![ecotone vs continuum ecotone vs continuum](https://1.bp.blogspot.com/-3rrAA2WTcQI/Xsy8e3nRYUI/AAAAAAAAQeA/4TBNNQppUUokBrG34Cjwvyjq0NoywZtHgCLcBGAsYHQ/w1200-h630-p-k-no-nu/PRESENT-SIMPLE-TENSE-VS-PRESENT-CONTINUOUS-TENSE-crop.jpg)
The authors believe that the comings and goings of the female rufous-tailed hummingbird ( Amazilia tzacatl) around its nest may have disturbed the caterpillar, causing it to expose its eyespots, which in turn prompted the hummingbird to defend its nest using what is referred to as ‘mobbing behavior’ by birds - darting flights and pecking at a threat, commonly snakes. The interaction took place on a strip of secondary growth between the Pacific and primary rainforest on the Osa Peninsula, Costa Rica. Observations of how these eyespots affect animal interactions in natural settings are extremely rare. “Mobbing behavior directed against a threat to their nest is much less common but distinct and easy to recognize if you know their other flight behaviors… One can recognize this from a distance and only notice the source of their agitation upon close inspection.”Ĭaterpillars and adults of a variety of butterflies and moths have eye-like spots that deter potential predators. “Hummingbirds have a few stereotypical styles of flying: visiting flowers, preying on swarms of tiny insects, chasing each other, and mating/territorial display flights,” says lead author James H. Marden, professor with the Department of Biology at Pennsylvania State University. The attacking hummingbird’s nest with eggs was about 10cm away from the caterpillar in a small tree. When the researchers went to look for an assumed snake, they instead found the caterpillar feeding on a leaf immediately above the nest. The caterpillar had begun feeding during the night, but the comings and goings of a hummingbird disturbed it, causing it to expand and reveal its “eyes” and rear up into its snake-mimic posture. In particular they resemble a green parrot snake, known to prey on nesting birds. When disturbed, they raise their head up and move from side to side, increasing the snake-like appearance. The caterpillars can inflate the top of their heads to expose a pair of eyespots. These moths - sometimes called the dead-leaf moth or the Costa Rica leaf moth - resemble flat dried leaves as adults. This is exactly what happened in Costa Rica earlier this year, when researchers witnessed a hummingbird defending its nest from what it interpreted to be a snake, but was actually a larva of the moth Oxytenis modestia. The encounter is described in a new paper published in the Ecological Society of America’s journal Ecology. When a caterpillar disguises itself as a snake to ward off potential predators, it should probably expect to be treated like one. Use this information, in addition to the purpose of your analysis to decide what is best for your situation.In a 26-minute standoff, a snake-mimicking caterpillar was unable to feed during attacks from a nest-defending hummingbird. When you treat a predictor as a categorical variable, a distinct response value is fit to each level of the variable without regard to the order of the predictor levels. Treating a predictor as a continuous variable implies that a simple linear or polynomial function can adequately describe the relationship between the response and the predictor.
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If the discrete variable has many levels, then it may be best to treat it as a continuous variable. If you have a discrete variable and you want to include it in a Regression or ANOVA model, you can decide whether to treat it as a continuous predictor (covariate) or categorical predictor (factor). For example, the length of a part or the date and time a payment is received. A continuous variable can be numeric or date/time. Continuous variable Continuous variables are numeric variables that have an infinite number of values between any two values. For example, the number of customer complaints or the number of flaws or defects. Discrete variable Discrete variables are numeric variables that have a countable number of values between any two values. For example, categorical predictors include gender, material type, and payment method. Categorical data might not have a logical order. Categorical variable Categorical variables contain a finite number of categories or distinct groups. Quantitative variables can be classified as discrete or continuous.