UPDATE

The suggested use of JSON::XS#INCREMENTAL-PARSING looks like the much better solution for such kind of parsing problems. graff++

> If there is a good separator like blank line(s), you can set the input record separator $/ accordingly.

You didn't show us more than one object and your link is broken. So I had to guess they all start with '{"created_at":' at line's start.

And I shortened your objects for better demonstration

use v5.12.0;
use warnings;
use Data::Dump;
use JSON::XS;

my $ident ='{"created_at":';
local $/ = "\n$ident";


my $prefix="";


while (<DATA>) {
    chomp;                              # removes $/ from the end
    my $obj = "$prefix$_";
    ddx $obj;
    say "-" x 30;
    dd decode_json($obj);
    #say "-" x 72;
    $prefix = $ident;
}



__DATA__
{"created_at":"Sat Mar 02 18:45:26 +0000 2013","id":307924626426695681
+,"id_str":"307924626426695681","etc":"***YADDA YADDA ***","id_str":"2
+621098741943851970"}
{"created_at":"Sat Mar 02 18:45:26 +0000 2013","id":307924626426695681
+,"id_str":"307924626426695681","etc":"***YADDA YADDA ***","id_str":"2
+621098741943851970"}
{"created_at":"Sat Mar 02 18:45:26 +0000 2013","id":307924626426695681
+,"id_str":"307924626426695681","etc":"***YADDA YADDA ***","id_str":"2
+621098741943851970"}
[download]

# raw_json.pl:16: "{\"created_at\":\"Sat Mar 02 18:45:26 +0000 2013\",
+\"id\":307924626426695681,\"id_str\":\"307924626426695681\",\"etc\":\
+"***YADDA YADDA ***\",\"id_str\":\"2621098741943851970\"}"
------------------------------
{
  created_at => "Sat Mar 02 18:45:26 +0000 2013",
  etc => "***YADDA YADDA ***",
  id => 307924626426695681,
  id_str => 2621098741943851970,
}
# raw_json.pl:16: "{\"created_at\":\"Sat Mar 02 18:45:26 +0000 2013\",
+\"id\":307924626426695681,\"id_str\":\"307924626426695681\",\"etc\":\
+"***YADDA YADDA ***\",\"id_str\":\"2621098741943851970\"}"
------------------------------
{
  created_at => "Sat Mar 02 18:45:26 +0000 2013",
  etc => "***YADDA YADDA ***",
  id => 307924626426695681,
  id_str => 2621098741943851970,
}
# raw_json.pl:16: "{\"created_at\":\"Sat Mar 02 18:45:26 +0000 2013\",
+\"id\":307924626426695681,\"id_str\":\"307924626426695681\",\"etc\":\
+"***YADDA YADDA ***\",\"id_str\":\"2621098741943851970\"}\n"
------------------------------
{
  created_at => "Sat Mar 02 18:45:26 +0000 2013",
  etc => "***YADDA YADDA ***",
  id => 307924626426695681,
  id_str => 2621098741943851970,
}
[download]