NOTES ON HOLE SIZE: 1  per Bergmann's rule, some species of birds may be larger in colder climates-e.g., a Canadian starling may be bigger than a Florida starling, thus the Canadian bird might not be able to fit in a certain hole size that its southern version could squeeze into.
A heart palpitation is the sensation that your heart has skipped a beat or added an extra beat. It may feel like your heart is racing, pounding, or fluttering. You may become overly aware of your heartbeat. This sensation can also be felt in the...
Causes of Heart Palpitations. Many things can cause heart palpitations. In the vast majority of cases, the cause is either related to your heart or is unknown. Non-heart-related causes of palpitations include: 1  Strong emotions such as anxiety, fear, or stress; palpitations often occur during panic attacks.2  Vigorous physical activity.. Heart palpitations are a feeling that your heart is beating too hard or too fast, skipping a beat, or fluttering. You may notice heart palpitations in your chest, throat, or neck. Heart palpitations can be bothersome or frightening.