In the fiercely competitive mobile market, Android has surpassed Apple iOS as the market leader in mobile application downloads in the second quarter of 2011, according to a new industry report.

Market shares of Android and iOS were 44 percent and 31 percent, respectively, according to figures released today by ABI Research.

Lim Shiyang, research associate attributed Android’s open source strategy as the main factor for its success.

“Being a free platform has expanded the Android device install base, which in turn has driven growth in the number of third party multi-platform and mobile operator app stores,” Shiyang said in a statement. “These conditions alone explain why Android is the new leader in the mobile application market.”

ABI also said that recent quarterly shipment growth figures also explain Android’s leap to the top app download position. 

iPhone shipment growth in Q2 2011 slowed to nine percent from 15 percent a quarter earlier. In contrast, Android smartphone shipments increased 36 percent in Q2 2011, compared to 20 percent in Q1. Android’s install base now exceeds iOS by a factor of 2.4-to-1 worldwide; by 2016 this factor will grow to 3-to-1, ABI said.

However, despite leading in total mobile application downloads, Android’s app downloads per user still lag behind Apple’s by 2-to-1, according to Dan Shey, practice director, mobile services at ABI.

“Apple’s superior monetization policies attracted good developers within its ranks, thus creating a better catalog of apps and customer experience,” Shey said.

According to ABI, global app downloads for year-end 2011 are expected to swell to 29 billion, compared to only nine billion in 2010. Such increases are largely due to the proliferation of smartphones around the world, ABI added. The total smartphone install base is expected to grow 46 percent in 2011.

In a report released in September 2011, mobile app downloads are expected to increase 144 percent during 2011 compared to last year, according to a research firm study. Ovum also predicted that app downloads for Android devices would exceed those for Apple iOS devices for the first time, TechZone360 reported.

“Consumers’ seemingly insatiable demand for mobile applications is set to continue this year, with downloads from app stores increasing around the world,” Ovum analyst Nick Dillon said in a statement reported by Digital Trends. “The outlook for the longer term is also positive, with consumers set to continue to use apps to add new features to their phones and to access their favorite services on the go.”

Ovum predicted Android will see about 8.1 billion app downloads in 2011, compared to about 6 billion for Apple’s iOS devices.

In 2010, Apple saw 2.7 billion app downloads and Android saw 1.4 billion app downloads, according to Digital Trends.