Learning from lovebirds

Lovebirds know what they’re doing. It only takes zebra finches days to choose a partner, and yet their relationships last a lifetime.

MalikaThat’s what Malika Ihle, behavioral ecologist at the Max Planck Institute for Ornithology, found in her recent study on the birds’ courtship behavior. We speak with her about the secret to finches’ love, and what we can learn from them.  

ResearchGate: Are human and bird love alike in any way?

Malika Ihle: What could be similar to human love is that birds have individual rather than shared preferences, and it’s hard to explain on what criteria these preferences are based. This is sometimes how we define love in humans, so in that sense it could be comparable.

RG: How do finches flirt?

Ihle: In our study it was similar to a speed dating event. We worked with youngbirds who hadn’t come across a mate from the opposite sex yet. We put these single birds into one aviary which gave them plenty of choices. The men got a little bit crazy and they courted intensively. At some point they narrowed down their courtships to one or two females. Then one of those females answered the male call.

At that point we separated some couples again and paired them with another partner they hadn’t chosen. They called for their original partner trying to find them again and looked a little lost. But I put their partners in a room with another assigned partner so they couldn’t hear back from them. After a few days they stopped calling and started looking at their assigned partner. Maybe they considered that this may be their only chance to reproduce so they might as well give in and start reproducing. They do stick to these partners then, and they likely will for their entire life. In captivity that can be up to ten years. We don’t have much data how old these birds get in the wild.

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RG: You found that the pairs who found each other had a 37 percent higher reproductive success. How did the finches know that when they chose a partner?

Ihle: We don’t know that, but it seems that in the course of a couple of days the females learn how to judge how well it will work out with these partners. Just like when you find somebody attractive because they stimulate your senses in a very particular way, the birds may be more drawn to a specific voice or a movement. This might also be what keeps them motivated in their relationship.

We found that the pairs that had chosen each other had a higher fitness – more healthy offspring – than the assigned pairs. This was the result of behavioral and not genetic compatibility. We know this because we know from previous studies that genetic compatibility is related to embryo mortality in zebra finches. Chick mortality reflects behavioral incompatibility. In this experiment the chick mortality was much higher in the assigned pairs. A chick that hatched in the nest of an assigned pair only had a 50 percent chance of surviving.

RG: What’s the secret to their successful relationships?

Ihle: We had the hypothesis that maybe it was a matter of personalities matching, but we didn’t see any evidence for that. What we could see was that the assigned pairs were less committed to each other. Females were less willing to copulate with their assigned partner. Males were eying other females more often and were also a bit less caring of their offspring. Overall they seemed to be less committed to investing in reproduction. What matters – at least in this species – is how well you’re motivated or encouraged by your partner in what it takes to raise your family.

RG: What else can we learn from the finches?

Ihle: The take-home message here might be that it’s not important what the group thinks is good for you, but that it depends on your personal preferences. You need to be yourself and you need to be convinced that who you’re choosing this is good for you.

Pictures courtesy of Wolfgang Forstmeier