Answer: Yes and... No
A discussion of whether birds mate for life has to begin by having an understanding of what we mean by the term "mating for life".
For some, having a mate for life means, marriage for 50 - 60 years, partner passes, and surviving mate lives with fond memories until death. Never to partner with another.
If mating for life means one partner in a lifetime to you, then there are few birds that fit into this category.
Those birds that do fit this category are the ones that die in their first pair bond, as the surviving bird will nearly always attempt to find a new mate. Some will find new mates in the same nesting season.
Others will forage for food through the breeding season, joining flocks in the fall. Still, others will help feed and raise the young of other pairs, but all will attempt to find a new mate at some time.
Most of our North American birds do not mate for life. Rather, most pair bonds are formed for a single season. Those birds that pair for a season are referred to as monogamous pairs.
Monogamy is one male bird with one female bird through a single nesting cycle.
The pair may stay together raising a single brood and then change partners for a second brood in the same season. Still they are considered monogamous.
Other pair bonds may be formed and last over several seasons. Doves, Robins, and others are on this list. Oftentimes, these birds are considered as meeting the definition of "birds mate for life".
Even though their average lifespans may range from a year and a half to several years. Despite whether they mate again after one dies.
When we speak of birds and monogamy, we are not referring to faithfulness. First year mortality rates are very high with regards to our small songbirds and reproduction is a primary goal.
The truth is, DNA evidence points to a high percentage of promiscuity. Many females lay clutches that are determined to be from different males.
This in turn suggest males may breed with more than one female even though a pair bond may have been formed with another female.
Several large birds are considered as mating for life. Among them are: swans, geese, eagles, and some owls.
Why birds mate for life is not as romantic as one may think.
When you factor in the time needed to migrate, establish territories, incubation and raising young, you'll realize that the time and energy needed for attracting a mate would minimize reproductive time.
The Bald Eagle for example, spends just over a month incubating the eggs and 2 1/2 to 3 months raising their young in the nest.
Establishing lifelong pair bonds works to their advantage.
I suppose the question of whether a bird mates for life comes from wondering what will happen should one bird die.
Many believe that birds mourn the loss of their mate, never to mate again.
I can't say whether birds experience loss at some level or whether what we sometimes interpet as mourning, is just confusion. I do know our wild birds will always attempt to find new mates.
Whether a bird mates for a single brood or 40 years, our job is to provide the best environment for them to be successful at what they're attempting to do - raising more birds that we get to enjoy.
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