A pest around the world

How did house sparrows become a pest? With the spread of agriculture and urbanization sparrows have become one of the abundant groups of birds in the world. Most sparrow species are closely linked with humans and spread with people as humans moved out of Africa and throughout the world. Perhaps the most successful sparrow, and the one we all know about, is the house sparrow, who can be found on every continent in the world save frigid Antarctica. Throughout time, as their abundance has fluctuated so has public opinion about these resilient little birds. Today we will look at the story of sparrows around the world, and how public perceptions and management has changed over time.


As humans moved out of Africa and into Europe, so did our sparrow friends. Being mostly seed eaters, sparrow ancestors were migratory. But the development of agriculture gave sparrows a consistent source of food year round. Like us, they settled, nesting in the buildings we built and eating the crops we produced. During the 1700’s there was an explosion in the European sparrow population as human settlements spread further and agriculture continued to focus on cereal grains such as wheat and oats, an ideal food source for sparrows.

By the mid 1700’s there was a superabundance of sparrows throughout Central Europe, with some written accounts describing flocks of sparrows so large that they blocked out the sun. These enormous flocks of sparrows could decimate important crop yields at a time when cereal grains made up a substantial portion of crops grown in Europe, making the sparrow a worthy foe. To combat this problem, many local governments established a bounty in which sparrow heads could be turned in to the government for tax credits. By the end of World War II, the first observable declines in the European sparrow population were seen. This change is likely due to a decrease in horse manure, more efficient grain harvesting technology, and poultry no longer being fed in the open. It is difficult to know whether the management strategies implemented by governments have led to a continued decline in house sparrow numbers or whether changes agricultural practices have played a bigger role. Ironically, in many European countries today house sparrows are now a protected species as their numbers have declined so much. There are now campaigns in the United Kingdom to save the house sparrow!

A house sparrow eating grain from a bird feeder. Photograph by Tammy McLean


One of the most interesting stories of sparrow control comes from China, during the reign of Mao Zedong and “The Great Leap Forward”. Mao considered the Eurasian tree sparrow (a close relative of the house sparrow) one of the “four great pests” to the nation because of their abundance and negative impact on grain crop yields. In March of 1958 Mao declared war on tree sparrows, and people all over the country went outside banging pots and pans together, waving flags, destroying nests, and killing nestlings with guns and slingshots.

At first, the effort appeared to be a remarkable success as crop yields initially improved. But before long, locust and grasshopper populations, freed from sparrow predation, exploded and decimated the grain crops. The crop damage from the insects lead to a famine in which more than 35 million Chinese people died. In a desperate attempt to stop the destruction, the government began importing sparrows from the Soviet Union. Following this disaster, Mao quickly protected tree sparrows and added bedbugs to his lest of four pests instead. This example illustrates the severe damage that can be inflicted when sweeping changes are made to an ecosystem.

Shen Nan (沈枬)
1959, February
Eliminating the last sparrow
This poster was meant for use in schools, and was part of a series. Sparrows were one of the Four Pests, together with flies, mosquitoes, and rats.


What can we learn from these failures in providing effective management of pest species? In both the European and Chinese stories, the problem came from a basic misunderstanding of how sparrows function in an ecosystem. Prior to the European sparrow population explosion of the 1700’s, written accounts show that some were already advocating for control of sparrows by destroying nests and eggs. But it wasn’t until the population exploded and started decimating crops that any action was taken. In China’s case, the government thought that tree sparrows strictly fed on seeds, and it wasn’t until after the sparrow population had been destroyed that they found research showing that tree sparrows also can control insect populations because they do feed on insects during breeding season.

The sparrows in China and Europe were a native species, but house sparrows were purposely introduced from Great Britain to the United States in the 1850’s as a form of pest control. 50 years after their introduction, house sparrows had spread virtually across the entire country and are almost universally regarded as pests. Instead of providing pest control, house sparrows are competing with our native bluebirds, and this all stemmed from a lack of understanding of the species.
These stories highlight the importance of incorporating good science into management strategies for wildlife. With your help on the Sparrow Swap Project, we will be able to improve our understanding of how different management strategies impact house sparrows and native birds, which will hopefully ultimately lead to better management decisions in the future. By participating, you are providing data and increasing knowledge that will be instrumental in providing effective management for our native songbirds.


If you would like to learn more about the “4 pests campaign in China, check out this article!
If you are interested in reading more about the story of sparrows in general, check out tthis article written by NC State Professor Rob Dunn!

This post was written by Dominic Eannarino, a recent graduate from NC State. You can learn more about Dominic and the rest of the Sparrow Swap Team on our team page.

Sparrow Swap Q & A

On June 13th,2018 we held our first live Q & A about Sparrow Swap! Hopefully there will be more in the future!
You can watch the video here!

2017 Summary Results Handout!

Hello Everyone We’ve created a shareable PDF summarizing our results so far.

Click to download!

Finding the spots!

It’s Suzanne here, and I’ve got some exciting news to share! Last summer a lab out of the University of Seville, Spain released a program called SpotEgg that uses computer vision to find the spots on an egg.

This is a breakthrough for egg color and pattern research. In previous studies spots on eggs were scored by human eyes into broad groups. For example, an egg with no spots might be given a score of 1 while and egg covered in spots given a score of 5. Now, with the help of SpotEgg we are able to quantify exactly how many spots there are, how much area those spots cover, the color of those spots, and color of the background of the egg.

Over the last few months, the Sparrow Swap Team, with the help of one of the SpotEgg creators have been working out the kinks to be able to use SpotEgg to study the color and pattern of our house sparrow eggs. This is the first step to determine whether house sparrow eggs can be used as indicators of contaminants in the environment.

Today, We are excited to share with you some of the first photos from the eggs!

In order to use SpotEgg, we first have to take photos of every clutch using the same camera settings. This includes, a grayscale color card to make sure we can adjust the color, and a scale to be able to determine the size of the spots.

Here is what the photos look like before we run them through the program.

After we inspect the photos to make sure the are of the highest quality, we are ready to use SpotEgg to find the spots. While the computer does most of the work, it is still a tedious process to make sure every photo is correctly photographed, set up in the program, and that the computer accurately found the spots.
There are some few minor details to work out but here is one of our first photos where SpotEgg found the spots.

In addition, the program also creates a black and white version showing where the spots are.

Now let’s Take a closer look at Egg D.
The program has found the edges of the spot by comparing pixels side by side. If there is is a large difference between the two pixels, the computer defines that as an edge. By comparing all the pixels, the program is able to find the spots.

Just to give a you a little taste of the information we can get from SpotEgg, here are some numbers for Egg D.

Spots: 266

Area covered by spots: 44%

Length: 19.7 mm

Width: 16.6 mm

Volume: 698mm3

We are excited to be working on analyzing the photos from the 400 clutches we have in the Sparrow Swap collection over the next few months!

Once the photos are process through SpotEgg, we will be able to begin to look for patterns across the country in therms of color and spots!

Unsure of how to participate in Sparrow Swap?

There are many ways to participate in Sparrow Swap from a one time egg collection to more extensive nestbox monitoring. To help you decide which way is best for you, we’ve created this flow chart.

We hope this helps you find the way to participate that works best for you!


The Sparrow Swap Team

2017 Preliminary Results!


Wondering why we use SciStarter?

Many of you might be wondering why we use SciStarter to manage our project.

SciStarter is a  website where citizen scientists can find, join, and contribute to science through more than 1600 formal and informal research projects and events.  

If you are already participating in other projects like, nestwatch, ebird, inaturalist, or project feederwatch, SciStarter is a way for you to keep track of your contributions to those projects as well as Sparrow Swap.

I’d like to introduce you to some of SciStarter’s features:

Messaging – We are happy to announce that you can now respond to the messages you receive from Sparrow Swap using your email. You can still log-in to SciStarter to see your sent and received SciStarter messages (see photo below). Please note, we cannot receive photos this way. If you need to send us a photo, email us at sparrowswap@ncsu.edu.

Your Profile- Through your profile (see below) you can fill out at a little more about your interests, activities, skills, and instruments.  Once you do this, SciStarter will recommend other projects you may be interested in. Your profile also gives you an overview of the number of projects you are participating in and your total number of contribution to SciStarter Affiliated projects, like Sparrow Swap. Right now, if you complete 3 tasks to complete your profile, you can receive a free ebook “The Rightful Place of Science: Citizen Science!” that features a chapter written by Dr. Caren Cooper, Sparrow Swap’s lead researcher.

Your Dashboard: The dashboard is a place for you to view and manage projects you are participating in. (See Below). 

My Projects, Bookmarks & Events – If you click on the My projects, Bookmarks & Events, you can get a more detailed look into the projects you are participating in. If you have joined a project, and haven’t participated in a while, the “Jump In” will direct you to resources you need to contribute!

We know SciStarter has been changing throughout this season and we appreciate everyone’s patience and feedback as we all have been adjusting to the changes!

If you have any questions or comments, don’t hesitate to ask!


Sparrow Swap Team

What happens to the eggs?


Happy Summer!

We have been busy in the lab processing over 50 clutches that have arrived at the Museum! 

Once at the Museum, we use every part of the egg to determine differences in color and speckling, eggshell thickness, water loss through the eggshell, embryo development, persistent contaminants in the eggs, and the diet of the mother.

First, each clutch is assigned a catalog number, a unique number that separates the clutch from all other specimens in the Museum’s collections. Each individual egg in a clutch is then assigned a letter. Our intern, Imani, carefully removes the eggs from the plastic Easter egg packaging and inspects them for any cracks that may have occurred during packaging and shipping.

After unpacking, Aubrey meticulously photographs each clutch using a standard technique to be able to compare color and size of each egg to each other. Later the photographs are analyzed by our collaborator Dr. Daniel Hanley, to compare the variation in eggshell color and speckling between clutches across the United States.

Next we use a dremel to carefully cut around the base of the eggshell, being care not to cut through the membrane. The cut piece of eggshell is lifted off the egg and the contents of the egg are placed in a certified contaminant free jar. Once in the jar, we can determine the development stage of the embryo. These jars will later be sent off to be analyzed for persistent environmental contaminants such as PCBs, DDT, and heavy metals.


Currently, we are working on acquiring the tools and protocols to be able to measure the individual thickness of each eggshell, the water loss the happens across the eggshell, and the collecting eggshell membranes from each clutch to gain some clues into the diets of the mother. By gathering all of this data on each egg, we hope to find clues to understanding the natural variation in eggshells and the variation that may be caused by contaminants! 

Finding Adventure in Studying House Sparrows

Suzanne spent some time the last two weeks in Lexington, Kentucky visiting researchers, including Dr. Dave Westneat, who are doing work involving house sparrows at the University of Kentucky. Dave Westneat has been studying house sparrows for over 25 years. Dave has written in that past that:

“choosing to study House Sparrows would seem to ensure one a dull life. No adventures or extraordinary bravery in the face of extreme conditions are necessary. With some common birds, such as Red-winged Blackbirds, one can at least imagine being a stoic adventurer who slogs through impenetrable marsh in pursuit of (somewhat) elusive quarry. There simply is no romance in studying sparrows. Yet House Sparrows offer another kind of adventure—of a more intellectual nature. And as one comes to know these birds intimately, they emerge as creatures both charming and mysterious.”

Because they are so common and not protected by the Migratory Bird Treaty Act, house sparrows have served as a perfect study organism for researchers, including Westneat and the Sparrow Swap Team, to study many different aspects of general bird biology.

Currently most of the research Dave and his team are conducting involves studying the behavior of house sparrows. During a year where they had a high population of house sparrows, Dave’s team noticed that entire broods were dying within the first 72 hours of hatching. They think that with so many pairs looking for suitable nesting sites, there is more prospecting of birds into nestboxes already inhabited. The pair of house sparrows currently using the nestbox may then spend more time defending their nest than providing food for the hatchlings! Since observing this phenomena, they have just started conducting aggression tests to see how house sparrow pairs respond to a stuffed house sparrow “intruder” that is placed on the side of the nestbox during the first few days after hatching. The Sparrow Swap Team is looking forward to following up with them in the future to see what they discover!

Egg Packaging Instructions

Unsure how to mail the house sparrow eggs to us at the Museum?

Watch the video below to find how you can use items found around the house to package the eggs.