MEASURING POLLINATION: A LOOK AT BEE FLIGHT HOURS
Updated: Dec 22, 2022
Earlier this year, I wrote about the impact of weather during almond pollination, comparing data from 2019 and 2020. For this analysis, I used a metric known as Bee Flight Hours to compare optimal weather conditions for bee activity. Bee Flight Hours is a rudimentary formula that roughly estimates how much time the bees have to pollinate given the weather conditions.
Flaws with Bee Flight Hours
Here’s the most common formula: Bee Flight Hours = number of daylight hours in which weather is over 55 degrees, below 10MPH wind and no precipitation.
Bee Flight Hours has its limitations. One could even point to the results from my January post to argue that Bee Flight Hours is a deeply flawed metric. After all, how could historically bad pollination season weather in 2019 result in a record almond yield, beating the previous record by more than 10%? Either the bees are getting the job done outside of Bee Flight Hours or their work isn’t as directly linked to yield as we think. It’s safe to toss out the latter explanation—I have confidence in the experts with decades of pollination research under their belts.
So, are the bees pollinating outside of Bee Flight Hours? Almost certainly. If you’ve been around a beehive below 55 degrees, above 10MPH wind or in light rain, you know that bees still fly in these conditions. Sure, the weather isn’t “optimal” for bee flight, but they will fly and they will visit flowers and transfer pollen.
Take Bee Flight Hours for what it is—a rough way to estimate if bees should be flying. But a bee flight hour doesn’t necessarily mean bees are delivering maximum pollination. To gain any value from Bee Flight Hours, you still need strong bees.
From a grower’s perspective, one Bee Flight Hour isn’t very informative unless you know the strength of your hives. A stronger hive dispatches a larger percent of the total colony population to forage and transfer pollen between flowers. Here’s a rough breakdown of the pollination value delivered by a hive based on colony size:
Clearly, one Bee Flight Hour doesn’t have the same meaning to every grower. A grower with a 12-frame average should expect strong pollination activity in that hour. But a grower with a 4-frame average? Well, let’s just say they’re getting what they paid for.
Bee Flight Hours is missing important context. Knowing that bees should be flying when it’s warm and sunny isn’t helpful. Growers need to know the bottom line—how are my outcomes impacted? Do I have enough bees to complete the job? Do I need to take action?
To help our growers answer these questions, we’re building a new model that incorporates hive strength into Bee Flight Hours, called Pollination Score. Measured on a scale of 1 to 5 (5 being the best possible score), Pollination Score is designed to indicate whether your bees are strong enough to deliver maximum pollination given the weather conditions.
Once your hive strength results are loaded to your Verifli dashboard, your custom Pollination Score will appear on the Summary page. Pairing your Verifli results with local weather data from each of your orchards, you’ll get a measurement of bee activity that’s completely unique to you.
Measuring pollination is an under-researched aspect of the crop production cycle. Though Bee Flight Hours isn’t something growers monitor, an updated model tied to hive strength has promise to become a valuable indicator growers can actually use to drive pollination decisions. Improving Bee Flight Hours won’t revolutionize pollination, but it might lead to a more comprehensive understanding of how weather impacts pollination.