Matchmaker, Make Me a Match

April 15, 2021

In a room filled with warm light and optimistic keepers, an egg the size of a quarter lies silently in an incubator, a crack forming along its top. After years of planning, 23 days of incubation, and 36 hours of hatching, a tiny, pink bird with darkened eyes emerges from its shell. A Guam kingfisher—a bird that has been extinct in the wild since 1986—has hatched at Lincoln Park Zoo. A miracle, yes, thanks to the dedicated Animal Care staff who got this chick to this moment. But also the result of data collection and genetic and demographic analysis by population biology scientists!

The Association of Zoos and Aquariums (AZA) Population Management Center (PMC) is a scientific team based at Lincoln Park Zoo. These scientists are dedicated to maintaining genetically diverse and demographically stable populations with behaviorally healthy individuals for the long-term future of zoo and aquarium populations. In non-scientific words? PMC scientists are the matchmakers of the animal world. But what does that mean and what does that look like for the 240 AZA-accredited zoos and aquariums?

Data Collection and Studbooks

First things first: In order to sustainably manage a population, all individuals in the population need to be identified and recorded. Enter, studbooks. ‘Studbook’ is a term to describe the record of all the individual animals in a population, including their ancestry, births, and deaths. Some of these detailed records across AZA zoos date back to the 1860s!

Over time, these studbooks have become more advanced and not only share information about an animal’s ancestry and sex, but also their behaviors, breeding, name, transfer locations, and more. They hold essential information that serves as the foundation for the PMC to make informed recommendations.

Lincoln Park Zoo’s Alexander Center for Applied Population Biology created a sophisticated analysis software in 2006, PopLink, to manage these types of data for use by zoo and aquarium populations. While many of these populations have migrated into a newer software platform, Zoological Information Management Systems, for studbooks, PopLink remains a valued tool used for many wild populations to track the same types of information key to populations with long-term monitoring.

The foundation and starting point for healthy management of any zoo or wild population is having high-quality data on the individuals and their history. It becomes much more challenging to help wildlife populations when we don’t have these data,” says Senior Director of Population Ecology and PopLink creator Lisa Faust, Ph.D.

Genetic and Demographic Analyses

With quality studbook data, the PMC can perform genetic analyses to determine the relatedness of individuals and the population’s overall diversity.

Demographic analyses are performed to look at the population size, number of births, and other population events. All of this information is then used as part of the process for forming breeding pairs or groups. Another sophisticated software package, PMx, helps harness the data in studbooks to better understand how many births are needed and which specific animals to recommend for breeding.

“Using genetics and demography to analyze each population allows us to use studbook data to make important decisions about how to scientifically manage each population. Specialized software helps us be efficient in making these important recommendations,” says Kristine Schad Eebes, director of the PMC.

But just because individuals may be great genetic and demographic matches doesn’t mean they are compatible.

Natural History

When planning for a population, it’s important to also understand the species’ natural history. Are they a solitary species? Do they thrive in colonies? Does sex ratio matter within a group? There are many factors that help determine the best outcome for an individual animal, which can support the sustainability of a population.

Chimpanzees, for example, thrive in multi-male, multi-female troops. Chilean flamingos practice safety in numbers, so they reside in large flocks. Grevy’s zebra, polar bear, and eastern black rhinoceros males only interact with females when it’s breeding season—and live as solitary animals for the rest of the year. So, in addition to a good match, a zoo must also have appropriate habitats to accommodate pairs, groups, and individuals. With studbook data as the foundation, genetics, demography, and natural history become a solid structure in this metaphor.

Individual animal mate preferences, health, welfare, and personality play a role in the matchmaking process, as well. As much as the PMC is focused on populations as a whole, the individuals’ needs are not lost in the process.

Breeding and Transfer Plans

After taking genetics, demography, natural history, and individual needs into consideration, PMC scientists create Breeding and Transfer Plans for more than 500 Species Survival Plans® (SSP) to cooperatively manage each population.

Each SSP has a studbook keeper and a coordinator that represent the population as experts in behavior, husbandry, species life history, habitat space needs, and more. Coordinators also survey the AZA institutions involved in the SSP, often using PMCTrack, another software tool created by the Alexander Center, to understand each institution’s plans for the future, as well as their individual animals’ needs. The coordinator and studbook keeper then work with PMC scientists in a collaborative process to create Breeding and Transfer Plans every one to three years, depending on the species.

“Managing SSPs is a team effort including the coordinator, studbook keeper, PMC scientists, and various advisors with species-specific expertise,” says Schad Eebes. “All of this expertise, knowledge, data, and science go into creating Breeding and Transfer Plans to aid in managing these animal populations.” These plans have recommendations for each individual animal in the population—they will receive either a breed or do-not-breed recommendation, as well as a hold or transfer recommendation. Then, a complicated and choreographed dance happens between AZA-accredited institutions to see the recommendations to fruition.

Babies, Companions, and New Arrivals

Once a transfer recommendation is provided, the logistics begin, including intra-institution communications, permit acquisitions, travel plans, weather monitoring, shipping details, and more. After these steps are complete following weeks and months of planning, an animal arrives at a new institution and a mandatory quarantine period begins. Then, individuals are carefully introduced to their new environment and its inhabitants, when applicable, while being carefully monitored by care staff. If introductions are successful, breeding displays may follow, and if science, individual animal preference, and the stars align, a new addition to the population may soon follow.

The young kingfisher wobbles with its pale translucent wings and bulging dark eyes, opening its two-toned beak in search of a meal. The chick is individual 23830, a descendant of a pair of resident birds at Lincoln Park Zoo. As the chick grows, little pin feathers begin to form around its body, filling in over time with its black-, white-, and burnt orange-colored feathers, blissfully unaware that he is one of only 145 remaining birds of his kind. Saving species is not only a science, but also an art.

Test Your Matchmaking Skills

Chimpanzees are a very charismatic and intelligent species with many individual preferences. In the hypothetical scenario below, try to determine an appropriate Breeding and Transfer Plan to best accommodate this population.

Goal: Provide each individual animal with one of the following recommendations: Hold/Do Not Breed, Hold/Breed, Transfer/Do Not Breed, or Transfer/Breed.


  • Chimpanzees must live in multi-male, multi-female troops (two or more of each sex). • Assume there is only one habitat available at each institution.
  • There can only be one transfer and four individual breeding recommendations (two male-female pairs) across all institutions to sustain the population until the next Breeding and Transfer Plan in two years.
  • Consider age, sex, health, history of breeding success, and the number of existing relatives in your recommendations.



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