Birder's require many tools for their trade; quick reflexes, good memories, discerning vision, and, of course, truckloads of favorable fortune! But at those times when fortune doesn't smile, it certainly helps to have a trick or two up your sleeve.
Since small passerines (i.e. perching birds) have a propensity for taking cover in thickets that even the most powerful optics can't see through, it helps to have inticements to bring them out into the open. Since most of us don't carry fully stocked bird feeders with us into the field (not that that would even assure their use by the desired birds), let me suggest two vocal assaults to add to your arsenal:
No one has the answer to why it works, but in many cases, simply making a "pishing" sound will draw birds out of their cover. Some suggest that it imitates an alarm call and birds will come to assist the comrade being attacked. Others suggest that the sound is similar to that made by young birds begging for food. In any case, pishing can be effective at any time of year, and the results vary by species. Gray Catbirds seem to be curious by nature (curiosity killed the catbird?) and invariably respond by popping up into full view if they are in the vicinity. Pishing also tends to be effective with sparrows and "dickie" birds (chickadees, titmice, nuthatches, etc.) Results seem to vary with warblers, but then any birder will tell you just how fickle these migrants can be! Pishing is a simple skill anyone should be able to easily master. No special instructions are necessary, simply make a noise that sounds something like this.
SCREECH OWL CALL
This involves a lot of embarassing practice which is best done in private and utilizes that little thingie in the back of your throat -- the uvula (if you're old enough to remember, I'm sure you'll recall that funny Saturday Night Live sketch with the classic line, "I must have stupidly glossed right over my uvula") If you can roll your R's, then you are halfway there. This involves using saliva on the back of your tongue to make the uvula vibrate. All I can say is "practice, it will come." Now comes the tricky part, whistle while you do this and make it sound something like this. Imitating a screech-owl is obviously good for attracting screech-owls, but it is also effective in attracting other species. Eastern Screech-owls are actually quite common, especially in wooded areas, but even in suburbia. They also are rather responsive given the right conditions (wind over 15 mph is a killer, and rain is not much better). Of course this needs to be done at night although it is not impossible to find owls in the daylight with this method. In the daylight however, imitating a screech-owl works much like pishing, but usually with better results. It has been my experience that this is more effective than pishing when warblers.
A WORD ON ETHICS
An ethical birder would, of course, never harass the object of his or her passion, i.e. the birds themselves. Still, it is far too easy to be overcome with obsession and overdo pishing or screech-owl calling. During the nesting season, they should not be used at all, as eggs are vulnerable to the elements and predators and thus should not be left unduly unattended. Even at other times, birds should not be whipped up into a frenzy by an overzealous birder. It is my aim in assisting you with these tools to enhance your birding and ultimately serve the birds themselves by bringing positive attention to them and the habitat they inhabit, perhaps helping to preserve both. So please use these tools wisely and.....enjoy!