There is simply no reliable substitute for exhaustive due diligence when paring down a list of potential investments, but fielding ideas from the right sorts of sources can help to reduce risk from the start.

For investors looking to gold and silver miners for exposure to the bullish long-term outlook for prices of those metals, it's hard to ignore Sprott Asset Management as a compelling source of investment ideas within the sector. During the first quarter of 2011, SEC filings show the precious-metal specialist making a number of interesting moves.

An understandable round of profit-taking led to slightly reduced stakes in several of Sprott's noteworthy outperformers, including a 19% reduction in its holding of silver streaming sensation Silver Wheaton (NYSE: SLW) that dropped the equity to fourth position within Sprott's portfolio. Perhaps more interesting from a strategic standpoint, meanwhile, are the two stocks that moved above Silver Wheaton on the list as a result of the minor shuffle. After a pair of portfolio-dominating positions in his own Sprott Physical Silver Trust (NYSE: PSLV) and the Sprott Physical Gold Trust -- with a combined market value of more than $250 million -- Sprott's next-largest holdings were First Majestic Silver (NYSE: AG) and Alexco Resource (AMEX: AXU), respectively. First Majestic certainly has the Midas touch, and Alexco's bonanza-grade discoveries at Keno Hill portend a meaningful success story in the works for the recently crowned producer. Sprott also pared its stake in Claude Resources by about 7%, but the small-scale producer with the large-scale discovery at Amisk remains a top-ten holding.

Subsequent to the quarter-end, it is worth noting, Sprott reportedly liquidated some $34 million worth of the Sprott Physical Silver Trust, and Fools will no doubt join me in anticipating the second-quarter filing to see which silver equities were purchased with the proceeds of those sales.

Among the stand-out purchases executed during the first quarter, Sprott doubled-down during the period on its stake in the company that Fortune Magazine heralded as the fastest-growing company for 2010: Eldorado Gold. Eldorado is a prime choice for investors looking for exposure to gold production in China, and continues to offer the most aggressive production growth profile among its peers. Sprott also added 36% to its stake in Yamana Gold (NYSE: AUY), which this Fool has repeatedly touted as one of the most undervalued stocks in its class. Since I first included the stock among my top 10 picks in the sector for 2011, my assessment of Brigus Gold's (AMEX: BRD) upside potential has only grown stronger, and so I enjoy observing that Sprott Asset Management increased its stake in Brigus during the first quarter.

Finally, I would like to point out a new $25.7 million investment by Sprott in Extorre Gold Mines (AMEX: XG), which only recently secured a listing on the AMEX exchange. Observing the stock's speedy five-bagger explosion since its spinout from Exeter Resource last year, and the fact that its market capitalization is now more than twice that of Exeter, I think all of Fooldom will appreciate this terrific call made by former Fool contributor Toby Shute. Toby's astute analysis serves as a timely reminder that the biggest things in mining can often come in smaller packages.

Fool contributor Christopher Barker can be found blogging actively and acting Foolishly within the CAPS community under the username TMFSinchiruna. He tweets. He owns shares of Alexco Resource, Brigus Gold, Claude Resources, Eldorado Gold, Exeter Resource, First Majestic Silver, Silver Wheaton, and Yamana Gold. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a golden disclosure policy.