0 the common yellowthroat (geothlypis trichas) is a new world warbler .
1  they are abundant breeders in north america , ranging from southern canada to central mexico .
2 common yellowthroats are small songbirds that have olive backs , wings and tails , yellow throats and chests , and white bellies .
3  adult males have black face masks which stretch from the sides of the neck across the eyes and forehead , which are bordered above with white or gray .
4  females are similar in appearance , but have paler underparts and lack the black mask .
5  immature birds are similar in appearance to the adult female .
6  first-year males have a faint black mask which darkens completely by spring .
7 there are 13 races of this bird .
8  these races differ mainly in the males' facial patterns and the brightness of the yellow underparts .
9  the southwestern forms of this bird are the brightest and the yellowest below .
10 the breeding habitats of these birds are marshes and other wet areas with dense low vegetation , and may also be found in other areas with dense shrub .
11  however , these birds are less common in dry areas .
12  females appear to prefer males with larger masks .
13  common yellowthroats nest in low areas of the vegetation , laying 35 eggs in a cup-shaped nest .
14  both parents feed the young .
15 northern races are nocturnal migrants , wintering in the southern parts of the breeding range , central america and the west indies .
16  southern forms are largely resident .
17  this species is a very rare vagrant to western europe .
18 these birds feed on insects , which are usually captured in dense vegetation , but sometimes caught in midair .
19 the common yellowthroat's song is a loud twichety twichety twichety twich .
20  its call is a soft jip .
21 despite a decline in numbers in some areas , which is due to loss of favoured habitat , this species is still very common .
22 routes of migration vary based on the season and location of common yellowthroats .
23  during fall migration , from august to october , common yellowthroats in canada , western , eastern , and central u .
24 s .
25 , and regions outside of the united states all have unique migration routes .
26  when migrating in the fall months , all adults and immature individuals tend to arrive at their migration destinations around the same time .
27  migration differences in timing and routes are also seen during the spring months from early february to late may in these same groups across the united states , canada , and other areas .
28  however , males generally arrive at their destination site before the females during the spring migration months .
29  during both fall and spring migration , many birds take time to rest during a stopover period .
30  some individuals stay at their stopover destinations for several weeks or months while others spend only a few days resting before they continue on in their migration patterns to their final destination .
31 one place of study on common yellowthroat migration that is unique and worth noting is appledore island , maine .
32  common yellowthroats here typically migrate to this island during the spring months displaying distinct patterns of movement and stopover ecology .
33  analysis of the common yellowthroat spring migration from april to june was observed by researchers from the department of biology at canisius college in buffalo , new york to determine patterns of migration and time spent resting on the island before continuing on their journey .
34  birds returning for more than the second time arrive earlier than birds migrating to the island for their first time .
35  every year , males tend to arrive on the island an average of five days earlier than females weighing more than the females upon arrival .
36  one possible explanation for the early arrival of males to this island is the ability of males to set up territories before the females arrive .
37  this could give them better access to resources and a higher likelihood of finding a female mate .
38  however , both sexes spend about a week on the island before leaving .
39 migration of common yellowthroats in florida has also been extensively studied .
40  in florida , the common yellowthroat can be found more often in the southern peninsular region rather than the northern panhandle region closer to the mainland of the united states .
41  peak migration times of the birds in this region are during the last week of september through the second week of october .
42  not as much is known about spring migration in florida , but the patterns appear similar to that of the autumn migration .
43 future studies are needed to understand specific migration patterns of common yellowthroats in other parts of the united states .
