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...
Often the cause of your heart palpitations can't be found. Occasionally heart palpitations can be a sign of a serious problem, such as an overactive thyroid gland (hyperthyroidism) or an abnormal heart rhythm (arrhythmia). Arrhythmias may include very fast heart rates (tachycardia), unusually slow heart rates (bradycardia) or an irregular heart rhythm. 1  Symptoms.  Risk factors.