Birds do cry and shed tears similar to humans but not exactly the same as humans.
Signs that a bird is sad and crying include.
Loss of appetite.
Change in droppings.
Change in vocalizations.
Constant head bobbing.
Birds do get sad and also mourn the loss of other birds when they die.
Birds do understand death and have the ability and capacity to mourn the death of other birds.
Birds do know when another bird dies and birds also grieve the loss of other birds and companions just like humans do.
The birds that are monogamous include swans, geese, ducks, cranes, storks.
For birds specifically, the World Wildlife Foundation found that around 90% of species choose monogamy as their reproductive strategy.
This is a huge number compared to mammals at just 5%.
The thinking behind why birds are generally monogamous is that the parental time investment needed to raise chicks is so large.
Birds do sometimes cheat on each other and in fact some birds can have multiple fathers.
Cheating, or “extra-pair copulation” also occurs, but rarely, among birds of sexually monogamous, mated-for-life species, “but is not yet known how many species engage in extra-pair copulations, since many species remain to be studied.
Birds choose their mates through vocal calls and feathers and fights.
Some male birds gather in leks, not unlike nightclubs, to dance in a group and invite curiosity from nearby females.
Others perform feats of strength and endurance to prove their value.
And in some species, males and females dance together to form a pair bond while putting on a show.
Research has focused on male competition for access to females or territory and on females choosing males based on their feathers and fights.
Although recent investigations suggest that females not only compete with each other, but also rely on such traits in deciding whether to engage or defer.
Birds can sometimes have multiple fathers and in fact some birds can have 3 or even 4 different fathers.
Birds know who to mate with from their voice calls and vocalization.
Birds mate with what is known as a cloacal kiss.
The male bird mounts the female bird from behind, balancing on her back.
She then arches her back and moves her tail to one side.
He then hunches over, and their cloacas touch for just a second.
Most birds of prey do mate for life.
Certain species of birds mate for life, including geese, swans, cranes, and eagles.
It's a true statement, for the most part, but it's only part of the story.
Lots of monogamous bird species cheat, and some “divorce” but at rates much lower than humans.
Most diurnal birds of prey are monogamous.
Some birds keep the same mate for several years, such as ospreys, while others have different mates each year, such as snail kites.
In some groups of Harris' hawks, monogamous breeding pairs are assisted by a number of non breeding helpers, mostly previous offspring.
The bird that stays with it's mate forever is the mute swan.
The mute swan is a species of swan and a member of the waterfowl family Anatidae.
It is native to much of Eurosiberia, and the far north of Africa
The name 'mute' derives from it being less vocal than other swan species.
Measuring 125 to 170 cm (49 to 67 in) in length, this large swan is wholly white in plumage with an orange beak bordered with black.
It is recognizable by its pronounced knob atop the beak, which is larger in males.
Mute Swan pairs reportedly stay together for life.
However, divorce does occur in less than 3 percent of mates that breed successfully and 9 percent that don't.
They re-mate when a partner dies; how quickly this happens depends on the survivor's gender.
Most birds are far from monogamous.
Most birds do not mate for life, and most of those that do aren't quite as faithful as we'd like to think.
Over 92 percent of all bird species form a pair bond and stay together for at least part of the nesting cycle.
Monogamy isn't limited to creatures on land.
According to the U.S. Fish & Wildlife Service, the seahorse is just one of many sea creatures that mate for life.
And fun fact: In these monogamous couples, it's the male that gives birth to the offspring.
About 90 percent of bird species are monogamous, which means a male and a female form a pair bond.
But monogamy isn't the same as mating for life.
A pair bond may last for just one nesting, such as with house wrens; one breeding season, common with most songbird species; several seasons, or life.