Birders View of the Seasons
Winter: December - February
Winters in the Rio Grande Valley are generally mild with temperatures ranging in the 40s to 50s up to the 60s to 80s. Freezes in the RGV are rare. It’s this time of year that the temperate birds invade from the cold north. Often times, the cold fronts bring birds down with them.
Geese are regularly heard flying overhead and a wide variety of ducks are seen as well as cranes out in agriculture fields. The RGV is host to many wintering passerines, both transients and winter residents. Some of the more common winter birds include the Ruby-crowned Kinglet, Blue-gray gnatcatcher and Orange-crowned Warbler. These birds often form mixed flocks, in which you’ll regularly see Valley residents such as Black-crested Titmouse interspersed. There are many other warbler and vireo species that can be seen as well.
Winter is also the time of year when many of our rarities are spotted, given how many visiting eyes are on nature. The Blue Bunting, Crimson-collared Grosbeak and Masked Duck are just a few examples of the many different rarities possible. By February the transition to spring is beginning; trees beginning to grow leaves and early breeding birds such as Long-billed Thrashers and Black-crested Titmouse are singing.
Spring: March - May
The peak migration is between April and May and “norther” cold fronts can cause massive fallouts on South Padre Island and especially along the cost but inland as well.
The wintering birds begin to filter out in early spring and are nearly all gone by the beginning of summer. The transients (neotropical or long-distance migrants) pass through during this time as well. Meanwhile, the permanent resident species such as the Great Kiskadee, Plain Chachalaca, Altamira Oriole and Green Jay begin breeding.
Summer: June - September
This is the Rio Grande Valley’s longest season of the year and temperatures are sizzling! The heat index is nearly always in the upper 90s to 100s with the humidity ranging from 30 to 50 percent.
By early summer many of our permanent residents are on their second brood, while the summer residents like the Groove-Bill Ani and Western Kingbirds are on their first and usually only brood. There is little to no migration in the early summer months (June through July) for the most part, though there are the occasional late migrants trickling through. Some molting can begin, but many birds delay to try and squeeze in one more brood.
In late summer (August through September) fall migration begins for many species, such as the Orchard Oriole and various Empidonax species, but it’s very subtle because of the very dense foliage, which makes it difficult to see the birds passing through.
This time of year is the permanent resident’s main molting period after breeding and they grow very inconspicuously. A few species continue breeding, such as the Mourning Dove and Northern Beardless Tyrannulet.
Fall: October - November
The Rio Grande Valley’s “true” fall is very short and unlike many of the northern areas the leaves on the trees don’t produce the spectacular autumn colors. The weather is highly variable with a few cool fronts periodically passing through the area.
The purely summer residents leave, except for the few Groove-Bill Anis and Olive Sparrows that stay over through the winter. At this time winter residents like the Orange-crowned Warbler, Ruby-crowned Kinglet and Blue-Gray Gnatcatcher arrive. This is the time of year when Scissor Tailed Flycatchers (summer residents) are seen in migratory flocks over fields.