is classified as a primary forest or jungle. The 'Large Forest' is classified as a secondary forest or jungle. The Small Forest is c. 28 hectares in size. The Large Forest is c. 100 hectares in size. The weather conditions in the rainy season, the season during which this study was conducted, are hot, humid and drier than usual. Rainfall usually occurs in the evening and night. La Suerte accumulates approximately 4000 mm of precipitation per year (Clark et al, 1990).
To collect data, the hummingbird first needs to be detected in direct view. The hummingbird then is watched until it started a new behavioral activity while in view. As soon as the hummingbird commences that activity, the stop watch is started. The stop watch used for this study is a Timex: Ironman Triathlon digital wrist watch. Once the hummingbird stops this activity, the stop watch is immediately stopped and the time is recorded. This entire activity can be termed hereafter as an "event". Each event is then described as any of the following: Drinking, Vocalizing, Sitting, Hovering, Flying, Chasing, Being Chased, Playing, Nesting or Fighting. Playing is defined as two or more birds switching off between chasing and being chased within their social interaction event. Fighting is defined as aggressively violent attacks on another hummingbird. Drinking is defined as any time the beak contacted the flower for nectar. Hovering is defined as a maintained stationary aerial position. Nesting is defined as any time a bird entered, left or maintained a nest.
Once the behavior time is recorded, the behavior type is recorded. If the event is "Drinking", then the number of times the individual contacted the flower is recorded. The time of day is observed as a span of time spent observing the individual. This span usually lasts 60 seconds. The type of species is recorded as well as gender if the gender is obvious by coloration. If the species is unknown but the coloration is apparent, then the body description is taken for later classification using A Guide to the Birds of Costa Rica by Stiles and Skutch (1989). If the individual remains unclassified even after consulting the literature, then it is termed as "Unidentified". If the angle of viewing prevents species identification, it also was termed as "Unidentified". It is known that the neck area of males, called gorgets, are dull at certain angle and so their coloration can only be fully realized at angles of direct sunlight (Kricher 1997, page 261). Also events at sunset (around 6pm) can make it too dim for classification.
The plant species is also recorded, if a plant species is involved in the event. If a plant is unknown, then the sample is taken back to the La Suerte library for later identification using textbooks and literature. Photos for later identification were taken if a plant sample could not be attained. The plant height and flower height of that plant are approximated in meters. The forest level is determined as ground level, subcanopy level and canopy level. The Ground Level is defined as less than six meters. The Subcanopy Level is defined as six to 12 meters. The Canopy Level is above 12 meters. The exposure level is also measured by approximating how many angles of direct viewing were possible. The options are "None", "Slight", "Moderate", "Exposed" and "Very Exposed". "None" are defined as being in thick forest so the individual stayed in view with great difficulty. "Slight" is defined as approximately 90 degrees of direct view to the individual. "Moderate" is defined as approximately 180 degrees of direct view. "Exposed" is defined as approximately 270 degrees of direct view. "Very Exposed" is defined as approximately 360 degrees of direct view. Lastly, the trail location is recorded as well as any extra comments on the event.
Observation periods or survey efforts, were not uniform on a daily basis due to weather conditions or class schedule; however, all times of day between 5am and 6:30pm were accounted for more than once to provide enough data to assess if a general hummingbird schedule of activity exists. If a data entry of an event was not clearly or not entirely captured in the observation, the data was not recorded.
It must be realized that not all behaviors were captured. This type of sampling, continuous sampling, means that only one observation can be properly recorded at one time (Martin and Bateson 2005, page 89). This can be an issue if more than one individual is in the area. It affected the study by inhibiting the collection of data regarding the overall amount of activity in the area. If more than one hummingbird was performing the same activity at the same time, then one event was lost so that the other hummingbird could be studied. Also, some actions start out of view or cannot be anticipated, such as vocalization or social interactions that start in direct view but quickly end out of sight. Vocalization was recorded only when the watch started as soon as the chirping began. The social interactions that continue beyond viewing were not included as well.