Click to enlarge. Source: CIRP

FORTUNE — Here’s more evidence that Google’s GOOG Android is peaking and (as if we needed it) that Research in Motion’s RIMM BlackBerry is headed south. In a survey released to clients Thursday, the Consumer Intelligence Research Partners found that more iPhones were purchased in April by U.S. customers leaving Apple’s AAPL competitors than by owners of earlier iPhone models. Of the customers who bought iPhones in April, according to CIRP:

  • 42% were switching from another smartphone, up from 36% in February.
  • Specifically, 38% were coming from either Android or BlackBerry, up from 29%.
  • 34% were upgrades from earlier iPhones, down from 71% immediately after the iPhone 4S launch last fall
  • 24% were switching from a feature phone or buying their very first mobile phone.

The survey also found that the iPad 2 continued to sell well after the March launch of the new iPad. The discounted iPad 2 accounted for 41% of U.S. sales in April compared with 59% for new iPad. The 3G/4G versions of both iPad models sold better than the WiFi‐only versions, accounting for 55% of total sales.