U.S. iPhone app downloads fall after big holiday season

It looks like the brand-new shininess of millions of new iPhones(s aapl) has lost a little luster since the holidays. After months of steadily increasing activity in the iTunes App Store, post-iPhone 4S launch, the number of daily app downloads in the U.S. took a big nosedive in March, falling 30 percent from February, according to mobile app marketing firm Fiksu.

Fiksu tracks the daily U.S. traffic of the top 200 free apps in the App Store, and found that starting with the iPhone 4S smartphone’s launch last fall, download activity ramped up from 3.8 million daily downloads in September to peak at 6.79 million downloads in January, driven by the holiday boom in iPhone sales. Downloads fell slightly in February to 6.35 million and then plummeted by nearly 2 million to 4.45 million total downloads in March.

“With the novelty factor of the iPhone 4S launch and the holidays well behind us, and no other events in March to spark discovery, March’s download dip was expected,” Fiksu CEO Micah Adler said in a statement. “An unexpected contributing factor could be the decline in the use of robotic install tactics by app marketers responding to Apple’s new policy.”

It’s also worth noting that Fisku only tracks U.S. numbers, so international downloads could still be high. While Verizon Wireless (s vz)(s vod) and AT&T(s t) saw their iPhone sales dip in the first quarter, Apple more than made up for it with strong international smartphone sales.

Though U.S. iPhone owners may be downloading fewer apps, that doesn’t mean they’re using their phones less. Fiksu also tracks a metric it calls the Cost per Loyal User Index, which measures the marketing costs developers spend to secure a loyal customer – one who opens their apps at least three times a month. In December, that cost reached $1.81 per user, but it dipped down to $1.14 in January and held steady at about $1.30 in the previous two months. So while iPhone customers may not be downloading as many new apps today, they look to be spending more time with the apps they already have.