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...
Underlying medical conditions may be the cause of heart palpitations. These include: overactive thyroid; anemia; low blood sugar; low potassium; dehydration; high temperature and fever; loss of blood; shock; low oxygen or carbon dioxide levels in the blood; Hormone changes. Hormonal changes are another possible cause of heart palpitations. Changes in hormone levels may result from: menstrual periods; pregnancy; menopause; Heart conditions. Palpitations can also be caused by heart conditions, including: arrhythmias (abnormal heart rhythms) coronary artery disease or a heart attack; heart valve problems; heart failure